I tried to configure and build the package on SCO Unix/386 
System V Rel 3.2v4.2. I ran into several issues with the build.
The first time the build broke was when missing header files:

	(cd EnginePl; make config)
	. ./SETVARS;for i in TopComp EnginePl Wam2Ma Ma2Asm Linedit   BipsPl Pl2Wam Fd2C EngineFD BipsFD;do (cd $i; make) || exit 1; done;\
	(cd TopComp; make gprolog)
	gplc -c -C '-O3 ' machine.c
machine.c:247: sys/mman.h: No such file or directory
machine.c:478: sys/siginfo.h: No such file or directory
compilation failed
*** Error code 1
*** Error code 1

I compensated by making sure M_USE_MMAP is undefined, then ran
into the next problem:


	(cd EnginePl; make config)
	. ./SETVARS;for i in TopComp EnginePl Wam2Ma Ma2Asm Linedit   BipsPl Pl2Wam Fd2C EngineFD BipsFD;do (cd $i; make) || exit 1; done;\
	(cd TopComp; make gprolog)
	gcc -c -m386 -fomit-frame-pointer -O3  linedit.c
linedit.c: In function `LE_FGets':
linedit.c:380: `KEY_EXT_HOME' undeclared (first use this function)
linedit.c:380: (Each undeclared identifier is reported only once
linedit.c:380: for each function it appears in.)
linedit.c:387: `KEY_EXT_END' undeclared (first use this function)
linedit.c:394: `KEY_EXT_LEFT' undeclared (first use this function)
linedit.c:403: `KEY_EXT_RIGHT' undeclared (first use this function)
linedit.c:428: `KEY_EXT_DELETE' undeclared (first use this function)
linedit.c:438: `KEY_CTRL_EXT_HOME' undeclared (first use this function)
linedit.c:458: `KEY_CTRL_EXT_END' undeclared (first use this function)
linedit.c:519: `KEY_CTRL_EXT_LEFT' undeclared (first use this function)
linedit.c:530: `KEY_CTRL_EXT_RIGHT' undeclared (first use this function)
linedit.c:605: `KEY_EXT_INSERT' undeclared (first use this function)
linedit.c:634: `KEY_EXT_UP' undeclared (first use this function)
linedit.c:653: `KEY_EXT_DOWN' undeclared (first use this function)
linedit.c:700: `KEY_EXT_PAGE_UP' undeclared (first use this function)
linedit.c:710: `KEY_EXT_PAGE_DOWN' undeclared (first use this function)
linedit.c:795: storage size of `t' isn't known
*** Error code 1
*** Error code 1


This was easy to fix, the KEY_EXT_* cases all have alternatives
so I simply commented them out. The last problem in linedit.c was
solved by adding the following 4 lines to linedit.c just after
the other included header files (before the boxed comment Constants):

#if !defined(NO_USE_SELECT)
#include <sys/times.h>
#include <sys/select.h>
#endif

These are needed to pick up the definition for struct timeval on
SCO Unix/386 System V Rel 3.2v4.2. The next problem encountered
was:

	(cd EnginePl; make config)
	. ./SETVARS;for i in TopComp EnginePl Wam2Ma Ma2Asm Linedit   BipsPl Pl2Wam Fd2C EngineFD BipsFD;do (cd $i; make) || exit 1; done;\
	(cd TopComp; make gprolog)
	gcc -c -m386 -fomit-frame-pointer -O3  stty.c
stty.c: In function `LE_Screen_Size':
stty.c:202: storage size of `ws' isn't known
*** Error code 1
*** Error code 1

This is easily fixed by adding -D_IBCS2 (this is required
on SCO Unix/386 System V Rel 3.2v4.2, the header termios.h
conditionally defines struct winsize only when _IBCS2 is defined).

The next problem proves to be more challenging:


	(cd EnginePl; make config)
	. ./SETVARS;for i in TopComp EnginePl Wam2Ma Ma2Asm Linedit   BipsPl Pl2Wam Fd2C EngineFD BipsFD;do (cd $i; make) || exit 1; done;\
	(cd TopComp; make gprolog)
`liblinedit.a' is up to date.
	gplc -c foreign.wam
Assembler: /u/usr/nefth/tmp/gplcBAAa04144.s
	aline 7	: syntax error
	aline 7	: illegal character
	aline 14	: syntax error
	aline 14	: illegal character
	aline 22	: syntax error
	aline 22	: illegal character
	aline 56	: syntax error
	aline 56	: illegal character
	aline 64	: syntax error
	aline 64	: illegal character
	aline 76	: Section definition must have attributes
	aline 85	: Illegal mnemonic
	aline 85	: syntax error
	aline 86	: syntax error
error trying to execute as: unknown errorcompilation failed
*** Error code 1
*** Error code 1


	(cd EnginePl; make config)
	. ./SETVARS;for i in TopComp EnginePl Wam2Ma Ma2Asm Linedit   BipsPl Pl2Wam Fd2C EngineFD BipsFD;do (cd $i; make) || exit 1; done;\
	(cd TopComp; make gprolog)
`liblinedit.a' is up to date.
	gplc -W  --no-redef-error foreign.pl
error trying to execute pl2wam: No such file or directory
compilation failed
*** Error code 1
*** Error code 1


The i386 assembly produced is suitable for ELF, but not
for COFF objects. 

Do you know if someone is working on a port to System V COFF 
object format?