Lua for Open Watcom

This repository contains wmake style makefiles and patches to build Lua on Open Watcom 1.9 or later. The primary goal was to allow Lua scripts to be run on DOS systems in real mode but has expanded to include all Open Watcom targets that don't require external dependencies to build.

Runtime Requirements

Lua for Watcom binaries can run on a number of legacy systems as well as some modern ones.

Absolute Minimum Requirements

These are the absolute lowest system requirements needed for a PC to run LUA16.EXE.

Type	Requirement	Remarks
CPU	8086 compatible	Compatibles like the Intel 8088, NEC V20, 286, 386 etc Machine emulators provided as an alternative for other ISAs 86Box (GitHub) DOSBox-X (GitHub) PCem (GitHub)
Operating System	PC-DOS 2.0	FreeDOS DOSBox-X (GitHub) SvarDOS
Random Access Memory	At least 512 kilobytes of base system memory	Any memory above 640 kilobytes is inaccessible to all real mode DOS programs
Storage	At least 150 kilobytes of free disk space	Can be ran directly from a diskette on machines without a hard drive

Binary Native Targets

Since Open Watcom can produce binaries for several operating systems, each binary has been given a unique name to distinguish the native Operating System (OS) and Instruction Set Architecture (ISA) it is intended for.

Binary Name	Native OS	Native ISA
LUA16.EXE	Real mode DOS	8086
LUA21.EXE	OS/2 1.2	80286
LUA22.EXE	OS/2 2.0	80386
LUA4G.EXE	DOS4GW extender	80386
LUANT.EXE	Windows 95	80386

Binary Compatibility Matrix

Some OSes can run binaries intended for another out of the box. Do keep in mind, however, that in most of these cases the OS is newer and has higher minimum requirements.

Operating System	Minimum OS ISA(s)	LUA16.EXE	LUA21.EXE	LUA22.EXE	LUA4G.EXE	LUANT.EXE
DOS 2.x - 4.x Windows 1.x - 3.x	8086	Yes	No	No	No	No
DOS 5.x - 7.x	8086 80386SX	Yes	No	No	No Yes	No
OS2 1.0 - 1.1	80286	Yes	No	No	No	No
OS2 1.2 - 1.3	80286	Yes	Yes	No	No	No
OS2 2.x	80386SX	Yes	Yes	Yes	No	No
OS2 3.x	80386SX	Yes	Yes	Yes	Yes	No
OS2 4.x	80486SX	Yes	Yes	Yes	Yes	No
Windows 95	80386SX	Yes	No	No	Yes	Yes
Windows 98	80486DX 80486SX+80487SX	Yes	No	No	Yes	Yes
Windows 2000 - ME	80586	No	No	No	No	Yes
Windows XP	80586 x86_64	No	No	No	No	Yes
Windows Vista - 10	80686 x86_64	No	No	No	No	Yes
Windows 11	x86_64	No	No	No	No	Yes

Build Requirements

To build Lua with Open Watcom you will need the following:

Requirement	Sources
Lua 5.4 source code (or build machine with git submodules)	lua.org (GitHub)
Open Watcom 1.9 (or later)	openwatcom.org (GitHub) FreeDOS Bonus CD (FDIMPLES) SvarDOS (PKGNET repository)
Operating System supported by Open Watcom (at least MS-DOS 5.0)	FreeDOS DOSBox-X (GitHub) SvarDOS
80386 compatible processor* *Any AMD or Intel CPU made in the last 3 decades is compatible. Machine emulators provided as an alternative for other ISAs	86Box (GitHub) DOSBox-X (GitHub) PCem (GitHub) Qemu (GitLab)
A patching utility	GNU Patch DifPat

If in doubt, DOSBox-X can be used on a modern machine

How to build

1. Extract Luas source code to the Lua folder. This can be achieved in two ways:

   • Use git submodules init then git submodules update --recursive to get the sources directly from the Lua mirror repository
   • Download the Lua 5.4.x sources tarballs from https://lua.org/ftp/, extract them and copy all files in src to Lua

2. Patch the source code for Watcom (optional):

   GNU Patch	DifPat
   patch -p0 -i lua.pat	pat lua.pat .

   If no patching program is available mimic the changes in each .pat file manually. Patch changes are minimal and only serve to silence Watcom compiler warnings

3. Build Lua with the following commands:

   Make Command	Binary File	System	Processor
   wmake -f wm_dos16.mak	dist/bin/lua16.exe	PC-DOS 2.0+	8086/8088 or later
   wmake -f wm_dos4g.mak	dist/bin/lua4g.exe	MS-DOS 5.0+	80386 or later
   wmake -f wm_os216.mak	dist/bin/lua21.exe	OS/2 1.2	80286 or later
   wmake -f wm_os232.mak	dist/bin/lua22.exe	OS/2 2.0	80386 or later
   wmake -f wm_winnt.mak	dist/bin/luant.exe	Windows 95+	80386 or later

Other targets may work but are untested