diff --git a/fuzzers/007-timing/Makefile b/fuzzers/007-timing/Makefile
index 5734d78a..20da5da5 100644
--- a/fuzzers/007-timing/Makefile
+++ b/fuzzers/007-timing/Makefile
@@ -1,7 +1,7 @@
 # for now hammering on just picorv32
 # consider instead aggregating multiple projects
-PRJ?=picorv32
-PRJN?=8
+PRJ?=oneblinkw
+PRJN?=1
 
 all: build/timgrid-v.json
 
diff --git a/fuzzers/007-timing/checksub.py b/fuzzers/007-timing/checksub.py
index 86823805..34ab981a 100644
--- a/fuzzers/007-timing/checksub.py
+++ b/fuzzers/007-timing/checksub.py
@@ -60,7 +60,7 @@ def pds(Ads, s):
 def run(fns_in, sub_json=None, verbose=False):
     assert len(fns_in) > 0
     # arbitrary corner...data is thrown away
-    Ads, b = loadc_Ads_b(fns_in, "slow_max", ico=True)
+    Ads, b = loadc_Ads_b(fns_in, "slow_max")
 
     if sub_json:
         print('Subbing JSON %u rows' % len(Ads))
@@ -111,14 +111,14 @@ def main():
 
     parser.add_argument('--verbose', action='store_true', help='')
     parser.add_argument('--sub-json', help='')
-    parser.add_argument('fns_in', nargs='*', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='*', help='timing4i.csv input files')
     args = parser.parse_args()
     # Store options in dict to ease passing through functions
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     sub_json = None
     if args.sub_json:
diff --git a/fuzzers/007-timing/corner_csv.py b/fuzzers/007-timing/corner_csv.py
index a4ccbf84..8b7290a3 100644
--- a/fuzzers/007-timing/corner_csv.py
+++ b/fuzzers/007-timing/corner_csv.py
@@ -28,10 +28,12 @@ def main():
 
     parser.add_argument('--verbose', type=int, help='')
     parser.add_argument(
-        '--auto-name', action='store_true', help='timing3.csv => timing3c.csv')
+        '--auto-name',
+        action='store_true',
+        help='timing4i.csv => timing4c.csv')
     parser.add_argument('--out', default=None, help='Output csv')
     parser.add_argument('--corner', help='Output csv')
-    parser.add_argument('fns_in', nargs='+', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='+', help='timing4i.csv input files')
     args = parser.parse_args()
     bench = Benchmark()
 
@@ -40,8 +42,8 @@ def main():
         if args.auto_name:
             assert len(args.fns_in) == 1
             fnin = args.fns_in[0]
-            fnout = fnin.replace('timing3.csv', 'timing3c.csv')
-            assert fnout != fnin, 'Expect timing3.csv in'
+            fnout = fnin.replace('timing4i.csv', 'timing4c.csv')
+            assert fnout != fnin, 'Expect timing4i.csv in'
         else:
             fnout = '/dev/stdout'
     print("Writing to %s" % fnout)
@@ -49,7 +51,7 @@ def main():
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     run(fout=fout, fns_in=fns_in, corner=args.corner, verbose=args.verbose)
 
diff --git a/fuzzers/007-timing/csv_flat2group.py b/fuzzers/007-timing/csv_flat2group.py
index a0f76f1d..d382e6f1 100644
--- a/fuzzers/007-timing/csv_flat2group.py
+++ b/fuzzers/007-timing/csv_flat2group.py
@@ -5,7 +5,7 @@ from timfuz import Benchmark, loadc_Ads_bs, index_names, load_sub, run_sub_json,
 
 def gen_group(fnin, sub_json, strict=False, verbose=False):
     print('Loading data')
-    Ads, bs = loadc_Ads_bs([fnin], ico=True)
+    Ads, bs = loadc_Ads_bs([fnin])
 
     print('Sub: %u rows' % len(Ads))
     iold = instances(Ads)
@@ -45,14 +45,14 @@ def main():
         required=True,
         help='Group substitutions to make fully ranked')
     parser.add_argument('--out', help='Output sub.json substitution result')
-    parser.add_argument('fns_in', nargs='+', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='+', help='timing4i.csv input files')
     args = parser.parse_args()
     # Store options in dict to ease passing through functions
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     sub_json = load_sub(args.sub_json)
 
diff --git a/fuzzers/007-timing/csv_group2flat.py b/fuzzers/007-timing/csv_group2flat.py
index c6adf0c6..6f1e31b1 100644
--- a/fuzzers/007-timing/csv_group2flat.py
+++ b/fuzzers/007-timing/csv_group2flat.py
@@ -4,7 +4,7 @@ from timfuz import Benchmark, loadc_Ads_bs, load_sub, Ads2bounds, corners2csv, c
 
 
 def gen_flat(fns_in, sub_json, corner=None):
-    Ads, bs = loadc_Ads_bs(fns_in, ico=True)
+    Ads, bs = loadc_Ads_bs(fns_in)
     bounds = Ads2bounds(Ads, bs)
     # Elements with zero delay assigned due to sub group
     group_zeros = set()
diff --git a/fuzzers/007-timing/minitest/test_cell_opins.tcl b/fuzzers/007-timing/minitest/test_cell_opins.tcl
new file mode 100644
index 00000000..a62fb407
--- /dev/null
+++ b/fuzzers/007-timing/minitest/test_cell_opins.tcl
@@ -0,0 +1,30 @@
+# Demonstrates that cells can have 0 to 2 BEL output pins
+# roi/dout_shr_reg[0]: roi/dout_shr[0]_i_1/O roi/dout_shr_reg[0]
+
+set TIME_start [clock clicks -milliseconds]
+set site_src_nets 0
+set neti 0
+set nets [get_nets -hierarchical]
+set nnets [llength $nets]
+set opins_zero 0
+set opins_multi 0
+foreach net $nets {
+    incr neti
+    puts "Net $neti / $nnets: $net"
+
+    set out_pins [get_pins -filter {DIRECTION == OUT} -of_objects $net]
+    set npins [llength $out_pins]
+    if {$npins == 0} {
+        puts "    $net zero source pins: $src_pin"
+        incr opins_zero
+    }
+    if {$npins > 1} {
+        puts "    $net multi source pins: $src_pin"
+        incr opins_multi
+    }
+}
+set TIME_taken [expr [clock clicks -milliseconds] - $TIME_start]
+puts "Took ms: $TIME_taken"
+puts "Result: $opins_zero / $nnets zero"
+puts "Result: $opins_multi / $nnets multi"
+
diff --git a/fuzzers/007-timing/minitest/test_linprog.py b/fuzzers/007-timing/minitest/test_linprog.py
new file mode 100644
index 00000000..78c8c24a
--- /dev/null
+++ b/fuzzers/007-timing/minitest/test_linprog.py
@@ -0,0 +1,139 @@
+#!/usr/bin/env python3
+
+import scipy.optimize as optimize
+import numpy as np
+import glob
+import json
+import math
+import sys
+import os
+import time
+
+
+def run_max(Anp, b, verbose=False):
+    cols = len(Anp[0])
+
+    b_ub = -1.0 * b
+    A_ub = [-1.0 * x for x in Anp]
+
+    res = optimize.linprog(
+        c=[1 for _i in range(cols)],
+        A_ub=A_ub,
+        b_ub=b_ub,
+        bounds=(0, None),
+        options={
+            "disp": True,
+            'maxiter': 1000000,
+            'bland': True,
+            'tol': 1e-6,
+        })
+    nonzeros = 0
+    print('Ran')
+    if res.success:
+        print('Result sample (%d elements)' % (len(res.x)))
+        plim = 3
+        for xi, x in enumerate(res.x):
+            nonzero = x >= 0.001
+            if nonzero:
+                nonzeros += 1
+            if nonzero and (verbose or (
+                (nonzeros < 100 or nonzeros % 20 == 0) and nonzeros <= plim)):
+                print('  % 4u  % 10.1f' % (xi, x))
+        print('Delay on %d / %d' % (nonzeros, len(res.x)))
+
+
+def run_min(Anp, b, verbose=False):
+    cols = len(Anp[0])
+
+    b_ub = b
+    A_ub = Anp
+
+    res = optimize.linprog(
+        c=[-1 for _i in range(cols)],
+        A_ub=A_ub,
+        b_ub=b_ub,
+        bounds=(0, None),
+        options={
+            "disp": True,
+            'maxiter': 1000000,
+            'bland': True,
+            'tol': 1e-6,
+        })
+    nonzeros = 0
+    print('Ran')
+    if res.success:
+        print('Result sample (%d elements)' % (len(res.x)))
+        plim = 3
+        for xi, x in enumerate(res.x):
+            nonzero = x >= 0.001
+            if nonzero:
+                nonzeros += 1
+            if nonzero and (verbose or (
+                (nonzeros < 100 or nonzeros % 20 == 0) and nonzeros <= plim)):
+                print('  % 4u  % 10.1f' % (xi, x))
+        print('Delay on %d / %d' % (nonzeros, len(res.x)))
+
+
+def run(verbose=False):
+    '''
+    1 * x0          =  10
+    1 * x0 + 1 * x1 = 100
+    1 * x0          =  40
+             2 * x1 = 140
+    '''
+    Anp = np.array([
+        [1, 0],
+        [1, 1],
+        [1, 0],
+        [0, 2],
+    ])
+    b = np.array([
+        10,
+        100,
+        40,
+        140,
+    ])
+    '''
+    Max
+    Optimization terminated successfully.
+             Current function value: 110.000000  
+             Iterations: 4
+    Ran
+    Result sample (2 elements)
+         0        40.0
+         1        70.0
+    Delay on 2 / 2
+    '''
+    print('Max')
+    run_max(Anp, b)
+    print('')
+    print('')
+    print('')
+    '''
+    Min
+    Optimization terminated successfully.
+             Current function value: -80.000000  
+             Iterations: 2
+    Ran
+    Result sample (2 elements)
+         0        10.0
+         1        70.0
+    Delay on 2 / 2
+    '''
+    print('Min')
+    run_min(Anp, b)
+
+
+def main():
+    import argparse
+
+    parser = argparse.ArgumentParser(description='Test')
+
+    parser.add_argument('--verbose', action='store_true', help='')
+    args = parser.parse_args()
+
+    run(verbose=args.verbose)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/fuzzers/007-timing/test_unique/.gitignore b/fuzzers/007-timing/minitest/test_unique/.gitignore
similarity index 100%
rename from fuzzers/007-timing/test_unique/.gitignore
rename to fuzzers/007-timing/minitest/test_unique/.gitignore
diff --git a/fuzzers/007-timing/test_unique/Makefile b/fuzzers/007-timing/minitest/test_unique/Makefile
similarity index 100%
rename from fuzzers/007-timing/test_unique/Makefile
rename to fuzzers/007-timing/minitest/test_unique/Makefile
diff --git a/fuzzers/007-timing/test_unique/README.md b/fuzzers/007-timing/minitest/test_unique/README.md
similarity index 100%
rename from fuzzers/007-timing/test_unique/README.md
rename to fuzzers/007-timing/minitest/test_unique/README.md
diff --git a/fuzzers/007-timing/test_unique/generate.sh b/fuzzers/007-timing/minitest/test_unique/generate.sh
similarity index 100%
rename from fuzzers/007-timing/test_unique/generate.sh
rename to fuzzers/007-timing/minitest/test_unique/generate.sh
diff --git a/fuzzers/007-timing/test_unique/generate.tcl b/fuzzers/007-timing/minitest/test_unique/generate.tcl
similarity index 100%
rename from fuzzers/007-timing/test_unique/generate.tcl
rename to fuzzers/007-timing/minitest/test_unique/generate.tcl
diff --git a/fuzzers/007-timing/test_unique/node_unique.py b/fuzzers/007-timing/minitest/test_unique/node_unique.py
similarity index 100%
rename from fuzzers/007-timing/test_unique/node_unique.py
rename to fuzzers/007-timing/minitest/test_unique/node_unique.py
diff --git a/fuzzers/007-timing/test_unique/perf_test.py b/fuzzers/007-timing/minitest/test_unique/perf_test.py
similarity index 100%
rename from fuzzers/007-timing/test_unique/perf_test.py
rename to fuzzers/007-timing/minitest/test_unique/perf_test.py
diff --git a/fuzzers/007-timing/test_unique/pip_unique.py b/fuzzers/007-timing/minitest/test_unique/pip_unique.py
similarity index 100%
rename from fuzzers/007-timing/test_unique/pip_unique.py
rename to fuzzers/007-timing/minitest/test_unique/pip_unique.py
diff --git a/fuzzers/007-timing/test_unique/top.v b/fuzzers/007-timing/minitest/test_unique/top.v
similarity index 100%
rename from fuzzers/007-timing/test_unique/top.v
rename to fuzzers/007-timing/minitest/test_unique/top.v
diff --git a/fuzzers/007-timing/test_unique/wire_unique.py b/fuzzers/007-timing/minitest/test_unique/wire_unique.py
similarity index 100%
rename from fuzzers/007-timing/test_unique/wire_unique.py
rename to fuzzers/007-timing/minitest/test_unique/wire_unique.py
diff --git a/fuzzers/007-timing/test_zero/README.md b/fuzzers/007-timing/minitest/test_zero/README.md
similarity index 100%
rename from fuzzers/007-timing/test_zero/README.md
rename to fuzzers/007-timing/minitest/test_zero/README.md
diff --git a/fuzzers/007-timing/test_zero/process.py b/fuzzers/007-timing/minitest/test_zero/process.py
similarity index 100%
rename from fuzzers/007-timing/test_zero/process.py
rename to fuzzers/007-timing/minitest/test_zero/process.py
diff --git a/fuzzers/007-timing/projects/corner.mk b/fuzzers/007-timing/projects/corner.mk
index da62dbd8..d7b27a83 100644
--- a/fuzzers/007-timing/projects/corner.mk
+++ b/fuzzers/007-timing/projects/corner.mk
@@ -4,7 +4,8 @@ TIMFUZ_DIR=$(XRAY_DIR)/fuzzers/007-timing
 CORNER=slow_max
 ALLOW_ZERO_EQN?=N
 BADPRJ_OK?=N
-BUILD_DIR?=build
+BUILD_DIR?=build/MUST_SET
+CSV_BASENAME=timing4i.csv
 
 all: $(BUILD_DIR)/$(CORNER)/timgrid-vc.json $(BUILD_DIR)/$(CORNER)/qor.txt
 
@@ -19,7 +20,7 @@ clean:
 .PHONY: all run clean
 
 $(BUILD_DIR)/$(CORNER):
-	mkdir $(BUILD_DIR)/$(CORNER)
+	mkdir -p $(BUILD_DIR)/$(CORNER)
 
 # parent should have built this
 $(BUILD_DIR)/checksub:
@@ -27,12 +28,12 @@ $(BUILD_DIR)/checksub:
 
 $(BUILD_DIR)/$(CORNER)/leastsq.csv: $(BUILD_DIR)/sub.json $(BUILD_DIR)/grouped.csv $(BUILD_DIR)/checksub $(BUILD_DIR)/$(CORNER)
 	# Create a rough timing model that approximately fits the given paths
-	python3 $(TIMFUZ_DIR)/solve_leastsq.py --sub-json $(BUILD_DIR)/sub.json $(BUILD_DIR)/grouped.csv --corner $(CORNER) --out $(BUILD_DIR)/$(CORNER)/leastsq.csv.tmp
+	python3 $(TIMFUZ_DIR)/solve_leastsq.py $(BUILD_DIR)/grouped.csv --corner $(CORNER) --out $(BUILD_DIR)/$(CORNER)/leastsq.csv.tmp
 	mv $(BUILD_DIR)/$(CORNER)/leastsq.csv.tmp $(BUILD_DIR)/$(CORNER)/leastsq.csv
 
 $(BUILD_DIR)/$(CORNER)/linprog.csv: $(BUILD_DIR)/$(CORNER)/leastsq.csv $(BUILD_DIR)/grouped.csv
 	# Tweak rough timing model, making sure all constraints are satisfied
-	ALLOW_ZERO_EQN=$(ALLOW_ZERO_EQN) python3 $(TIMFUZ_DIR)/solve_linprog.py --sub-json $(BUILD_DIR)/sub.json --bounds-csv $(BUILD_DIR)/$(CORNER)/leastsq.csv --massage $(BUILD_DIR)/grouped.csv --corner $(CORNER) --out $(BUILD_DIR)/$(CORNER)/linprog.csv.tmp
+	ALLOW_ZERO_EQN=$(ALLOW_ZERO_EQN) python3 $(TIMFUZ_DIR)/solve_linprog.py --bounds-csv $(BUILD_DIR)/$(CORNER)/leastsq.csv --massage $(BUILD_DIR)/grouped.csv --corner $(CORNER) --out $(BUILD_DIR)/$(CORNER)/linprog.csv.tmp
 	mv $(BUILD_DIR)/$(CORNER)/linprog.csv.tmp $(BUILD_DIR)/$(CORNER)/linprog.csv
 
 $(BUILD_DIR)/$(CORNER)/flat.csv: $(BUILD_DIR)/$(CORNER)/linprog.csv
@@ -46,6 +47,11 @@ $(BUILD_DIR)/$(CORNER)/timgrid-vc.json: $(BUILD_DIR)/$(CORNER)/flat.csv
 	python3 $(TIMFUZ_DIR)/tile_annotate.py --timgrid-s $(TIMFUZ_DIR)/timgrid/build/timgrid-s.json --out $(BUILD_DIR)/$(CORNER)/timgrid-vc.json $(BUILD_DIR)/$(CORNER)/flat.csv
 
 $(BUILD_DIR)/$(CORNER)/qor.txt: $(BUILD_DIR)/$(CORNER)/flat.csv
-	python3 $(TIMFUZ_DIR)/solve_qor.py --corner $(CORNER) --bounds-csv $(BUILD_DIR)/$(CORNER)/flat.csv specimen_*/timing3.csv >$(BUILD_DIR)/$(CORNER)/qor.txt.tmp
+ifeq ($(SOLVING),i)
+	python3 $(TIMFUZ_DIR)/solve_qor.py --corner $(CORNER) --bounds-csv $(BUILD_DIR)/$(CORNER)/flat.csv specimen_*/timing4i.csv >$(BUILD_DIR)/$(CORNER)/qor.txt.tmp
 	mv $(BUILD_DIR)/$(CORNER)/qor.txt.tmp $(BUILD_DIR)/$(CORNER)/qor.txt
+else
+    # FIXME
+	touch $(BUILD_DIR)/$(CORNER)/qor.txt
+endif
 
diff --git a/fuzzers/007-timing/projects/generate.sh b/fuzzers/007-timing/projects/generate.sh
index f8e6e094..a43fadcf 100644
--- a/fuzzers/007-timing/projects/generate.sh
+++ b/fuzzers/007-timing/projects/generate.sh
@@ -4,6 +4,13 @@ source ${XRAY_GENHEADER}
 TIMFUZ_DIR=$XRAY_DIR/fuzzers/007-timing
 
 timing_txt2csv () {
-    python3 $TIMFUZ_DIR/timing_txt2csv.py --speed-json $TIMFUZ_DIR/speed/build/speed.json --out timing3.csv timing3.txt
+    python3 $TIMFUZ_DIR/timing_txt2icsv.py --speed-json $TIMFUZ_DIR/speed/build/speed.json --out timing4i.csv.tmp timing4.txt
+    mv timing4i.csv.tmp timing4i.csv
+
+    python3 $TIMFUZ_DIR/timing_txt2scsv.py --speed-json $TIMFUZ_DIR/speed/build/speed.json --out timing4s.csv.tmp timing4.txt
+    mv timing4s.csv.tmp timing4s.csv
+
+    # delete really large file, see https://github.com/SymbiFlow/prjxray/issues/137
+    rm timing4.txt
 }
 
diff --git a/fuzzers/007-timing/projects/is.mk b/fuzzers/007-timing/projects/is.mk
new file mode 100644
index 00000000..5c419487
--- /dev/null
+++ b/fuzzers/007-timing/projects/is.mk
@@ -0,0 +1,74 @@
+# Interconnect and site (IS) high level aggregation
+# Creates corner data and aggregates them together
+
+TIMFUZ_DIR=$(XRAY_DIR)/fuzzers/007-timing
+SOLVING=i
+CSV_BASENAME=timing4$(SOLVING).csv
+BUILD_DIR?=build/MUST_SET
+SPECIMENS :=
+CSVS := $(addsuffix /$(CSV_BASENAME),$(SPECIMENS))
+RREF_CORNER=slow_max
+
+# Set ZERO elements to zero delay (as is expected they should be)
+RMZERO?=N
+
+RREF_ARGS=
+ifeq ($(RMZERO),Y)
+RREF_ARGS+=--rm-zero
+endif
+
+
+# FIXME: clean this up by generating targets from CORNERS
+
+# fast_max => build/i/fast_max/timgrid-vc.json
+TIMGRID_VCS=$(BUILD_DIR)/fast_max/timgrid-vc.json $(BUILD_DIR)/fast_min/timgrid-vc.json $(BUILD_DIR)/slow_max/timgrid-vc.json $(BUILD_DIR)/slow_min/timgrid-vc.json
+#TIMGRID_VCS=$(addsuffix /timgrid-vc.json,$(addprefix $(BUILD_DIR_I)/,$(CORNERS)))
+# make $(BUILD_DIR)/checksub first
+$(BUILD_DIR)/fast_max/timgrid-vc.json: $(BUILD_DIR)/checksub
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=fast_max
+$(BUILD_DIR)/fast_min/timgrid-vc.json: $(BUILD_DIR)/checksub
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=fast_min
+$(BUILD_DIR)/slow_max/timgrid-vc.json: $(BUILD_DIR)/checksub
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=slow_max
+$(BUILD_DIR)/slow_min/timgrid-vc.json: $(BUILD_DIR)/checksub
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=slow_min
+
+
+# Normally require all projects to complete
+# If BADPRJ_OK is allowed, only take projects that were successful
+# FIXME: couldn't get call to work
+exist_csvs = \
+        for f in $(CSVS); do \
+            if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then \
+                echo $$f; \
+            fi; \
+        done
+
+all: $(BUILD_DIR)/timgrid-v.json
+
+# rref should be the same regardless of corner
+$(BUILD_DIR)/sub.json: $(SPECIMENS_OK)
+	mkdir -p $(BUILD_DIR)
+	# Discover which variables can be separated
+	# This is typically the longest running operation
+	\
+	    csvs=$$(for f in $(CSVS); do if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then echo $$f; fi; done) ; \
+	    echo $$csvs ; \
+	    python3 $(TIMFUZ_DIR)/rref.py --corner $(RREF_CORNER) --simplify $(RREF_ARGS) --out $(BUILD_DIR)/sub.json.tmp $$csvs
+	mv $(BUILD_DIR)/sub.json.tmp $(BUILD_DIR)/sub.json
+
+$(BUILD_DIR)/grouped.csv: $(SPECIMENS_OK) $(BUILD_DIR)/sub.json
+	# Separate variables
+	\
+	    csvs=$$(for f in $(CSVS); do if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then echo $$f; fi; done) ; \
+	    python3 $(TIMFUZ_DIR)/csv_flat2group.py --sub-json $(BUILD_DIR)/sub.json --strict --out $(BUILD_DIR)/grouped.csv.tmp $$csvs
+	mv $(BUILD_DIR)/grouped.csv.tmp $(BUILD_DIR)/grouped.csv
+
+$(BUILD_DIR)/checksub: $(BUILD_DIR)/grouped.csv $(BUILD_DIR)/sub.json
+	# Verify sub.json makes a cleanly solvable solution with no non-pivot leftover
+	python3 $(TIMFUZ_DIR)/checksub.py --sub-json $(BUILD_DIR)/sub.json $(BUILD_DIR)/grouped.csv
+	touch $(BUILD_DIR)/checksub
+
+$(BUILD_DIR)/timgrid-v.json: $(TIMGRID_VCS)
+	python3 $(TIMFUZ_DIR)/timgrid_vc2v.py --out $(BUILD_DIR)/timgrid-v.json $(TIMGRID_VCS)
+
diff --git a/fuzzers/007-timing/projects/oneblinkw/generate.tcl b/fuzzers/007-timing/projects/oneblinkw/generate.tcl
index e7946556..19a3b799 100644
--- a/fuzzers/007-timing/projects/oneblinkw/generate.tcl
+++ b/fuzzers/007-timing/projects/oneblinkw/generate.tcl
@@ -43,5 +43,5 @@ proc build_design {} {
 }
 
 build_design
-write_info3
+write_info4
 
diff --git a/fuzzers/007-timing/projects/picorv32/generate.tcl b/fuzzers/007-timing/projects/picorv32/generate.tcl
index a928a3bd..56a2ebea 100644
--- a/fuzzers/007-timing/projects/picorv32/generate.tcl
+++ b/fuzzers/007-timing/projects/picorv32/generate.tcl
@@ -44,5 +44,5 @@ proc build_design {} {
 }
 
 build_design
-write_info3
+write_info4
 
diff --git a/fuzzers/007-timing/projects/placelut/generate.sh b/fuzzers/007-timing/projects/placelut/generate.sh
index fff71d31..40bc4550 100755
--- a/fuzzers/007-timing/projects/placelut/generate.sh
+++ b/fuzzers/007-timing/projects/placelut/generate.sh
@@ -7,5 +7,5 @@ TIMFUZ_DIR=$XRAY_DIR/fuzzers/007-timing
 
 python ../generate.py --sdx 4 --sdy 4  >top.v
 vivado -mode batch -source ../generate.tcl
-python3 $TIMFUZ_DIR/timing_txt2csv.py --speed-json $TIMFUZ_DIR/speed/build/speed.json --out timing3.csv timing3.txt
+python3 $TIMFUZ_DIR/timing_txt2csv.py --speed-json $TIMFUZ_DIR/speed/build/speed.json --out timing4.csv timing4.txt
 
diff --git a/fuzzers/007-timing/projects/placelut/generate.tcl b/fuzzers/007-timing/projects/placelut/generate.tcl
index 0b536169..11152586 100644
--- a/fuzzers/007-timing/projects/placelut/generate.tcl
+++ b/fuzzers/007-timing/projects/placelut/generate.tcl
@@ -43,5 +43,5 @@ proc build_design {} {
 }
 
 build_design
-write_info3
+write_info4
 
diff --git a/fuzzers/007-timing/projects/placelut_fb/generate.tcl b/fuzzers/007-timing/projects/placelut_fb/generate.tcl
index 0b536169..11152586 100644
--- a/fuzzers/007-timing/projects/placelut_fb/generate.tcl
+++ b/fuzzers/007-timing/projects/placelut_fb/generate.tcl
@@ -43,5 +43,5 @@ proc build_design {} {
 }
 
 build_design
-write_info3
+write_info4
 
diff --git a/fuzzers/007-timing/projects/placelut_ff_fb/generate.tcl b/fuzzers/007-timing/projects/placelut_ff_fb/generate.tcl
index 0b536169..11152586 100644
--- a/fuzzers/007-timing/projects/placelut_ff_fb/generate.tcl
+++ b/fuzzers/007-timing/projects/placelut_ff_fb/generate.tcl
@@ -43,5 +43,5 @@ proc build_design {} {
 }
 
 build_design
-write_info3
+write_info4
 
diff --git a/fuzzers/007-timing/projects/project.mk b/fuzzers/007-timing/projects/project.mk
index 4cced328..f21f803e 100644
--- a/fuzzers/007-timing/projects/project.mk
+++ b/fuzzers/007-timing/projects/project.mk
@@ -4,38 +4,26 @@
 N := 1
 SPECIMENS := $(addprefix specimen_,$(shell seq -f '%03.0f' $(N)))
 SPECIMENS_OK := $(addsuffix /OK,$(SPECIMENS))
-CSVS := $(addsuffix /timing3.csv,$(SPECIMENS))
 TIMFUZ_DIR=$(XRAY_DIR)/fuzzers/007-timing
-RREF_CORNER=slow_max
 # Allow an empty system of equations?
 # for testing only on small projects
 ALLOW_ZERO_EQN?=N
 # Constrained projects may fail to build
 # Set to Y to make a best effort to suck in the ones that did build
 BADPRJ_OK?=N
-# Set ZERO elements to zero delay (as is expected they should be)
-RMZERO?=N
 BUILD_DIR?=build
+# interconnect
+BUILD_DIR_I?=$(BUILD_DIR)/i
+# site
+BUILD_DIR_S?=$(BUILD_DIR)/s
 
-RREF_ARGS=
-ifeq ($(RMZERO),Y)
-RREF_ARGS+=--rm-zero
-endif
+CORNERS=fast_max fast_min slow_max slow_min
 
-TIMGRID_VCS=$(BUILD_DIR)/fast_max/timgrid-vc.json $(BUILD_DIR)/fast_min/timgrid-vc.json $(BUILD_DIR)/slow_max/timgrid-vc.json $(BUILD_DIR)/slow_min/timgrid-vc.json
+TIMGRID_V_I=$(BUILD_DIR_I)/timgrid-v.json
+TIMGRID_V_S=$(BUILD_DIR_S)/timgrid-v.json
 
 all: $(BUILD_DIR)/timgrid-v.json
 
-# make $(BUILD_DIR)/checksub first
-$(BUILD_DIR)/fast_max/timgrid-vc.json: $(BUILD_DIR)/checksub
-	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=fast_max
-$(BUILD_DIR)/fast_min/timgrid-vc.json: $(BUILD_DIR)/checksub
-	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=fast_min
-$(BUILD_DIR)/slow_max/timgrid-vc.json: $(BUILD_DIR)/checksub
-	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=slow_max
-$(BUILD_DIR)/slow_min/timgrid-vc.json: $(BUILD_DIR)/checksub
-	$(MAKE) -f $(TIMFUZ_DIR)/projects/corner.mk CORNER=slow_min
-
 $(SPECIMENS_OK):
 	bash generate.sh $(subst /OK,,$@) || (if [ "$(BADPRJ_OK)" != 'Y' ] ; then exit 1; fi; exit 0)
 	touch $@
@@ -52,38 +40,16 @@ clean:
 
 .PHONY: all run clean
 
-# Normally require all projects to complete
-# If BADPRJ_OK is allowed, only take projects that were successful
-# FIXME: couldn't get call to work
-exist_csvs = \
-        for f in $(CSVS); do \
-            if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then \
-                echo $$f; \
-            fi; \
-        done
+$(TIMGRID_V_I): $(SPECIMENS_OK)
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/is.mk BUILD_DIR=$(BUILD_DIR_I) SOLVING=i SPECIMENS=$(SPECIMENS) all
+i: $(TIMGRID_V_I)
 
-# rref should be the same regardless of corner
-$(BUILD_DIR)/sub.json: $(SPECIMENS_OK)
-	mkdir -p $(BUILD_DIR)
-	# Discover which variables can be separated
-	# This is typically the longest running operation
-	\
-	    csvs=$$(for f in $(CSVS); do if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then echo $$f; fi; done) ; \
-	    python3 $(TIMFUZ_DIR)/rref.py --corner $(RREF_CORNER) --simplify $(RREF_ARGS) --out $(BUILD_DIR)/sub.json.tmp $$csvs
-	mv $(BUILD_DIR)/sub.json.tmp $(BUILD_DIR)/sub.json
+$(TIMGRID_V_S): $(SPECIMENS_OK)
+	$(MAKE) -f $(TIMFUZ_DIR)/projects/is.mk BUILD_DIR=$(BUILD_DIR_S) SOLVING=s SPECIMENS=$(SPECIMENS) all
+s: $(TIMGRID_V_S)
 
-$(BUILD_DIR)/grouped.csv: $(SPECIMENS_OK) $(BUILD_DIR)/sub.json
-	# Separate variables
-	\
-	    csvs=$$(for f in $(CSVS); do if [ "$(BADPRJ_OK)" != 'Y' -o -f $$f ] ; then echo $$f; fi; done) ; \
-	    python3 $(TIMFUZ_DIR)/csv_flat2group.py --sub-json $(BUILD_DIR)/sub.json --strict --out $(BUILD_DIR)/grouped.csv.tmp $$csvs
-	mv $(BUILD_DIR)/grouped.csv.tmp $(BUILD_DIR)/grouped.csv
+.PHONY: i s
 
-$(BUILD_DIR)/checksub: $(BUILD_DIR)/grouped.csv $(BUILD_DIR)/sub.json
-	# Verify sub.json makes a cleanly solvable solution with no non-pivot leftover
-	python3 $(TIMFUZ_DIR)/checksub.py --sub-json $(BUILD_DIR)/sub.json $(BUILD_DIR)/grouped.csv
-	touch $(BUILD_DIR)/checksub
-
-$(BUILD_DIR)/timgrid-v.json: $(TIMGRID_VCS)
-	python3 $(TIMFUZ_DIR)/timgrid_vc2v.py --out $(BUILD_DIR)/timgrid-v.json $(TIMGRID_VCS)
+$(BUILD_DIR)/timgrid-v.json: $(TIMGRID_V_I) $(TIMGRID_V_S)
+	python3 $(TIMFUZ_DIR)/timgrid_vc2v.py --out $(BUILD_DIR)/timgrid-v.json $(TIMGRID_V_I) $(TIMGRID_V_S)
 
diff --git a/fuzzers/007-timing/projects/project.tcl b/fuzzers/007-timing/projects/project.tcl
index b1478201..9d45128e 100644
--- a/fuzzers/007-timing/projects/project.tcl
+++ b/fuzzers/007-timing/projects/project.tcl
@@ -1,166 +1,205 @@
-proc pin_info {pin} {
-    set cell [get_cells -of_objects $pin]
-    set bel [get_bels -of_objects $cell]
-    set site [get_sites -of_objects $bel]
-    return "$site $bel"
+# General notes:
+# Observed nets with 1 to 2 source cell pins
+#   2 example
+#   [get_pins -filter {DIRECTION == OUT} -of_objects $net]
+#   roi/dout_shr[0]_i_1/O: BEL, visible
+#   roi/dout_shr_reg[0]: no BEL, not visible, named after the net
+#   I don't understand what the relationship between these two is
+#   Maybe register retiming?
+# Observed nets with 0 to 1 source bel pins
+#   0 example: <const0>
+# Recommendation: assume there is at most one source BEL
+# Take that as the source BEL if it exists, otherwise don't do any source analysis
+
+# get_timing_paths vs get_net_delays
+# get_timing_paths is built on top of get_net_delays?
+# has some different info, but is fixed on the slow max corner
+# *possibly* reports slightly better info within a site, but would need to verify that
+
+# Things safe to assume:
+# -Each net has at least one delay?
+# -Cell exists for every delay path
+# -Each net has at least one destination BEL pin
+# Things not safe to assume
+# -Each net has at least one source BEL pin (ex: <const0>)
+
+
+proc list_format {l delim} {
+    set ret ""
+    set needspace 0
+    foreach x $l {
+        if $needspace {
+            set ret "$ret$delim$x"
+        } else {
+            set ret "$x"
+        }
+        set needspace 1
+    }
+    return $ret
 }
 
-proc pin_bel {pin} {
-    set cell [get_cells -of_objects $pin]
-    set bel [get_bels -of_objects $cell]
-    return $bel
+proc line_net_external {fp net src_site src_site_type src_site_pin src_bel src_bel_pin dst_site dst_site_type dst_site_pin dst_bel dst_bel_pin ico fast_max fast_min slow_max slow_min pips_out wires_out} {
+    puts $fp "NET,$net,$src_site,$src_site_type,$src_site_pin,$src_bel,$src_bel_pin,$dst_site,$dst_site_type,$dst_site_pin,$dst_bel,$dst_bel_pin,$ico,$fast_max,$fast_min,$slow_max,$slow_min,$pips_out,$wires_out"
 }
 
-# Changed to group wires and nodes
-# This allows tracing the full path along with pips
-proc write_info3 {} {
+proc line_net_internal {fp net site site_type src_bel src_bel_pin dst_bel dst_bel_pin ico fast_max fast_min slow_max slow_min} {
+    set src_site $site
+    set src_site_type $site_type
+    set src_site_pin ""
+
+    set dst_site $site
+    set dst_site_type $site_type
+    set dst_site_pin ""
+
+    set pips_out ""
+    set wires_out ""
+
+    puts $fp "NET,$net,$src_site,$src_site_type,$src_site_pin,$src_bel,$src_bel_pin,$dst_site,$dst_site_type,$dst_site_pin,$dst_bel,$dst_bel_pin,$ico,$fast_max,$fast_min,$slow_max,$slow_min,$pips_out,$wires_out"
+}
+
+proc write_info4 {} {
     set outdir "."
-    set fp [open "$outdir/timing3.txt" w]
+    set fp [open "$outdir/timing4.txt" w]
     # bel as site/bel, so don't bother with site
-    puts $fp "net src_bel dst_bel ico fast_max fast_min slow_max slow_min pips inodes wires"
+    puts $fp "linetype,net,src_site,src_site_type,src_site_pin,src_bel,src_bel_pin,dst_site,dst_site_type,dst_site_pin,dst_bel,dst_bel_pin,ico,fast_max,fast_min,slow_max,slow_min,pips,wires"
 
     set TIME_start [clock clicks -milliseconds]
-    set verbose 0
-    set equations 0
-    set site_src_nets 0
-    set site_dst_nets 0
+    set delays_net 0
+    set nets_no_src_cell 0
+    set nets_no_src_bel 0
+    set lines_no_int 0
+    set lines_some_int 0
     set neti 0
     set nets [get_nets -hierarchical]
+    #set nets [get_nets clk]
+    #set nets [get_nets roi/counter[0]_i_2_n_0]
     set nnets [llength $nets]
     foreach net $nets {
         incr neti
-        #if {$neti >= 10} {
-        #    puts "Debug break"
-        #    break
-        #}
 
         puts "Net $neti / $nnets: $net"
+
+        # there are some special places like on IOB where you may not have a cell source pin
+        # this is due to special treatment where BEL vs SITE are blurred
         # The semantics of get_pins -leaf is kind of odd
         # When no passthrough LUTs exist, it has no effect
         # When passthrough LUT present:
         # -w/o -leaf: some pins + passthrough LUT pins
         # -w/ -leaf: different pins + passthrough LUT pins
         # With OUT filter this seems to be sufficient
-        set src_pin [get_pins -leaf -filter {DIRECTION == OUT} -of_objects $net]
-        set src_bel [pin_bel $src_pin]
+        set src_cell_pins [get_pins -leaf -filter {DIRECTION == OUT} -of_objects $net]
+        if {$src_cell_pins eq ""} {
+            incr nets_no_src_cell
+            # ex: IOB internal bel net
+            puts "  SKIP: no source cell"
+            continue
+        }
+        # 0 to 2 of these
+        # Seems when 2 of them they basically have the same bel + cell
+        # Make a best effort and move forward
+        set src_cell_pin [lindex $src_cell_pins 0]
+        set src_cell [get_cells -of_objects $src_cell_pin]
+
+        # Only applicable if in a site
+        set src_bel [get_bels -of_objects $src_cell]
+        if {$src_bel eq ""} {
+            # just throw out cases where source site doesn't exist
+            # these are very special, don't really have timing info anyway
+            # rework these later if they become problematic
+            incr nets_no_src_bel
+            puts "  SKIP: no source bel"
+            continue
+        }
+
+        set src_bel_pin [get_bel_pins -of_objects $src_cell_pin]
         set src_site [get_sites -of_objects $src_bel]
-        # Only one net driver
-        set src_site_pins [get_site_pins -filter {DIRECTION == OUT} -of_objects $net]
+        set src_site_type [get_property SITE_TYPE $src_site]
+        # optional
+        set src_site_pin [get_site_pins -of_objects $src_cell_pin]
 
-        # Sometimes this is empty for reasons that escape me
-        # Emitting direction doesn't help
-        if {[llength $src_site_pins] < 1} {
-            if $verbose {
-                puts "    Ignoring site internal net"
-            }
-            incr site_src_nets
-            continue
-        }
-        set dst_site_pins_net [get_site_pins -filter {DIRECTION == IN} -of_objects $net]
-        if {[llength $dst_site_pins_net] < 1} {
-            puts "  Skipping site internal source net"
-            incr site_dst_nets
-            continue
-        }
-        foreach src_site_pin $src_site_pins {
-            if $verbose {
-                puts "Source: $src_pin at site $src_site:$src_bel, spin $src_site_pin"
+        # Report delays with and without interconnect only
+        foreach ico "0 1" {
+            if $ico {
+                set delays [get_net_delays -interconnect_only -of_objects $net]
+            } else {
+                set delays [get_net_delays -of_objects $net]
             }
+            set delays_net [expr "$delays_net + [llength $delays]"]
+            puts $fp "GROUP,$ico,[llength $delays]"
+            foreach delay $delays {
+                #set delaystr [get_property NAME $delay]
 
-            # Run with and without interconnect only
-            foreach ico "0 1" {
-                set ico_flag ""
-                if $ico {
-                    set ico_flag "-interconnect_only"
-                    set delays [get_net_delays $ico_flag -of_objects $net]
+                set fast_max [get_property "FAST_MAX" $delay]
+                set fast_min [get_property "FAST_MIN" $delay]
+                set slow_max [get_property "SLOW_MAX" $delay]
+                set slow_min [get_property "SLOW_MIN" $delay]
+
+                # Does this always exist?
+                set dst_cell_pin_str [get_property TO_PIN $delay]
+                set dst_cell_pin [get_pins $dst_cell_pin_str]
+                set dst_cell [get_cells -of_objects $dst_cell_pin]
+                set dst_bel [get_bels -of_objects $dst_cell]
+                # WARNING: when there is a passthrough LUT, this can be multiple values
+                # (one for the real dest pin, and one for the passthrough lut input)
+                set dst_bel_pin [get_bel_pins -of_objects $dst_cell_pin]
+                set dst_site [get_sites -of_objects $dst_bel]
+                set dst_site_type [get_property SITE_TYPE $dst_site]
+                # optional
+                set dst_site_pin [get_site_pins -of_objects $dst_cell_pin]
+
+                # No fabric on this net?
+                # don't try querying sites and such
+                if {[get_nodes -of_objects $net] eq ""} {
+                    if {$src_site ne $dst_site} {
+                        puts "ERROR: site mismatch"
+                        return
+                    }
+                    if {$src_site_type ne $dst_site_type} {
+                        puts "ERROR: site mismatch"
+                        return
+                    }
+
+                    # Already have everything we could query
+                    # Just output
+                    incr lines_no_int
+                    line_net_internal $fp $net $src_site $src_site_type $src_bel $src_bel_pin $dst_bel $dst_bel_pin $ico $fast_max $fast_min $slow_max $slow_min
+                # At least some fabric exists
+                # Does dest BEL exist but not source BEL?
+                } elseif {$src_bel eq ""} {
+                    puts "ERROR: should have been filtered"
+                    return
+                # Ideally query from and to cell pins
                 } else {
-                    set delays [get_net_delays -of_objects $net]
-                }
-                foreach delay $delays {
-                    set delaystr [get_property NAME $delay]
-                    set dst_pins [get_property TO_PIN $delay]
-                    set dst_pin [get_pins $dst_pins]
-                    #puts "  $delaystr: $src_pin => $dst_pin"
-                    set dst_bel [pin_bel $dst_pin]
-                    set dst_site [get_sites -of_objects $dst_bel]
-                    if $verbose {
-                        puts "  Dest: $dst_pin at site $dst_site:$dst_bel"
+                    # Nested list delimination precedence: ",|:"
+
+                    # Pips in between
+                    # Walk net, looking for interesting elements in between
+                    #  -from <args> - (Optional) Defines the starting points of the pips to get
+                    #  from wire or site_pin
+                    set pips [get_pips -of_objects $net -from $src_site_pin -to $dst_site_pin]
+                    # Write pips w/ speed index
+                    foreach pip $pips {
+                        set speed_index [get_property SPEED_INDEX $pip]
+                        lappend pips_out "$pip:$speed_index"
+                    }
+                    set pips_out [list_format "$pips_out" "|"]
+
+                    set nodes [get_nodes -of_objects $net -from $src_site_pin -to $dst_site_pin]
+                    if {$nodes eq ""} {
+                        puts "ERROR: no nodes"
+                        return
                     }
 
-                    set dst_site_pins [get_site_pins -of_objects $dst_pin]
-                    # Some nets are internal
-                    # But should this happen on dest if we've already filtered source?
-                    if {"$dst_site_pins" eq ""} {
-                        continue
+                    set wires [get_wires -of_objects $nodes]
+                    # Write wires
+                    foreach wire $wires {
+                        set speed_index [get_property SPEED_INDEX $wire]
+                        lappend wires_out "$wire:$speed_index"
                     }
-                    # Also apparantly you can have multiple of these as well
-                    foreach dst_site_pin $dst_site_pins {
-                        set fast_max [get_property "FAST_MAX" $delay]
-                        set fast_min [get_property "FAST_MIN" $delay]
-                        set slow_max [get_property "SLOW_MAX" $delay]
-                        set slow_min [get_property "SLOW_MIN" $delay]
+                    set wires_out [list_format "$wires_out" "|"]
 
-                        # Want:
-                        # Site / BEL at src
-                        # Site / BEL at dst
-                        # Pips in between
-                        # Walk net, looking for interesting elements in between
-                        set pips [get_pips -of_objects $net -from $src_site_pin -to $dst_site_pin]
-                        if $verbose {
-                            foreach pip $pips {
-                                puts "    PIP $pip"
-                            }
-                        }
-                        set nodes [get_nodes -of_objects $net -from $src_site_pin -to $dst_site_pin]
-                        #set wires [get_wires -of_objects $net -from $src_site_pin -to $dst_site_pin]
-                        set wires [get_wires -of_objects $nodes]
-
-                        # puts $fp "$net $src_bel $dst_bel $ico $fast_max $fast_min $slow_max $slow_min $pips"
-                        puts -nonewline $fp "$net $src_bel $dst_bel $ico $fast_max $fast_min $slow_max $slow_min"
-        
-                        # Write pips w/ speed index
-                        puts -nonewline $fp " "
-                        set needspace 0
-                        foreach pip $pips {
-                            if $needspace {
-                                puts -nonewline $fp "|"
-                            }
-                            set speed_index [get_property SPEED_INDEX $pip]
-                            puts -nonewline $fp "$pip:$speed_index"
-                            set needspace 1
-                        }
-
-                        # Write nodes
-                        #set nodes_str [string map {" " "|"} $nodes]
-                        #puts -nonewline $fp " $nodes_str"
-                        puts -nonewline $fp " "
-                        set needspace 0
-                        foreach node $nodes {
-                            if $needspace {
-                                puts -nonewline $fp "|"
-                            }
-                            set nwires [llength [get_wires -of_objects $node]]
-                            puts -nonewline $fp "$node:$nwires"
-                            set needspace 1
-                        }
-
-                        # Write wires
-                        puts -nonewline $fp " "
-                        set needspace 0
-                        foreach wire $wires {
-                            if $needspace {
-                                puts -nonewline $fp "|"
-                            }
-                            set speed_index [get_property SPEED_INDEX $wire]
-                            puts -nonewline $fp "$wire:$speed_index"
-                            set needspace 1
-                        }
-
-                        puts $fp ""
-
-                        incr equations
-                        break
-                    }
+                    incr lines_some_int
+                    line_net_external $fp $net $src_site $src_site_type $src_site_pin $src_bel $src_bel_pin $dst_site $dst_site_type $dst_site_pin $dst_bel $dst_bel_pin $ico $fast_max $fast_min $slow_max $slow_min $pips_out $wires_out
                 }
             }
         }
@@ -168,7 +207,16 @@ proc write_info3 {} {
     close $fp
     set TIME_taken [expr [clock clicks -milliseconds] - $TIME_start]
     puts "Took ms: $TIME_taken"
-    puts "Generated $equations equations"
-    puts "Skipped $site_src_nets (+ $site_dst_nets) site nets"
+    puts "Checked $delays_net delays"
+    puts "Nets: $nnets"
+    puts "  Skipped (no source cell): $nets_no_src_cell"
+    puts "  Skipped (no source bel): $nets_no_src_bel"
+    puts "Lines"
+    puts "  No interconnect: $lines_no_int"
+    puts "  Has interconnect: $lines_some_int"
 }
 
+# for debugging
+# source ../project.tcl
+# write_info4
+
diff --git a/fuzzers/007-timing/rref.py b/fuzzers/007-timing/rref.py
index be13c805..7d6a449b 100644
--- a/fuzzers/007-timing/rref.py
+++ b/fuzzers/007-timing/rref.py
@@ -73,7 +73,7 @@ class State(object):
     def load(fn_ins, simplify=False, corner=None, rm_zero=False):
         zero_names = OrderedSet()
 
-        Ads, b = loadc_Ads_b(fn_ins, corner=corner, ico=True)
+        Ads, b = loadc_Ads_b(fn_ins, corner=corner)
         if rm_zero:
             zero_names = rm_zero_cols(Ads)
         if simplify:
@@ -223,13 +223,13 @@ def main():
         default='build_speed/speed.json',
         help='Provides speed index to name translation')
     parser.add_argument('--out', help='Output sub.json substitution result')
-    parser.add_argument('fns_in', nargs='*', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='*', help='timing4i.csv input files')
     args = parser.parse_args()
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     try:
         run(
diff --git a/fuzzers/007-timing/solve_leastsq.py b/fuzzers/007-timing/solve_leastsq.py
index 953c4dcf..3e6f5742 100644
--- a/fuzzers/007-timing/solve_leastsq.py
+++ b/fuzzers/007-timing/solve_leastsq.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-from timfuz import Benchmark, load_sub, corner_s2i, acorner2csv
+from timfuz import Benchmark, load_sub
 import timfuz
 import numpy as np
 import math
@@ -22,11 +22,20 @@ def mkestimate(Anp, b):
     x0 = np.array([1e3 for _x in range(cols)])
     for row_np, row_b in zip(Anp, b):
         for coli, val in enumerate(row_np):
-            if val:
-                # Scale by number occurances
-                ub = row_b / val
-                if ub >= 0:
-                    x0[coli] = min(x0[coli], ub)
+            # favor non-trivial values
+            if val <= 0:
+                continue
+            # Scale by number occurances
+            ub = row_b / val
+            if ub <= 0:
+                continue
+            if x0[coli] == 0:
+                x0[coli] = ub
+            else:
+                x0[coli] = min(x0[coli], ub)
+    # reject solutions that don't provide a seed value
+    # these lead to bad optimizations
+    assert sum(x0) != 0
     return x0
 
 
@@ -119,14 +128,14 @@ def main():
     parser.add_argument('--corner', required=True, default="slow_max", help='')
     parser.add_argument(
         '--out', default=None, help='output timing delay .json')
-    parser.add_argument('fns_in', nargs='+', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='+', help='timing4i.csv input files')
     args = parser.parse_args()
     # Store options in dict to ease passing through functions
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     sub_json = None
     if args.sub_json:
diff --git a/fuzzers/007-timing/solve_linprog.py b/fuzzers/007-timing/solve_linprog.py
index 0bb0dd6f..40586f5e 100644
--- a/fuzzers/007-timing/solve_linprog.py
+++ b/fuzzers/007-timing/solve_linprog.py
@@ -162,14 +162,14 @@ def main():
     parser.add_argument('--corner', required=True, default="slow_max", help='')
     parser.add_argument(
         '--out', default=None, help='output timing delay .json')
-    parser.add_argument('fns_in', nargs='+', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='+', help='timing4i.csv input files')
     args = parser.parse_args()
     # Store options in dict to ease passing through functions
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     sub_json = None
     if args.sub_json:
diff --git a/fuzzers/007-timing/solve_qor.py b/fuzzers/007-timing/solve_qor.py
index d3bb1eea..5a0bcf17 100644
--- a/fuzzers/007-timing/solve_qor.py
+++ b/fuzzers/007-timing/solve_qor.py
@@ -6,7 +6,7 @@ import numpy as np
 
 def run(fns_in, corner, bounds_csv, verbose=False):
     print('Loading data')
-    Ads, borig = loadc_Ads_b(fns_in, corner, ico=True)
+    Ads, borig = loadc_Ads_b(fns_in, corner)
 
     bounds = load_bounds(bounds_csv, corner)
     # verify is flattened
@@ -37,14 +37,14 @@ def main():
         '--bounds-csv',
         required=True,
         help='Previous solve result starting point')
-    parser.add_argument('fns_in', nargs='+', help='timing3.csv input files')
+    parser.add_argument('fns_in', nargs='+', help='timing4i.csv input files')
     args = parser.parse_args()
     # Store options in dict to ease passing through functions
     bench = Benchmark()
 
     fns_in = args.fns_in
     if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.csv')
+        fns_in = glob.glob('specimen_*/timing4i.csv')
 
     try:
         run(
diff --git a/fuzzers/007-timing/tile_annotate.py b/fuzzers/007-timing/tile_annotate.py
index af3d3d2a..e989d9a2 100644
--- a/fuzzers/007-timing/tile_annotate.py
+++ b/fuzzers/007-timing/tile_annotate.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 
 import timfuz
-from timfuz import loadc_Ads_bs, Ads2bounds
+from timfuz import loadc_Ads_bs, Ads2bounds, PREFIX_W, PREFIX_P, PREFIX_SW_EI, PREFIX_SW_EO, PREFIX_SW_I, sw_ei_s2vals, sw_eo_s2vals, sw_i_s2vals
 
 import sys
 import os
@@ -9,22 +9,117 @@ import time
 import json
 
 
+def add_pip_wire(tilej, bounds, verbose=False):
+    '''
+    We know all possible pips and wires from tilej
+    Iterate over them and see if a result was generated
+    '''
+    used_bounds = set()
+
+    for tile in tilej['tiles'].values():
+
+        def addk(pws, prefix, k, v):
+            variable = prefix + ':' + v
+            val = bounds.get(variable, None)
+            # print(variable, val)
+            if val:
+                used_bounds.add(variable)
+            else:
+                val = [None, None, None, None]
+            pws[k] = val
+
+        pips = tile['pips']
+        for k, v in pips.items():
+            #pips[k] = bounds.get('PIP_' + v, [None, None, None, None])
+            addk(pips, PREFIX_P, k, v)
+
+        wires = tile['wires']
+        for k, v in wires.items():
+            #wires[k] = bounds.get('WIRE_' + v, [None, None, None, None])
+            addk(wires, PREFIX_W, k, v)
+
+    # verify all the variables that should be used were applied
+    # ...except tilecon may be an ROI and we solved everything
+    print(
+        "Interconnect: %u / %u variables used" %
+        (len(used_bounds), len(bounds)))
+    if verbose:
+        print('Remainder: %s' % (set(bounds.keys()) - used_bounds))
+
+
+def add_sites(tilej, bounds):
+    # XXX: no source of truth currently
+    # is there a way we could get this?
+    # Naming discussion https://github.com/SymbiFlow/prjxray/pull/126
+
+    sitej = tilej.setdefault('sites', {})
+
+    def add_ei():
+        for variable, bound in bounds[PREFIX_SW_EI].items():
+            site_type, src_site_pin, dst_bel_type, dst_bel_pin = sw_ei_s2vals(
+                variable)
+            # ex: SLICEL:AX->AFF.D
+            k = (
+                '%s:%s->%s.%s' %
+                (site_type, src_site_pin, dst_bel_type, dst_bel_pin))
+            sitej.setdefault(site_type, {})[k] = bound
+
+    def add_eo():
+        for variable, bound in bounds[PREFIX_SW_EO].items():
+            site_type, src_bel_type, src_bel_pin, dst_site_pin = sw_eo_s2vals(
+                variable)
+            # ex: SLICEL:AFF.Q->AQ
+            k = (
+                '%s:%s.%s->%s' %
+                (site_type, src_bel_type, src_bel_pin, dst_site_pin))
+            sitej.setdefault(site_type, {})[k] = bound
+
+    def add_i():
+        for variable, bound in bounds[PREFIX_SW_I].items():
+            site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin = sw_i_s2vals(
+                variable)
+            # ex: SLICEL:LUT6.O2->AFF.D
+            k = (
+                '%s:%s.%s->%s.%s' %
+                (site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin))
+            sitej.setdefault(site_type, {})[k] = bound
+
+    add_ei()
+    add_eo()
+    add_i()
+    print('Sites: added %u sites' % len(sitej))
+    print('Added site wires')
+    print('  Site external in: %u' % len(bounds[PREFIX_SW_EI]))
+    print('  Site external out: %u' % len(bounds[PREFIX_SW_EO]))
+    print('  Site internal: %u' % len(bounds[PREFIX_SW_I]))
+
+
+def sep_bounds(bounds):
+    pw = {}
+    sites = {PREFIX_SW_EI: {}, PREFIX_SW_EO: {}, PREFIX_SW_I: {}}
+    for k, v in bounds.items():
+        prefix = k.split(':')[0]
+        if prefix in (PREFIX_W, PREFIX_P):
+            pw[k] = v
+        elif prefix in (PREFIX_SW_EI, PREFIX_SW_EO, PREFIX_SW_I):
+            sites[prefix][k] = v
+        else:
+            assert 0, 'Unknown delay: %s %s' % (k, prefix)
+    return pw, sites
+
+
 def run(fns_in, fnout, tile_json_fn, verbose=False):
     # modified in place
     tilej = json.load(open(tile_json_fn, 'r'))
 
     for fnin in fns_in:
-        Ads, bs = loadc_Ads_bs([fnin], ico=True)
+        Ads, bs = loadc_Ads_bs([fnin])
         bounds = Ads2bounds(Ads, bs)
+        bounds_pw, bounds_sites = sep_bounds(bounds)
+        print(len(bounds), len(bounds_pw), len(bounds_sites))
 
-        for tile in tilej['tiles'].values():
-            pips = tile['pips']
-            for k, v in pips.items():
-                pips[k] = bounds.get('PIP_' + v, [None, None, None, None])
-
-            wires = tile['wires']
-            for k, v in wires.items():
-                wires[k] = bounds.get('WIRE_' + v, [None, None, None, None])
+        add_pip_wire(tilej, bounds_pw)
+        add_sites(tilej, bounds_sites)
 
     timfuz.tilej_stats(tilej)
 
diff --git a/fuzzers/007-timing/timfuz.py b/fuzzers/007-timing/timfuz.py
index 7e5a970e..d380e525 100644
--- a/fuzzers/007-timing/timfuz.py
+++ b/fuzzers/007-timing/timfuz.py
@@ -17,6 +17,51 @@ import collections
 
 from benchmark import Benchmark
 
+# prefix to make easier to track
+# models do not overlap between PIPs and WIREs
+PREFIX_W = 'WIRE'
+PREFIX_P = 'PIP'
+# extneral site wire (ie site a to b)
+PREFIX_SW_EI = 'SITEW-EI'
+PREFIX_SW_EO = 'SITEW-EO'
+# internal site wire (ie bel a to b within a site)
+PREFIX_SW_I = 'SITEW-I'
+
+
+def sw_ei_vals2s(site_type, src_site_pin, dst_bel, dst_bel_pin):
+    '''Pack site wire components into a variable string'''
+    return '%s:%s:%s:%s:%s' % (
+        PREFIX_SW_EI, site_type, src_site_pin, dst_bel, dst_bel_pin)
+
+
+def sw_ei_s2vals(s):
+    prefix, site_type, src_site_pin, dst_bel, dst_bel_pin = s.split(':')
+    assert prefix == PREFIX_SW_EI
+    return site_type, src_site_pin, dst_bel, dst_bel_pin
+
+
+def sw_eo_vals2s(site_type, src_bel, src_bel_pin, dst_site_pin):
+    return '%s:%s:%s:%s:%s' % (
+        PREFIX_SW_EO, site_type, src_bel, src_bel_pin, dst_site_pin)
+
+
+def sw_eo_s2vals(s):
+    prefix, site_type, src_bel, src_bel_pin, dst_site_pin = s.split(':')
+    assert prefix == PREFIX_SW_EO
+    return site_type, src_bel, src_bel_pin, dst_site_pin
+
+
+def sw_i_vals2s(site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin):
+    return '%s:%s:%s:%s:%s:%s' % (
+        PREFIX_SW_I, site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin)
+
+
+def sw_i_s2vals(s):
+    prefix, site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin = s.split(
+        ':')
+    assert prefix == PREFIX_SW_I
+    return site_type, src_bel, src_bel_pin, dst_bel, dst_bel_pin
+
 
 # Equations are filtered out until nothing is left
 class SimplifiedToZero(Exception):
@@ -524,11 +569,14 @@ def loadc_Ads_mkb(fns, mkb, filt):
 def loadc_Ads_b(fns, corner, ico=None):
     corner = corner or "slow_max"
     corneri = corner_s2i[corner]
-
+    '''
     if ico is not None:
         filt = lambda ico_, corners, vars: ico_ == ico
     else:
         filt = lambda ico_, corners, vars: True
+    '''
+    assert ico is None, 'ICO filtering moved to higher levels'
+    filt = lambda ico_, corners, vars: True
 
     def mkb(val):
         return val[corneri]
@@ -537,10 +585,14 @@ def loadc_Ads_b(fns, corner, ico=None):
 
 
 def loadc_Ads_bs(fns, ico=None):
+    '''
     if ico is not None:
         filt = lambda ico_, corners, vars: ico_ == ico
     else:
         filt = lambda ico_, corners, vars: True
+    '''
+    assert ico is None, 'ICO filtering moved to higher levels'
+    filt = lambda ico_, corners, vars: True
 
     def mkb(val):
         return val
@@ -730,35 +782,63 @@ def corners2csv(bs):
 
 
 def tilej_stats(tilej):
-    stats = {}
-    for etype in ('pips', 'wires'):
-        tm = stats.setdefault(etype, {})
-        tm['net'] = 0
-        tm['solved'] = [0, 0, 0, 0]
-        tm['covered'] = [0, 0, 0, 0]
-
-    for tile in tilej['tiles'].values():
+    def tile_stats():
+        stats = {}
         for etype in ('pips', 'wires'):
-            pips = tile[etype]
-            for k, v in pips.items():
-                stats[etype]['net'] += 1
-                for i in range(4):
-                    if pips[k][i]:
-                        stats[etype]['solved'][i] += 1
-                    if pips[k][i] is not None:
-                        stats[etype]['covered'][i] += 1
+            tm = stats.setdefault(etype, {})
+            tm['net'] = 0
+            tm['solved'] = [0, 0, 0, 0]
+            tm['covered'] = [0, 0, 0, 0]
+
+        for tile in tilej['tiles'].values():
+            for etype in ('pips', 'wires'):
+                pips = tile[etype]
+                for k, v in pips.items():
+                    stats[etype]['net'] += 1
+                    for i in range(4):
+                        if pips[k][i]:
+                            stats[etype]['solved'][i] += 1
+                        if pips[k][i] is not None:
+                            stats[etype]['covered'][i] += 1
+        return stats
+
+    def site_stats():
+        sitesj = tilej['sites']
+        ret = {
+            'sites': len(sitesj),
+            'wires': sum([len(wiresj) for wiresj in sitesj.values()]),
+            'wires_solved': {},
+        }
+        for corneri in corner_s2i.values():
+            ret['wires_solved'][corneri] = sum(
+                [
+                    sum(
+                        [
+                            1 if site_wire[corneri] else 0
+                            for site_wire in sitej.values()
+                        ])
+                    for sitej in sitesj.values()
+                ])
+        return ret
+
+    tstats = tile_stats()
+    sstats = site_stats()
 
     for corner, corneri in corner_s2i.items():
         print('Corner %s' % corner)
         for etype in ('pips', 'wires'):
-            net = stats[etype]['net']
-            solved = stats[etype]['solved'][corneri]
-            covered = stats[etype]['covered'][corneri]
+            net = tstats[etype]['net']
+            solved = tstats[etype]['solved'][corneri]
+            covered = tstats[etype]['covered'][corneri]
             print(
                 '  %s: %u / %u solved, %u / %u covered' %
                 (etype, solved, net, covered, net))
+        print(
+            '  sites: %u sites w/ %u solved / %u covered site wires' % (
+                sstats['sites'], sstats['wires_solved'][corneri],
+                sstats['wires']))
 
 
-def load_bounds(bounds_csv, corner, ico=True):
-    Ads, b = loadc_Ads_b([bounds_csv], corner, ico=ico)
+def load_bounds(bounds_csv, corner):
+    Ads, b = loadc_Ads_b([bounds_csv], corner)
     return Ads2bounds(Ads, b)
diff --git a/fuzzers/007-timing/timfuz_massage.py b/fuzzers/007-timing/timfuz_massage.py
index 90d318f3..d64853c2 100644
--- a/fuzzers/007-timing/timfuz_massage.py
+++ b/fuzzers/007-timing/timfuz_massage.py
@@ -220,7 +220,9 @@ def derive_eq_by_col(Ads, b_ub, verbose=0, keep_orig=True):
 
 
 # iteratively increasing column limit until all columns are added
-def massage_equations(Ads, b, verbose=False, corner=None):
+def massage_equations(
+        Ads, b, verbose=False, corner=None, iter_lim=1, col_lim=100000):
+    #col_lim = 15
     '''
     Subtract equations from each other to generate additional constraints
     Helps provide additional guidance to solver for realistic delays
@@ -262,7 +264,6 @@ def massage_equations(Ads, b, verbose=False, corner=None):
 
     # Each iteration one more column is allowed until all columns are included
     # (and the system is stable)
-    col_lim = 15
     di = 0
     while True:
         print
@@ -298,13 +299,13 @@ def massage_equations(Ads, b, verbose=False, corner=None):
         col_dist(Ads, 'derive done iter %d, lim %d' % (di, col_lim), lim=12)
 
         rows = len(Ads)
+        di += 1
+        dend = len(b)
         # possible that a new equation was generated and taken away, but close enough
-        if n_orig == len(b) and col_lim >= cols:
+        if n_orig == len(b) and col_lim >= cols or di >= iter_lim:
             break
         col_lim += col_lim / 5
-        di += 1
 
-        dend = len(b)
         print('')
         print('Derive net: %d => %d' % (dstart, dend))
         print('')
diff --git a/fuzzers/007-timing/timfuz_solve.py b/fuzzers/007-timing/timfuz_solve.py
index 4cded620..3e09cf07 100644
--- a/fuzzers/007-timing/timfuz_solve.py
+++ b/fuzzers/007-timing/timfuz_solve.py
@@ -150,7 +150,10 @@ def solve_save(outfn, xvals, names, corner, save_zero=True, verbose=False):
     print(
         'Wrote: %u / %u constrained delays, %u zeros' %
         (nonzeros, len(names), zeros))
-    assert nonzeros, 'Failed to estimate delay'
+    # max only...min corner seems to like 0
+    # see https://github.com/SymbiFlow/prjxray/issues/136
+    if 'max' in corner:
+        assert nonzeros, 'Failed to estimate delay'
 
 
 def run(
@@ -165,7 +168,7 @@ def run(
         verbose=False,
         **kwargs):
     print('Loading data')
-    Ads, b = loadc_Ads_b(fns_in, corner, ico=True)
+    Ads, b = loadc_Ads_b(fns_in, corner)
 
     # Remove duplicate rows
     # is this necessary?
@@ -193,7 +196,7 @@ def run(
     Used primarily for multiple optimization passes, such as different algorithms or additional constraints
     '''
     if bounds_csv:
-        Ads2, b2 = loadc_Ads_b([bounds_csv], corner, ico=True)
+        Ads2, b2 = loadc_Ads_b([bounds_csv], corner)
         bounds = Ads2bounds(Ads2, b2)
         assert len(bounds), 'Failed to load bounds'
         rows_old = len(Ads)
diff --git a/fuzzers/007-timing/timgrid_vc2v.py b/fuzzers/007-timing/timgrid_vc2v.py
index 8c188d81..8cb19162 100644
--- a/fuzzers/007-timing/timgrid_vc2v.py
+++ b/fuzzers/007-timing/timgrid_vc2v.py
@@ -23,7 +23,31 @@ corner2minmax = {
 }
 
 
-def build_tilejo(fnins):
+def merge_bdict(vi, vo):
+    '''
+    vi: input dictionary
+    vo: output dictionary
+    values are corner delay 4 tuples
+    '''
+
+    for name, bis in vi.items():
+        bos = vo.get(name, [None, None, None, None])
+        for cornerk, corneri in corner_s2i.items():
+            bo = bos[corneri]
+            bi = bis[corneri]
+            # no new data
+            if bi is None:
+                pass
+            # no previous data
+            elif bo is None:
+                bos[corneri] = bi
+            # combine
+            else:
+                minmax = corner2minmax[cornerk]
+                bos[corneri] = minmax(bi, bo)
+
+
+def merge_tiles(tileji, tilejo):
     '''
     {
         "tiles": {
@@ -38,36 +62,37 @@ def build_tilejo(fnins):
                     ],
     '''
 
-    tilejo = {"tiles": {}}
+    for tilek, tilevi in tileji.items():
+        # No previous data? Copy
+        tilevo = tilejo.get(tilek, None)
+        if tilevo is None:
+            tilejo[tilek] = tilevi
+        # Otherwise combine
+        else:
+            merge_bdict(tilevi['pips'], tilevo['pips'])
+            merge_bdict(tilevi['wires'], tilevo['wires'])
+
+
+def merge_sites(siteji, sitejo):
+    for k, vi in siteji.items():
+        vo = sitejo.get(k, None)
+        # No previous data? Copy
+        if vo is None:
+            sitejo[k] = vi
+        # Otherwise combine
+        else:
+            merge_bdict(vi, vo)
+
+
+def build_tilejo(fnins):
+    # merge all inputs into blank output
+    tilejo = {"tiles": {}, "sites": {}}
     for fnin in fnins:
         tileji = json.load(open(fnin, 'r'))
-        for tilek, tilevi in tileji['tiles'].items():
-            # No previous data? Copy
-            tilevo = tilejo['tiles'].get(tilek, None)
-            if tilevo is None:
-                tilejo['tiles'][tilek] = tilevi
-            # Otherwise combine
-            else:
 
-                def process_type(etype):
-                    for pipk, pipvi in tilevi[etype].items():
-                        pipvo = tilevo[etype][pipk]
-                        for cornerk, corneri in corner_s2i.items():
-                            cornervo = pipvo[corneri]
-                            cornervi = pipvi[corneri]
-                            # no new data
-                            if cornervi is None:
-                                pass
-                            # no previous data
-                            elif cornervo is None:
-                                pipvo[corneri] = cornervi
-                            # combine
-                            else:
-                                minmax = corner2minmax[cornerk]
-                                pipvo[corneri] = minmax(cornervi, cornervo)
+        merge_tiles(tileji['tiles'], tilejo['tiles'])
+        merge_sites(tileji['sites'], tilejo['sites'])
 
-                process_type('pips')
-                process_type('wires')
     return tilejo
 
 
@@ -110,15 +135,11 @@ def check_corner_minmax(tilej, verbose=False):
     timfuz.tilej_stats(tilej)
 
 
-def check_corners_minmax(tilej, verbose=False):
-    # TODO: check fast vs slow
-    pass
-
-
 def run(fnins, fnout, verbose=False):
     tilejo = build_tilejo(fnins)
     check_corner_minmax(tilejo)
-    check_corners_minmax(tilejo)
+    # XXX: check fast vs slow?
+    # check_corners_minmax(tilejo)
     json.dump(
         tilejo,
         open(fnout, 'w'),
diff --git a/fuzzers/007-timing/timing_txt2csv.py b/fuzzers/007-timing/timing_txt2csv.py
deleted file mode 100644
index 0ba2b36d..00000000
--- a/fuzzers/007-timing/timing_txt2csv.py
+++ /dev/null
@@ -1,293 +0,0 @@
-#!/usr/bin/env python3
-
-from timfuz import Benchmark, A_di2ds
-import glob
-import math
-import json
-import sys
-from collections import OrderedDict
-
-# Speed index: some sort of special value
-SI_NONE = 0xFFFF
-
-# prefix to make easier to track
-# models do not overlap between PIPs and WIREs
-PREFIX_W = 'WIRE_'
-PREFIX_P = 'PIP_'
-
-
-def parse_pip(s):
-    # Entries like
-    # CLK_BUFG_REBUF_X60Y117/CLK_BUFG_REBUF.CLK_BUFG_REBUF_R_CK_GCLK0_BOT<<->>CLK_BUFG_REBUF_R_CK_GCLK0_TOP
-    # Convert to (site, type, pip_junction, pip)
-    pipstr, speed_index = s.split(':')
-    speed_index = int(speed_index)
-    site, instance = pipstr.split('/')
-    #type, pip_junction, pip = others.split('.')
-    #return (site, type, pip_junction, pip)
-    return site, instance, int(speed_index)
-
-
-def parse_node(s):
-    node, nwires = s.split(':')
-    return node, int(nwires)
-
-
-def parse_wire(s):
-    # CLBLM_R_X3Y80/CLBLM_M_D6:952
-    wirestr, speed_index = s.split(':')
-    site, instance = wirestr.split('/')
-    return site, instance, int(speed_index)
-
-
-# FIXME: these actually have a delay element
-# Probably need to put these back in
-def remove_virtual_pips(pips):
-    return pips
-    return filter(lambda pip: not re.match(r'CLBL[LM]_[LR]_', pip[0]), pips)
-
-
-def load_timing3(f, name='file'):
-    # src_bel dst_bel ico fast_max fast_min slow_max slow_min pips
-    f.readline()
-    ret = []
-    bads = 0
-    for l in f:
-        # FIXME: hack
-        if 0 and 'CLK' in l:
-            continue
-
-        l = l.strip()
-        if not l:
-            continue
-        parts = l.split(' ')
-        # FIXME: deal with these nodes
-        if len(parts) != 11:
-            bads += 1
-            continue
-        net, src_bel, dst_bel, ico, fast_max, fast_min, slow_max, slow_min, pips, nodes, wires = parts
-        pips = pips.split('|')
-        nodes = nodes.split('|')
-        wires = wires.split('|')
-        ret.append(
-            {
-                'net': net,
-                'src_bel': src_bel,
-                'dst_bel': dst_bel,
-                'ico': int(ico),
-                # ps
-                'fast_max': int(fast_max),
-                'fast_min': int(fast_min),
-                'slow_max': int(slow_max),
-                'slow_min': int(slow_min),
-                'pips': remove_virtual_pips([parse_pip(pip) for pip in pips]),
-                'nodes': [parse_node(node) for node in nodes],
-                'wires': [parse_wire(wire) for wire in wires],
-                'line': l,
-            })
-    print('  load %s: %d bad, %d good' % (name, bads, len(ret)))
-    #assert 0
-    return ret
-
-
-def load_speed_json(f):
-    j = json.load(f)
-    # Index speed indexes to names
-    speed_i2s = {}
-    for k, v in j['speed_model'].items():
-        i = v['speed_index']
-        if i != SI_NONE:
-            speed_i2s[i] = k
-    return j, speed_i2s
-
-
-# Verify the nodes and wires really do line up
-def vals2Adi_check(vals, names):
-    print('Checking')
-    for val in vals:
-        node_wires = 0
-        for _node, wiresn in val['nodes']:
-            node_wires += wiresn
-        assert node_wires == len(val['wires'])
-    print('Done')
-    assert 0
-
-
-def vals2Adi(vals, speed_i2s, name_tr={}, name_drop=[], verbose=False):
-    def pip2speed(pip):
-        _site, _name, speed_index = pip
-        return PREFIX_P + speed_i2s[speed_index]
-
-    def wire2speed(wire):
-        _site, _name, speed_index = wire
-        return PREFIX_W + speed_i2s[speed_index]
-
-    # Want this ordered
-    names = OrderedDict()
-
-    print(
-        'Creating matrix w/ tr: %d, drop: %d' % (len(name_tr), len(name_drop)))
-
-    # Take sites out entirely using handy "interconnect only" option
-    #vals = filter(lambda x: str(x).find('SLICE') >= 0, vals)
-    # Highest count while still getting valid result
-
-    # First index all of the given pip types
-    # Start out as set then convert to list to keep matrix order consistent
-    sys.stdout.write('Indexing delay elements ')
-    sys.stdout.flush()
-    progress = max(1, len(vals) / 100)
-    for vali, val in enumerate(vals):
-        if vali % progress == 0:
-            sys.stdout.write('.')
-            sys.stdout.flush()
-        odl = [(pip2speed(pip), None) for pip in val['pips']]
-        names.update(OrderedDict(odl))
-
-        odl = [(wire2speed(wire), None) for wire in val['wires']]
-        names.update(OrderedDict(odl))
-    print(' done')
-
-    # Apply transform
-    orig_names = len(names)
-    for k in (list(name_drop) + list(name_tr.keys())):
-        if k in names:
-            del names[k]
-        else:
-            print('WARNING: failed to remove %s' % k)
-    names.update(OrderedDict([(name, None) for name in name_tr.values()]))
-    print('Names tr %d => %d' % (orig_names, len(names)))
-
-    # Make unique list
-    names = list(names.keys())
-    name_s2i = {}
-    for namei, name in enumerate(names):
-        name_s2i[name] = namei
-    if verbose:
-        for name in names:
-            print('NAME: ', name)
-        for name in name_drop:
-            print('DROP: ', name)
-        for l, r in name_tr.items():
-            print('TR: %s => %s' % (l, r))
-
-    # Now create a matrix with all of these delays
-    # Each row needs len(names) elements
-    # -2 means 2 elements present, 0 means absent
-    # (could hit same pip twice)
-    print('Creating delay element matrix w/ %d names' % len(names))
-    Adi = [None for _i in range(len(vals))]
-    for vali, val in enumerate(vals):
-
-        def add_name(name):
-            if name in name_drop:
-                return
-            name = name_tr.get(name, name)
-            namei = name_s2i[name]
-            row_di[namei] = row_di.get(namei, 0) + 1
-
-        # Start with 0 occurances
-        #row = [0 for _i in range(len(names))]
-        row_di = {}
-
-        #print('pips: ', val['pips']
-        for pip in val['pips']:
-            add_name(pip2speed(pip))
-        for wire in val['wires']:
-            add_name(wire2speed(wire))
-        #A_ub.append(row)
-        Adi[vali] = row_di
-
-    return Adi, names
-
-
-# TODO: load directly as Ads
-# remove names_tr, names_drop
-def vals2Ads(vals, speed_i2s, verbose=False):
-    Adi, names = vals2Adi(vals, speed_i2s, verbose=False)
-    return A_di2ds(Adi, names)
-
-
-def load_Ads(speed_json_f, f_ins):
-
-    print('Loading data')
-
-    _speedj, speed_i2s = load_speed_json(speed_json_f)
-
-    vals = []
-    for avals in [load_timing3(f_in, name) for f_in, name in f_ins]:
-        vals.extend(avals)
-
-    Ads = vals2Ads(vals, speed_i2s)
-
-    def mkb(val):
-        return (
-            val['fast_max'], val['fast_min'], val['slow_max'], val['slow_min'])
-
-    b = [mkb(val) for val in vals]
-    ico = [val['ico'] for val in vals]
-
-    return Ads, b, ico
-
-
-def run(speed_json_f, fout, f_ins, verbose=0, corner=None):
-    Ads, bs, ico = load_Ads(speed_json_f, f_ins)
-
-    fout.write('ico,fast_max fast_min slow_max slow_min,rows...\n')
-    for row_bs, row_ds, row_ico in zip(bs, Ads, ico):
-        # like: 123 456 120 450, 1 a, 2 b
-        # first column has delay corners, followed by delay element count
-        items = [str(row_ico), ' '.join([str(x) for x in row_bs])]
-        for k, v in sorted(row_ds.items()):
-            items.append('%u %s' % (v, k))
-        fout.write(','.join(items) + '\n')
-
-
-def main():
-    import argparse
-
-    parser = argparse.ArgumentParser(
-        description=
-        'Convert obscure timing3.txt into more readable but roughly equivilent timing3.csv'
-    )
-
-    parser.add_argument('--verbose', type=int, help='')
-    # made a bulk conversion easier...keep?
-    parser.add_argument(
-        '--auto-name', action='store_true', help='timing3.txt => timing3.csv')
-    parser.add_argument(
-        '--speed-json',
-        default='build_speed/speed.json',
-        help='Provides speed index to name translation')
-    parser.add_argument('--out', default=None, help='Output timing3.csv file')
-    parser.add_argument('fns_in', nargs='+', help='Input timing3.txt files')
-    args = parser.parse_args()
-    bench = Benchmark()
-
-    fnout = args.out
-    if fnout is None:
-        if args.auto_name:
-            assert len(args.fns_in) == 1
-            fnin = args.fns_in[0]
-            fnout = fnin.replace('.txt', '.csv')
-            assert fnout != fnin, 'Expect .txt in'
-        else:
-            # practically there are too many stray prints to make this work as expected
-            assert 0, 'File name required'
-            fnout = '/dev/stdout'
-    print("Writing to %s" % fnout)
-    fout = open(fnout, 'w')
-
-    fns_in = args.fns_in
-    if not fns_in:
-        fns_in = glob.glob('specimen_*/timing3.txt')
-
-    run(
-        speed_json_f=open(args.speed_json, 'r'),
-        fout=fout,
-        f_ins=[(open(fn_in, 'r'), fn_in) for fn_in in fns_in],
-        verbose=args.verbose)
-
-
-if __name__ == '__main__':
-    main()
diff --git a/fuzzers/007-timing/timing_txt2icsv.py b/fuzzers/007-timing/timing_txt2icsv.py
new file mode 100644
index 00000000..469df204
--- /dev/null
+++ b/fuzzers/007-timing/timing_txt2icsv.py
@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+
+from timfuz import Benchmark, A_di2ds, PREFIX_W, PREFIX_P
+from timing_txt2json import gen_timing4n, load_speed_json
+
+import glob
+import math
+import json
+import sys
+from collections import OrderedDict
+
+
+# Verify the nodes and wires really do line up
+def vals2Adi_check(vals, names):
+    print('Checking')
+    for val in vals:
+        node_wires = 0
+        for _node, wiresn in val['nodes']:
+            node_wires += wiresn
+        assert node_wires == len(val['wires'])
+    print('Done')
+    assert 0
+
+
+def row_json2Ads(val, verbose=False):
+    '''Convert timing4 JSON into Ads interconnect equations'''
+
+    def pip2speed(pip):
+        _site, _name, pip_name = pip
+        return PREFIX_P + ':' + pip_name
+
+    def wire2speed(wire):
+        _site, _name, wire_name = wire
+        return PREFIX_W + ':' + wire_name
+
+    def add_name(name):
+        row_ds[name] = row_ds.get(name, 0) + 1
+
+    row_ds = {}
+
+    for pip in val['pips']:
+        add_name(pip2speed(pip))
+    for wire in val['wires']:
+        add_name(wire2speed(wire))
+    return row_ds
+
+
+def load_Ads_gen(speed_json_f, fn_ins):
+
+    print('Loading data')
+
+    _speedj, speed_i2s = load_speed_json(speed_json_f)
+
+    for fn_in in fn_ins:
+
+        def mkb(val):
+            t = val['t']
+            return (t['fast_max'], t['fast_min'], t['slow_max'], t['slow_min'])
+
+        for val in gen_timing4n(fn_in, speed_i2s):
+            row_ds = row_json2Ads(val)
+            row_bs = mkb(val)
+            row_ico = val['ico']
+
+            yield row_bs, row_ds, row_ico
+
+
+def run(speed_json_f, fout, fns_in, verbose=0, corner=None):
+    fout.write('ico,fast_max fast_min slow_max slow_min,rows...\n')
+    for row_bs, row_ds, row_ico in load_Ads_gen(speed_json_f, fns_in):
+        # XXX: consider removing ico column
+        # its obsolete at this point
+        if not row_ico:
+            continue
+        # like: 123 456 120 450, 1 a, 2 b
+        # first column has delay corners, followed by delay element count
+        items = [str(row_ico), ' '.join([str(x) for x in row_bs])]
+        for k, v in sorted(row_ds.items()):
+            items.append('%u %s' % (v, k))
+        fout.write(','.join(items) + '\n')
+
+
+def main():
+    import argparse
+
+    parser = argparse.ArgumentParser(
+        description=
+        'Convert obscure timing4.txt into timing4i.csv (interconnect delay variable occurances)'
+    )
+
+    parser.add_argument('--verbose', type=int, help='')
+    # made a bulk conversion easier...keep?
+    parser.add_argument(
+        '--auto-name', action='store_true', help='timing4.txt => timing4i.csv')
+    parser.add_argument(
+        '--speed-json',
+        default='build_speed/speed.json',
+        help='Provides speed index to name translation')
+    parser.add_argument('--out', default=None, help='Output timing4i.csv file')
+    parser.add_argument('fns_in', nargs='+', help='Input timing4.txt files')
+    args = parser.parse_args()
+    bench = Benchmark()
+
+    fnout = args.out
+    if fnout is None:
+        if args.auto_name:
+            assert len(args.fns_in) == 1
+            fnin = args.fns_in[0]
+            fnout = fnin.replace('.txt', 'i.csv')
+            assert fnout != fnin, 'Expect .txt in'
+        else:
+            # practically there are too many stray prints to make this work as expected
+            assert 0, 'File name required'
+            fnout = '/dev/stdout'
+    print("Writing to %s" % fnout)
+    fout = open(fnout, 'w')
+
+    fns_in = args.fns_in
+    if not fns_in:
+        fns_in = glob.glob('specimen_*/timing4.txt')
+
+    run(
+        speed_json_f=open(args.speed_json, 'r'),
+        fout=fout,
+        fns_in=fns_in,
+        verbose=args.verbose)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/fuzzers/007-timing/timing_txt2json.py b/fuzzers/007-timing/timing_txt2json.py
new file mode 100644
index 00000000..4d26a5f6
--- /dev/null
+++ b/fuzzers/007-timing/timing_txt2json.py
@@ -0,0 +1,201 @@
+#!/usr/bin/env python3
+
+from timfuz import Benchmark, A_di2ds
+import glob
+import math
+import json
+import sys
+from collections import OrderedDict
+
+# Speed index: some sort of special value
+SI_NONE = 0xFFFF
+
+
+def parse_pip(s, speed_i2s):
+    # Entries like
+    # CLK_BUFG_REBUF_X60Y117/CLK_BUFG_REBUF.CLK_BUFG_REBUF_R_CK_GCLK0_BOT<<->>CLK_BUFG_REBUF_R_CK_GCLK0_TOP
+    # Convert to (site, type, pip_junction, pip)
+    pipstr, speed_index = s.split(':')
+    speed_index = int(speed_index)
+    site, instance = pipstr.split('/')
+    #type, pip_junction, pip = others.split('.')
+    #return (site, type, pip_junction, pip)
+    return site, instance, speed_i2s[int(speed_index)]
+
+
+def parse_pips(pips, speed_i2s):
+    if not pips:
+        return []
+    return [parse_pip(pip, speed_i2s) for pip in pips.split('|')]
+
+
+def parse_wire(s, speed_i2s):
+    # CLBLM_R_X3Y80/CLBLM_M_D6:952
+    wirestr, speed_index = s.split(':')
+    site, instance = wirestr.split('/')
+    return site, instance, speed_i2s[int(speed_index)]
+
+
+def parse_wires(wires, speed_i2s):
+    if not wires:
+        return []
+    return [parse_wire(wire, speed_i2s) for wire in wires.split('|')]
+
+
+def gen_timing4(fn, speed_i2s):
+    f = open(fn, 'r')
+    header_want = "linetype,net,src_site,src_site_type,src_site_pin,src_bel,src_bel_pin,dst_site,dst_site_type,dst_site_pin,dst_bel,dst_bel_pin,ico,fast_max,fast_min,slow_max,slow_min,pips,wires"
+    ncols = len(header_want.split(','))
+
+    # src_bel dst_bel ico fast_max fast_min slow_max slow_min pips
+    header_got = f.readline().strip()
+    if header_got != header_want:
+        raise Exception("Unexpected columns")
+
+    rets = 0
+    # XXX: there were malformed lines, but think they are fixed now?
+    bads = 0
+    net_lines = 0
+    for l in f:
+
+        def group_line():
+            ncols = len('lintype,ico,delays'.split(','))
+            assert len(parts) == ncols
+            _lintype, ico, delays = parts
+            return int(ico), int(delays)
+
+        def net_line():
+            assert len(parts) == ncols, "Expected %u parts, got %u" % (
+                ncols, len(parts))
+            _lintype, net, src_site, src_site_type, src_site_pin, src_bel, src_bel_pin, dst_site, dst_site_type, dst_site_pin, dst_bel, dst_bel_pin, ico, fast_max, fast_min, slow_max, slow_min, pips, wires = parts
+
+            def filt_passthru_lut(bel_pins):
+                '''
+                Ex: SLICE_X11Y110/A6LUT/A6 SLICE_X11Y110/AFF/D
+                '''
+                parts = bel_pins.split()
+                if len(parts) == 1:
+                    return parts[0]
+                else:
+                    assert len(parts) == 2
+                    # the LUT shoudl always go first?
+                    bel_pin_lut, bel_pin_dst = parts
+                    assert '6LUT' in bel_pin_lut
+                    return bel_pin_dst
+
+            return {
+                'net': net,
+                'src': {
+                    'site': src_site,
+                    'site_type': src_site_type,
+                    'site_pin': src_site_pin,
+                    'bel': src_bel,
+                    'bel_pin': src_bel_pin,
+                },
+                'dst': {
+                    'site': dst_site,
+                    'site_type': dst_site_type,
+                    'site_pin': dst_site_pin,
+                    'bel': dst_bel,
+                    'bel_pin': filt_passthru_lut(dst_bel_pin),
+                },
+                't': {
+                    # ps
+                    'fast_max': int(fast_max),
+                    'fast_min': int(fast_min),
+                    'slow_max': int(slow_max),
+                    'slow_min': int(slow_min),
+                },
+                'ico': int(ico),
+                'pips': parse_pips(pips, speed_i2s),
+                'wires': parse_wires(wires, speed_i2s),
+                'line': l,
+            }
+
+        l = l.strip()
+        if not l:
+            continue
+        parts = l.split(',')
+        lintype = parts[0]
+
+        val = {
+            'NET': net_line,
+            'GROUP': group_line,
+        }[lintype]()
+        yield lintype, val
+
+        rets += 1
+    print('  load %s: %d bad, %d good lines' % (fn, bads, rets))
+
+
+def gen_timing4n(fn, speed_i2s):
+    '''Only generate nets'''
+    for lintype, val in gen_timing4(fn, speed_i2s):
+        if lintype == 'NET':
+            yield val
+
+
+def gen_timing4a(fn, speed_i2s):
+    '''
+    Like above, but aggregate ico + non-ico into single entries
+    Key these based on uniqueness of (src_bel, dst_bel)
+
+    ico 0 is followed by 1
+    They should probably even be in the same order
+    Maybe just assert that?
+    '''
+    entries = {}
+    timgen = gen_timing4(fn, speed_i2s)
+    rets = 0
+    while True:
+
+        def get_ico(exp_ico):
+            ret = []
+            try:
+                lintype, val = next(timgen)
+            except StopIteration:
+                return None
+            assert lintype == 'GROUP'
+            ico, delays = val
+            assert ico == exp_ico
+            for _ in range(delays):
+                lintype, val = next(timgen)
+                assert lintype == 'NET'
+                ret.append(val)
+            return ret
+
+        ico0s = get_ico(0)
+        if ico0s is None:
+            break
+        ico1s = get_ico(1)
+        # TODO: verify this is actually true
+        assert len(ico0s) == len(ico1s)
+
+        def same_path(l, r):
+            # if source and dest are the same, should be the same thing
+            return l['src']['bel_pin'] == r['src']['bel_pin'] and l['dst'][
+                'bel_pin'] == r['dst']['bel_pin']
+
+        for ico0, ico1 in zip(ico0s, ico1s):
+            # TODO: verify this is actually true
+            # otherwise move to more complex algorithm
+            assert same_path(ico0, ico1)
+            # aggregate timing info as (ic0, ic1) into ico0
+            ico0['t'] = (
+                ico0['t'],
+                ico1['t'],
+            )
+            yield ico0
+            rets += 1
+    print('  load %s: %u aggregated lines' % (fn, rets))
+
+
+def load_speed_json(f):
+    j = json.load(f)
+    # Index speed indexes to names
+    speed_i2s = {}
+    for k, v in j['speed_model'].items():
+        i = v['speed_index']
+        if i != SI_NONE:
+            speed_i2s[i] = k
+    return j, speed_i2s
diff --git a/fuzzers/007-timing/timing_txt2scsv.py b/fuzzers/007-timing/timing_txt2scsv.py
new file mode 100644
index 00000000..1dedb470
--- /dev/null
+++ b/fuzzers/007-timing/timing_txt2scsv.py
@@ -0,0 +1,167 @@
+#!/usr/bin/env python3
+
+from timfuz import Benchmark, A_di2ds, sw_ei_vals2s, sw_eo_vals2s, sw_i_vals2s
+from timing_txt2json import gen_timing4a, load_speed_json
+
+import glob
+import math
+import json
+import sys
+from collections import OrderedDict
+
+
+def gen_diffs(speed_json_f, fns_in):
+    print('Loading data')
+    _speedj, speed_i2s = load_speed_json(speed_json_f)
+
+    for fn_in in fns_in:
+        for val in gen_timing4a(fn_in, speed_i2s):
+            # diff to get site only delay
+            tsites = {}
+            for k in val['t'][0].keys():
+                v = val['t'][0][k] - val['t'][1][k]
+                assert v >= 0
+                tsites[k] = v
+            yield val, tsites
+
+
+# XXX: move to json converter?
+def sd_parts(sd):
+    '''Return site_type, site_pin, bel_type, bel_pin as non-prefixed strings'''
+    # IOB_X0Y106 IOB_X0Y106/INBUF_EN IOB_X0Y106/INBUF_EN/OUT
+    # print(sd['site'], sd['bel'], sd['bel_pin'])
+    site_type = sd['site_type']
+    site, bel_type, bel_pin = sd['bel_pin'].split('/')
+    assert sd['site'] == site
+    assert sd['bel'] == site + '/' + bel_type
+
+    site_pin_str = sd['site_pin']
+    if site_pin_str:
+        site, site_pin = sd['site_pin'].split('/')
+        assert sd['site_pin'] == sd['site'] + '/' + site_pin
+    else:
+        site_pin = None
+    return site_type, site_pin, bel_type, bel_pin
+
+
+def run(speed_json_f, fout, fns_in, verbose=0, corner=None):
+    '''
+    instead of writing to a simplified csv, lets just go directly to a delay format identical to what fabric uses
+    Path types:
+    -inter site: think these are removed for now?
+        1 model
+        NOTE: be careful of a net that goes external and comes back in, which isn't inter site
+        definition is that it doesn't have any site pins
+    -intra site
+        2 models
+    '''
+
+    fout.write(
+        'ico,fast_max fast_min slow_max slow_min,src_site_type,src_site,src_bel,src_bel_pin,dst_site_type,dst_site,dst_bel,dst_bel_pin\n'
+    )
+    for val, tsites in gen_diffs(speed_json_f, fns_in):
+
+        def mkb(t):
+            return (t['fast_max'], t['fast_min'], t['slow_max'], t['slow_min'])
+
+        bstr = ' '.join([str(x) for x in mkb(tsites)])
+
+        # Identify inter site transaction (SITEI)
+        if not val['src']['site_pin'] and not val['dst']['site_pin']:
+            # add one delay model for the path
+            # XXX: can these be solved exactly?
+            # might still have fanout and such
+
+            src_site_type, _src_site_pin, src_bel_type, src_bel_pin = sd_parts(
+                val['src'])
+            dst_site_type, _dst_site_pin, dst_bel_type, dst_bel_pin = sd_parts(
+                val['dst'])
+            assert src_site_type == dst_site_type
+            assert (src_bel_type, src_bel_pin) != (dst_bel_type, dst_bel_pin)
+
+            k = sw_i_vals2s(
+                src_site_type, src_bel_type, src_bel_pin, dst_bel_type,
+                dst_bel_pin)
+            row_ds = {k: 1}
+        elif val['src']['site_pin'] and val['dst']['site_pin']:
+            # if it exits a site it should enter another (possibly the same site)
+            # site in (SITEI) or site out (SITEO)?
+            # nah, keep things simple and just call them SITEW
+            row_ds = {}
+
+            def add_dst_delay():
+                sd = val['dst']
+                site_type, src_site_pin, dst_bel, dst_bel_pin = sd_parts(sd)
+                k = sw_ei_vals2s(site_type, src_site_pin, dst_bel, dst_bel_pin)
+                assert k not in row_ds
+                row_ds[k] = 1
+
+            def add_src_delay():
+                sd = val['src']
+                site_type, dst_site_pin, src_bel, src_bel_pin = sd_parts(sd)
+                k = sw_eo_vals2s(site_type, src_bel, src_bel_pin, dst_site_pin)
+                assert k not in row_ds
+                row_ds[k] = 1
+
+            add_dst_delay()
+            add_src_delay()
+        else:
+            # dropped by the tcl script
+            raise Exception("FIXME: handle destination but no source")
+
+        row_ico = 0
+        items = [str(row_ico), bstr]
+        for k, v in sorted(row_ds.items()):
+            items.append('%u %s' % (v, k))
+        fout.write(','.join(items) + '\n')
+    print('done')
+
+
+def main():
+    import argparse
+
+    parser = argparse.ArgumentParser(
+        description=
+        'Convert obscure timing4.txt into timing4s.csv (site delay variable occurances)'
+    )
+
+    parser.add_argument('--verbose', type=int, help='')
+    # made a bulk conversion easier...keep?
+    parser.add_argument(
+        '--auto-name', action='store_true', help='timing4.txt => timing4i.csv')
+    parser.add_argument(
+        '--speed-json',
+        default='build_speed/speed.json',
+        help='Provides speed index to name translation')
+    parser.add_argument('--out', default=None, help='Output timing4i.csv file')
+    parser.add_argument('fns_in', nargs='+', help='Input timing4.txt files')
+    args = parser.parse_args()
+    bench = Benchmark()
+
+    fnout = args.out
+    if fnout is None:
+        if args.auto_name:
+            assert len(args.fns_in) == 1
+            fnin = args.fns_in[0]
+            fnout = fnin.replace('.txt', 's.csv')
+            assert fnout != fnin, 'Expect .txt in'
+        else:
+            # practically there are too many stray prints to make this work as expected
+            assert 0, 'File name required'
+            fnout = '/dev/stdout'
+    print("Writing to %s" % fnout)
+    fout = open(fnout, 'w')
+
+    fns_in = args.fns_in
+    if not fns_in:
+        fns_in = glob.glob('specimen_*/timing4.txt')
+
+    run(
+        speed_json_f=open(args.speed_json, 'r'),
+        fout=fout,
+        fns_in=fns_in,
+        verbose=args.verbose)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/utils/genheader.sh b/utils/genheader.sh
index 7c9bba0f..71766634 100644
--- a/utils/genheader.sh
+++ b/utils/genheader.sh
@@ -7,8 +7,9 @@ fi
 
 set -ex
 
-test $# = 1
-test ! -e $1
-mkdir $1
-cd $1
+# for some reason on sourced script set -e doesn't work
+test $# = 1 || exit 1
+test ! -e "$1"
+mkdir "$1"
+cd "$1"