diff --git a/nodist/invoke_atsim b/nodist/invoke_atsim
new file mode 100755
index 000000000..3abcdced9
--- /dev/null
+++ b/nodist/invoke_atsim
@@ -0,0 +1,59 @@
+#!/usr/bin/perl -w
+# See copyright, etc in below POD section.
+######################################################################
+
+require 5.006_001;
+use strict;
+
+#======================================================================
+# main
+
+delete $ENV{MODULE_VERSION};
+_setup_modules();
+module('add','axiom-athdl');
+exec('atsim',@ARGV);
+
+#######################################################################
+# Modules package
+
+sub _setup_modules {
+    # Load the 'module' command into the environment
+    my $init = "$ENV{MODULESHOME}/init/perl";
+    (-f $init) or die "%Error: Script not found: $init,";
+    require $init;
+}
+
+#######################################################################
+__END__
+
+=pod
+
+=head1 NAME
+
+invoke_atsim - Invoke tool under "modules" command
+
+=head1 SYNOPSIS
+
+  invoke_atsim  {ncv arguments}
+
+=head1 DESCRIPTION
+
+=head1 DISTRIBUTION
+
+Copyright 2005-2010 by Wilson Snyder.  This package is free software; you
+can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
+
+=head1 AUTHORS
+
+Wilson Snyder <wsnyder@wsnyder.org>
+
+=head1 SEE ALSO
+
+=cut
+
+######################################################################
+### Local Variables:
+### compile-command: "./invoke_atsim -help"
+### End:
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index 08783dbed..c307817ec 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -40,6 +40,7 @@ our @Orig_ARGV = @ARGV;
 our @Orig_ARGV_Sw;  foreach (@Orig_ARGV) { push @Orig_ARGV_Sw, $_ if /^-/ && !/^-j/; }
 
 $Debug = 0;
+my $opt_atsim;
 my $opt_benchmark;
 my @opt_tests;
 my $opt_gdb;
@@ -61,6 +62,7 @@ Getopt::Long::config ("pass_through");
 if (! GetOptions (
 		  "benchmark:i" => sub { $opt_benchmark = $_[1] ? $_[1] : 1; },
 		  "debug"	=> \&debug,
+		  "atsim|athdl!"=> \$opt_atsim,
 		  "gdb!"	=> \$opt_gdb,
 		  "gdbbt!"	=> \$opt_gdbbt,
 		  "gdbsim!"	=> \$opt_gdbsim,
@@ -86,7 +88,7 @@ $opt_jobs = calc_jobs() if defined $opt_jobs && $opt_jobs==0;
 
 $Fork->max_proc($opt_jobs);
 
-if (!$opt_iv && !$opt_vcs && !$opt_nc && !$opt_vlt) {
+if (!$opt_atsim && !$opt_iv && !$opt_vcs && !$opt_nc && !$opt_vlt) {
     $opt_vlt = 1;
 }
 
@@ -101,6 +103,7 @@ my $leftcnt=0; my $okcnt=0; my $failcnt=0; my $skcnt=0;
 my @fails;
 
 foreach my $testpl (@opt_tests) {
+    one_test(pl_filename => $testpl, atsim=>1) if $opt_atsim;
     one_test(pl_filename => $testpl, iv=>1) if $opt_iv;
     one_test(pl_filename => $testpl, nc=>1) if $opt_nc;
     one_test(pl_filename => $testpl, vcs=>1) if $opt_vcs;
@@ -261,6 +264,12 @@ sub new {
 	v_flags2 => [],  # Overridden in some sim files
 	v_other_filenames => [],	# After the filename so we can spec multiple files
 	all_run_flags => [],
+        # ATSIM
+	atsim => 0,
+	atsim_flags => [split(/\s+/,"-c +sv +define+atsim"),
+			"+sv_dir+$self->{obj_dir}/.athdl_compile"],
+	atsim_flags2 => [],  # Overridden in some sim files
+	atsimrun_flags => [],
         # IV
 	iv => 0,
 	iv_flags => [split(/\s+/,"+define+iverilog -o $self->{obj_dir}/simiv")],
@@ -288,6 +297,7 @@ sub new {
 	%$self};
     bless $self, $class;
 
+    $self->{mode} ||= "atsim" if $self->{atsim};
     $self->{mode} ||= "vcs" if $self->{vcs};
     $self->{mode} ||= "vlt" if $self->{vlt};
     $self->{mode} ||= "nc" if $self->{nc};
@@ -387,6 +397,20 @@ sub compile {
     $self->{trace} = 1 if ($opt_trace || $checkflags =~ /-trace\b/);
     $self->{coverage} = 1 if ($checkflags =~ /-coverage\b/);
 
+    if ($param{atsim}) {
+	$self->_make_top();
+	$self->_run(logfile=>"$self->{obj_dir}/atsim_compile.log",
+		    fails=>$param{fails},
+		    cmd=>[($ENV{VERILATOR_ATSIM}||"atsim"),
+			  @{$param{atsim_flags}},
+			  @{$param{atsim_flags2}},
+			  @{$param{v_flags}},
+			  @{$param{v_flags2}},
+			  $param{top_filename},
+			  $param{top_shell_filename},
+			  @{$param{v_other_filenames}},
+			  ]);
+    }
     if ($param{vcs}) {
 	$self->_make_top();
 	$self->_run(logfile=>"$self->{obj_dir}/vcs_compile.log",
@@ -511,6 +535,14 @@ sub execute {
     my $run_env = $param{run_env};
     $run_env .= ' ' if $run_env;
 
+    if ($param{atsim}) {
+	$self->_run(logfile=>"$self->{obj_dir}/atsim_sim.log",
+		    fails=>$param{fails},
+		    cmd=>["echo q | ".$run_env."$self->{obj_dir}/athdl_sv",
+			  @{$param{atsimrun_flags}},
+			  @{$param{all_run_flags}},
+			  ]);
+    }
     if ($param{iv}) {
 	$self->_run(logfile=>"$self->{obj_dir}/iv_sim.log",
 		    fails=>$param{fails},
@@ -522,7 +554,7 @@ sub execute {
     if ($param{nc}) {
 	$self->_run(logfile=>"$self->{obj_dir}/nc_sim.log",
 		    fails=>$param{fails},
-		    cmd=>[$run_env.($ENV{VERILATOR_NCVERILOG}||"ncverilog"),
+		    cmd=>["echo q | ".$run_env.($ENV{VERILATOR_NCVERILOG}||"ncverilog"),
 			  @{$param{ncrun_flags}},
 			  @{$param{all_run_flags}},
 			  ]);
@@ -531,7 +563,7 @@ sub execute {
 	#my $fh = IO::File->new(">simv.key") or die "%Error: $! simv.key,";
 	#$fh->print("quit\n"); $fh->close;
 	$self->_run(logfile=>"$self->{obj_dir}/vcs_sim.log",
-		    cmd=>[$run_env."./simv",
+		    cmd=>["echo q | ".$run_env."./simv",
 			  @{$param{all_run_flags}},
 		          ],
 		    %param,
@@ -1166,6 +1198,10 @@ driver.pl invokes Verilator or another simulator on each little test file.
 
 =over 4
 
+=item --atsim
+
+Run using ATSIM.
+
 =item --benchmark [<cycles>]
 
 Show execution times of each step.  If an optional number is given,
diff --git a/test_regress/t/t_alw_split.pl b/test_regress/t/t_alw_split.pl
index 7df4b44de..d26471e64 100755
--- a/test_regress/t/t_alw_split.pl
+++ b/test_regress/t/t_alw_split.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ["--stats"],
+	 verilator_flags2 => ["--stats"],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_alw_splitord.pl b/test_regress/t/t_alw_splitord.pl
index 224435f0c..28664c281 100755
--- a/test_regress/t/t_alw_splitord.pl
+++ b/test_regress/t/t_alw_splitord.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ["--stats"],
+	 verilator_flags2 => ["--stats"],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_assert_basic_fail.pl b/test_regress/t/t_assert_basic_fail.pl
index 762b010e1..7f32d9b12 100755
--- a/test_regress/t/t_assert_basic_fail.pl
+++ b/test_regress/t/t_assert_basic_fail.pl
@@ -16,7 +16,7 @@ compile (
 	 );
 
 execute (
-	 fails => 1,
+	 fails => $Self->{vlt},
 	 );
 
 ok(1);
diff --git a/test_regress/t/t_assert_synth_full.pl b/test_regress/t/t_assert_synth_full.pl
index 308f0aa32..3fcf338c9 100755
--- a/test_regress/t/t_assert_synth_full.pl
+++ b/test_regress/t/t_assert_synth_full.pl
@@ -16,7 +16,7 @@ compile (
 
 execute (
 	 check_finished=>0,
-	 fails=>1,
+	 fails=> $Self->{vlt},
 	 expect=>
 '%Error: t_assert_synth.v:\d+: Assertion failed in top.v: synthesis full_case'
 	 );
diff --git a/test_regress/t/t_assert_synth_parallel.pl b/test_regress/t/t_assert_synth_parallel.pl
index 762a3dc9e..19f0646c1 100755
--- a/test_regress/t/t_assert_synth_parallel.pl
+++ b/test_regress/t/t_assert_synth_parallel.pl
@@ -16,7 +16,7 @@ compile (
 
 execute (
 	 check_finished=>0,
-	 fails=>1,
+	 fails => $Self->{v3},
 	 expect=>
 '%Error: t_assert_synth.v:\d+: Assertion failed in top.v: synthesis parallel_case'
 	 );
diff --git a/test_regress/t/t_case_write1.pl b/test_regress/t/t_case_write1.pl
index 8ff03e216..b0a0163c6 100755
--- a/test_regress/t/t_case_write1.pl
+++ b/test_regress/t/t_case_write1.pl
@@ -10,7 +10,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 $Self->{golden_out} ||= "t/$Self->{name}.out";
 
 compile (
-	 v_flags2 => [$Self->{v3}?"--stats --O3 -x-assign fast":""],
+	 verilator_flags2 => ["--stats --O3 -x-assign fast"],
 	 );
 
 execute (
diff --git a/test_regress/t/t_case_write2.pl b/test_regress/t/t_case_write2.pl
index f19e4f4e5..0d5c0beb2 100755
--- a/test_regress/t/t_case_write2.pl
+++ b/test_regress/t/t_case_write2.pl
@@ -10,7 +10,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 $Self->{golden_out} ||= "t/$Self->{name}.out";
 
 compile (
-	 v_flags2 => [$Self->{v3}?"--stats --O3 -x-assign fast":""],
+	 verilator_flags2 => ["--stats --O3 -x-assign fast"],
 	 );
 
 execute (
diff --git a/test_regress/t/t_case_x.pl b/test_regress/t/t_case_x.pl
index 4d32d3bd4..bbefb98ca 100755
--- a/test_regress/t/t_case_x.pl
+++ b/test_regress/t/t_case_x.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ["--x-assign 0"],
+	 verilator_flags2 => ["--x-assign 0"],
 	 );
 
 execute (
diff --git a/test_regress/t/t_clk_gater.pl b/test_regress/t/t_clk_gater.pl
index e06e83042..4dc82a1a0 100755
--- a/test_regress/t/t_clk_gater.pl
+++ b/test_regress/t/t_clk_gater.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-    v_flags2 => ["--stats"],
+    verilator_flags2 => ["--stats"],
     );
 
 execute (
diff --git a/test_regress/t/t_cover_line.pl b/test_regress/t/t_cover_line.pl
index 70958a9aa..14d2fe474 100755
--- a/test_regress/t/t_cover_line.pl
+++ b/test_regress/t/t_cover_line.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 verilator_flags2 => [$Self->{v3}?'--sp --coverage-line':''],
+	 verilator_flags2 => ['--sp --coverage-line'],
 	 );
 
 execute (
diff --git a/test_regress/t/t_cover_line.v b/test_regress/t/t_cover_line.v
index 4a57dff9c..65c8d521a 100644
--- a/test_regress/t/t_cover_line.v
+++ b/test_regress/t/t_cover_line.v
@@ -48,7 +48,11 @@ module t (/*AUTOARG*/
 	    toggle <= '1;
 	 end
 	 else if (cyc==5) begin
+`ifdef VERILATOR
 	    $c("call_task();");
+`else
+	    call_task();
+`endif
 	 end
 	 else if (cyc==10) begin
 	    $write("*-* All Finished *-*\n");
diff --git a/test_regress/t/t_cover_sva_notflat.pl b/test_regress/t/t_cover_sva_notflat.pl
index b398e38ad..5d55d601e 100755
--- a/test_regress/t/t_cover_sva_notflat.pl
+++ b/test_regress/t/t_cover_sva_notflat.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => [$Self->{v3}?'--assert --sp --coverage-user':''],
+	 verilator_flags2 => ['--assert --sp --coverage-user'],
 	 );
 
 execute (
@@ -20,7 +20,8 @@ execute (
 # Allow old Perl format dump, or new binary dump
 # Check that the hierarchy doesn't include __PVT__
 # Otherwise our coverage reports would look really ugly
-file_grep ($Self->{coverage_filename}, qr/(top\.v\.sub.*.cyc_eq_5)/);
+file_grep ($Self->{coverage_filename}, qr/(top\.v\.sub.*.cyc_eq_5)/)
+    if $Self->{vlt};
 
 ok(1);
 1;
diff --git a/test_regress/t/t_cover_toggle.pl b/test_regress/t/t_cover_toggle.pl
index 3478b4472..23acfc141 100755
--- a/test_regress/t/t_cover_toggle.pl
+++ b/test_regress/t/t_cover_toggle.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 verilator_flags2 => [$Self->{v3}?'--sp --coverage-toggle --stats':''],
+	 verilator_flags2 => ['--sp --coverage-toggle --stats'],
 	 );
 
 execute (
@@ -18,7 +18,8 @@ execute (
 # Read the input .v file and do any CHECK_COVER requests
 inline_checks();
 
-file_grep ($Self->{stats}, qr/Coverage, Toggle points joined\s+25/i);
+file_grep ($Self->{stats}, qr/Coverage, Toggle points joined\s+25/i)
+    if $Self->{vlt};
 
 ok(1);
 1;
diff --git a/test_regress/t/t_flag_ldflags.pl b/test_regress/t/t_flag_ldflags.pl
index 4d9800a49..2a52f5bcd 100755
--- a/test_regress/t/t_flag_ldflags.pl
+++ b/test_regress/t/t_flag_ldflags.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 $Self->_run (cmd=>["cd $Self->{obj_dir}"
 		   ." && g++ -c ../../t/t_flag_ldflags_a.cpp"
 		   ." && ar r t_flag_ldflags_a.a t_flag_ldflags_a.o"
diff --git a/test_regress/t/t_func_check.v b/test_regress/t/t_func_check.v
index 943e79820..32e391d15 100644
--- a/test_regress/t/t_func_check.v
+++ b/test_regress/t/t_func_check.v
@@ -12,7 +12,7 @@ module t (
 
    chk chk (.clk	(clk),
 	    .rst_l	(1'b1),
-	    .expr	(|crc),
+	    .expr	(|crc)
 	    );
 
    always @ (posedge clk) begin
diff --git a/test_regress/t/t_func_first.v b/test_regress/t/t_func_first.v
index 16841e680..1ee1f80b8 100644
--- a/test_regress/t/t_func_first.v
+++ b/test_regress/t/t_func_first.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_task (/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_func_graphcirc.v b/test_regress/t/t_func_graphcirc.v
index 8773c24a3..bc28e5b17 100644
--- a/test_regress/t/t_func_graphcirc.v
+++ b/test_regress/t/t_func_graphcirc.v
@@ -37,10 +37,14 @@ module t (clk);
             if ( cyc >= 4 ) begin
 	       dindex = dindex + 2; //*** Error line
 	       $display("%m: DIndex increment %d", cyc);
+`ifdef VERILATOR
 	       $c("VL_PRINTF(\"Hello1?\\n\");");
+`endif
             end
+`ifdef VERILATOR
 	    $c("VL_PRINTF(\"Hello2?\\n\");");
 	    $c("VL_PRINTF(\"Hello3?\\n\");");
+`endif
 	 end
       end
    endtask
diff --git a/test_regress/t/t_func_grey.v b/test_regress/t/t_func_grey.v
index cebdffc0f..fac134607 100644
--- a/test_regress/t/t_func_grey.v
+++ b/test_regress/t/t_func_grey.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_func (/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_func_lib_sub.pl b/test_regress/t/t_func_lib_sub.pl
index d5af9027a..79580b4a7 100755
--- a/test_regress/t/t_func_lib_sub.pl
+++ b/test_regress/t/t_func_lib_sub.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 compile (
 	 );
 # No execute
diff --git a/test_regress/t/t_func_public_trace.pl b/test_regress/t/t_func_public_trace.pl
index bcc777159..bc1d49232 100755
--- a/test_regress/t/t_func_public_trace.pl
+++ b/test_regress/t/t_func_public_trace.pl
@@ -12,7 +12,7 @@ my $pubtask = ($Self->{v3} && verilator_version() =~ /\(public_tasks\)/);  # TBD
 top_filename("t/t_func_public.v");
 
 compile (
-	 v_flags2 => [($pubtask?'-DVERILATOR_PUBLIC_TASKS':''), "--trace"],
+	 verilator_flags2 => [($pubtask?'-DVERILATOR_PUBLIC_TASKS':''), "--trace"],
 	 fails => $fail,
 	 );
 
diff --git a/test_regress/t/t_help.pl b/test_regress/t/t_help.pl
index c646f70b1..ba73b7641 100755
--- a/test_regress/t/t_help.pl
+++ b/test_regress/t/t_help.pl
@@ -7,12 +7,14 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 $Self->_run(fails=>1,
 		 cmd=>["perl","../bin/verilator",
 		       "--help"],
 		 logfile=>"$Self->{obj_dir}/t_help.log",
 		 tee=>0,
-		 ) if $Self->{v3};
+	    );
 
 file_grep ("$Self->{obj_dir}/t_help.log", qr/DISTRIBUTION/i);
 
diff --git a/test_regress/t/t_initial.v b/test_regress/t/t_initial.v
index 7cb6d14b8..0749fbdbf 100644
--- a/test_regress/t/t_initial.v
+++ b/test_regress/t/t_initial.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_initial (/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_inst_tree_inl0_pub1.pl b/test_regress/t/t_inst_tree_inl0_pub1.pl
index d0ed70613..8bfe8677b 100755
--- a/test_regress/t/t_inst_tree_inl0_pub1.pl
+++ b/test_regress/t/t_inst_tree_inl0_pub1.pl
@@ -10,7 +10,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 top_filename("t/t_inst_tree.v");
 
 compile (
-	 v_flags2 => ['+define+NOUSE_INLINE', '+define+USE_PUBLIC', '--stats'],
+	 verilator_flags2 => ['+define+NOUSE_INLINE', '+define+USE_PUBLIC', '--stats'],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_inst_wideconst.pl b/test_regress/t/t_inst_wideconst.pl
index 96d6aa1b1..fb2c8172c 100755
--- a/test_regress/t/t_inst_wideconst.pl
+++ b/test_regress/t/t_inst_wideconst.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ['-public'],
+	 verilator_flags2 => ['-public'],
 	 );
 
 execute (
diff --git a/test_regress/t/t_lint_implicit_port.pl b/test_regress/t/t_lint_implicit_port.pl
index 4dfa9b44a..bd5d46c3e 100755
--- a/test_regress/t/t_lint_implicit_port.pl
+++ b/test_regress/t/t_lint_implicit_port.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 compile (
 	 v_flags => ["-Wno-IMPLICIT"],
 	 );
diff --git a/test_regress/t/t_math_arith.v b/test_regress/t/t_math_arith.v
index f54a9c2ef..a001cdafc 100644
--- a/test_regress/t/t_math_arith.v
+++ b/test_regress/t/t_math_arith.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_arith(/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_math_imm2.pl b/test_regress/t/t_math_imm2.pl
index aef545263..c151ce6a6 100755
--- a/test_regress/t/t_math_imm2.pl
+++ b/test_regress/t/t_math_imm2.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->skip("Verilator only test") if !$Self->{vlt};
+
 compile (
 	 make_top_shell => 0,
 	 make_main => 0,
diff --git a/test_regress/t/t_mem_fifo.v b/test_regress/t/t_mem_fifo.v
index a84389d04..df378260d 100644
--- a/test_regress/t/t_mem_fifo.v
+++ b/test_regress/t/t_mem_fifo.v
@@ -90,7 +90,6 @@ module fifo (/*AUTOARG*/
    // verilator lint_off VARHIDDEN
    reg [65:0] 	 fifo[0:fifoDepth-1];
    // verilator lint_on VARHIDDEN
-   reg [`PTRBITSM1:0] wrPtr, rdPtr;
 
    //reg [65:0] 	      temp;
 
diff --git a/test_regress/t/t_mem_first.v b/test_regress/t/t_mem_first.v
index 2a7685ef9..de95f7f1c 100644
--- a/test_regress/t/t_mem_first.v
+++ b/test_regress/t/t_mem_first.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_mem (/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_mem_shift.pl b/test_regress/t/t_mem_shift.pl
index e3cdd650b..6be6d65d5 100755
--- a/test_regress/t/t_mem_shift.pl
+++ b/test_regress/t/t_mem_shift.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ["--stats"],
+	 verilator_flags2 => ["--stats"],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_mod_dup_bad.pl b/test_regress/t/t_mod_dup_bad.pl
index de99944e2..c08302fbc 100755
--- a/test_regress/t/t_mod_dup_bad.pl
+++ b/test_regress/t/t_mod_dup_bad.pl
@@ -7,15 +7,16 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->skip("Verilator only test") if !$Self->{vlt};
+
 compile (
-	 fails=>$Self->{v3},
-	 nc=>0,  # Need to get it not to give the prompt
+	 fails=>1,
 	 expect=>
 '%Error-MODDUP: t/t_mod_dup_bad.v:\d+: Duplicate declaration of module: a
 %Error-MODDUP: t/t_mod_dup_bad.v:\d+: ... Location of original declaration
 .*
 %Error: Exiting due to.*',
-	 ) if $Self->{v3};
+	 );
 
 ok(1);
 1;
diff --git a/test_regress/t/t_mod_dup_ign.pl b/test_regress/t/t_mod_dup_ign.pl
index acfee1103..09e214c4a 100755
--- a/test_regress/t/t_mod_dup_ign.pl
+++ b/test_regress/t/t_mod_dup_ign.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->skip("Verilator only test") if !$Self->{vlt};
+
 compile (
 	 make_top_shell => 0,
 	 make_main => 0,
diff --git a/test_regress/t/t_preproc_kwd.v b/test_regress/t/t_preproc_kwd.v
index 412767d61..853e8a5b2 100644
--- a/test_regress/t/t_preproc_kwd.v
+++ b/test_regress/t/t_preproc_kwd.v
@@ -9,25 +9,45 @@ module t (/*AUTOARG*/
    );
    input clk;
 
-`begin_keywords "1364-1995"
-  integer signed; initial signed = 1;
-`end_keywords
-`begin_keywords "1364-2001"
-  integer bit; initial bit = 1;
-`end_keywords
-`begin_keywords "1364-2005"
-  integer final; initial final = 1;
-`end_keywords
-`begin_keywords "1800-2005"
-  integer global; initial global = 1;
- `begin_keywords "1800-2009"
-  final begin
-     $write("*-* All Finished *-*\n");
-  end
- `end_keywords
-`end_keywords
+   s1 s1 ();
+   s2 s2 ();
+   s3 s3 ();
+   s4 s4 ();
+   s5 s5 ();
 
    initial begin
       $finish;
    end
 endmodule
+
+`begin_keywords "1364-1995"
+module s1;
+  integer signed; initial signed = 1;
+endmodule
+`end_keywords
+
+`begin_keywords "1364-2001"
+module s2;
+  integer bit; initial bit = 1;
+endmodule
+`end_keywords
+
+`begin_keywords "1364-2005"
+module s3;
+  integer final; initial final = 1;
+endmodule
+`end_keywords
+
+`begin_keywords "1800-2005"
+module s4;
+  integer global; initial global = 1;
+endmodule
+`end_keywords
+
+`begin_keywords "1800-2009"
+module s5;
+ final begin
+    $write("*-* All Finished *-*\n");
+ end
+endmodule
+`end_keywords
diff --git a/test_regress/t/t_rnd.v b/test_regress/t/t_rnd.v
index 18629bb9f..c080df8a3 100644
--- a/test_regress/t/t_rnd.v
+++ b/test_regress/t/t_rnd.v
@@ -3,7 +3,7 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2003 by Wilson Snyder.
 
-module t_rnd(/*AUTOARG*/
+module t (/*AUTOARG*/
    // Inputs
    clk
    );
diff --git a/test_regress/t/t_unopt_combo_isolate.pl b/test_regress/t/t_unopt_combo_isolate.pl
index c4b2d2ad6..814e80865 100755
--- a/test_regress/t/t_unopt_combo_isolate.pl
+++ b/test_regress/t/t_unopt_combo_isolate.pl
@@ -10,7 +10,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 top_filename("t/t_unopt_combo.v");
 
 compile (
-	 v_flags2 => ['+define+ISOLATE --stats'],
+	 verilator_flags2 => ['+define+ISOLATE --stats'],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_var_life.pl b/test_regress/t/t_var_life.pl
index 73a02e5c5..f9a8818de 100755
--- a/test_regress/t/t_var_life.pl
+++ b/test_regress/t/t_var_life.pl
@@ -8,7 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Version 2.0.
 
 compile (
-	 v_flags2 => ["--stats"],
+	 verilator_flags2 => ["--stats"],
 	 );
 
 if ($Self->{v3}) {
diff --git a/test_regress/t/t_var_pins_cc.pl b/test_regress/t/t_var_pins_cc.pl
index 9fbf82fc4..8f8385b71 100755
--- a/test_regress/t/t_var_pins_cc.pl
+++ b/test_regress/t/t_var_pins_cc.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (
diff --git a/test_regress/t/t_var_pins_sc1.pl b/test_regress/t/t_var_pins_sc1.pl
index 4c2b488e4..163d12056 100755
--- a/test_regress/t/t_var_pins_sc1.pl
+++ b/test_regress/t/t_var_pins_sc1.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (
diff --git a/test_regress/t/t_var_pins_sc2.pl b/test_regress/t/t_var_pins_sc2.pl
index 36624e1b8..e3a8522f0 100755
--- a/test_regress/t/t_var_pins_sc2.pl
+++ b/test_regress/t/t_var_pins_sc2.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (
diff --git a/test_regress/t/t_var_pins_sc32.pl b/test_regress/t/t_var_pins_sc32.pl
index c65cdc125..feca995f4 100755
--- a/test_regress/t/t_var_pins_sc32.pl
+++ b/test_regress/t/t_var_pins_sc32.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (
diff --git a/test_regress/t/t_var_pins_sc64.pl b/test_regress/t/t_var_pins_sc64.pl
index a22da2328..20a8cb72e 100755
--- a/test_regress/t/t_var_pins_sc64.pl
+++ b/test_regress/t/t_var_pins_sc64.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (
diff --git a/test_regress/t/t_var_pins_scui.pl b/test_regress/t/t_var_pins_scui.pl
index 0958273f1..26b69c522 100755
--- a/test_regress/t/t_var_pins_scui.pl
+++ b/test_regress/t/t_var_pins_scui.pl
@@ -7,6 +7,8 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 
+$Self->{vlt} or $Self->skip("Verilator only test");
+
 top_filename("t/t_var_pinsizes.v");
 
 compile (