A recent version of gawk has been successfully compiled and run "make test"
on the following:

Sun 4/490 running 4.1
NeXT running 2.0
DECstation 3100 running Ultrix 4.0 or Ultrix 3.1 (different config)
AtariST (16-bit ints, gcc compiler, byacc, running under TOS)
ESIX V.3.2 Rev D (== System V Release 3.2), the 386.  compiler was gcc + bison
IBM RS/6000 (see README.rs6000)
486 running SVR4, using cc and bison
SGI running IRIX 3.3 using gcc (fails with cc)
Sequent Balance running Dynix V3.1
Cray Y-MP8 running Unicos 6.0.11
Cray 2 running Unicos 6.1 (modulo trailing zeroes in chem)
VAX/VMS V5.x (should also work on 4.6 and 4.7)
VMS POSIX V1.0, V1.1
OpenVMS AXP V1.0
MSDOS - Microsoft C 5.1, compiles and runs very simple testing
BSD 4.4alpha

From:	ghazi@caip.rutgers.edu (Kaveh R. Ghazi):

arch				configured as:
----				--------------
Hpux 9.0			hpux8x
NeXTStep 2.0			next20
Sgi Irix 4.0.5 (/bin/cc)	sgi405.cc  (new file)
Stardent Titan 1500 OSv2.5	sysv3
Stardent Vistra (i860) SVR4	sysv4
SunOS 4.1.2			sunos41
Tektronix XD88 (UTekV 3.2e)	sysv3
Ultrix 4.2			ultrix41