From ea7a6ce794dbda1a7eded1d5e663897d46d21fa2 Mon Sep 17 00:00:00 2001 From: Navan Chauhan Date: Fri, 15 Mar 2024 15:00:41 -0600 Subject: add post about compiling for dos --- ...2024-03-15-setting-up-macos-for-8088-dos-dev.md | 267 +++++++++++++++++++++ 1 file changed, 267 insertions(+) create mode 100644 Content/posts/2024-03-15-setting-up-macos-for-8088-dos-dev.md (limited to 'Content/posts/2024-03-15-setting-up-macos-for-8088-dos-dev.md') diff --git a/Content/posts/2024-03-15-setting-up-macos-for-8088-dos-dev.md b/Content/posts/2024-03-15-setting-up-macos-for-8088-dos-dev.md new file mode 100644 index 0000000..15161f5 --- /dev/null +++ b/Content/posts/2024-03-15-setting-up-macos-for-8088-dos-dev.md @@ -0,0 +1,267 @@ +--- +date: 2024-03-15 13:16 +description: This goes through compiling Open Watcom 2 and creating simple hello-world exampls +tags: DOS, x86, macOS +draft: false +--- + +# Cross-Compiling Hello World for DOS on macOS + +Technically this should work for any platform that OpenWatcom 2 supports compiling binaries for. Some instructions are based on [a post at retrocoding.net](https://retrocoding.net/openwatcom-gateway-to-ancient-world-of-x86), + and [John Tsiombikas's post](http://nuclear.mutantstargoat.com/articles/retrocoding/dos01-setup/#hello-world-program) + +## Prerequisites + +You should already have XCode / Command Line Tools, and Homebrew installed. To compile Open Watcom for DOS you will need DOSBox (I use DOSBox-X). + +```bash +brew install --cask dosbox-x +``` + +## Compiling Open Watcom v2 + +*If this process is super annoying, I might make a custom homebrew tap to build and install Open Watcom* + +```bash +git clone https://github.com/open-watcom/open-watcom-v2 +cp open-watcom-v2/setvars.sh custom_setvars.sh +``` + +Now, edit this `setvars.sh` file. My file looks like this: + +```bash +#!/bin/zsh +export OWROOT="/Users/navanchauhan/Developer/8088Stuff/open-watcom-v2" +export OWTOOLS=CLANG +export OWDOCBUILD=0 +export OWGUINOBUILD=0 +export OWDISTRBUILD=0 +export OWDOSBOX="/Applications/dosbox-x.app/Contents/MacOS/dosbox-x" +export OWOBJDIR=binbuildV01 +. "$OWROOT/cmnvars.sh" +echo "OWROOT=$OWROOT" +cd "$OWROOT" +``` + +Note, your `OWRTOOT` is definitely going to be in a different location. + +```bash +source ./custom_setvars.sh +./build.sh +./build.sh rel +``` + +This will build, and then copy everything to the `rel` directory inside `open-watcom-v2` directory. Since I ran this on an Apple Silicon Mac, + all the binaries for me are in the `armo64` directory. You can now move everything inside the rel folder to another location, or create a simple + script to init all variables whenever you want. + +I like having a script called `exportVarsForDOS.sh` + +```bash +#!/bin/zsh + +export WATCOM=/Users/navanchauhan/Developer/8088Stuff/open-watcom-v2/rel +export PATH=$PATH:$WATCOM/armo64 +export EDDAT=$WATCOM/eddat + +# For DOS 8088/8086 development +export INCLUDE=$WATCOM/h +export LIB=$WATCOM/lib286 # You don't really need this +``` + +Then, when you need to load up these variables, you can simply run `source exportVarsForDOS.sh` or `. exportVarsForDOS.sh` + +## Hello World + +### Buliding without any Makefiles + +Create a new file called `example1.c` + +```c +#include + +int main() { + printf("Hello World!"); + return 0; +} +``` + +First we compile the code: + +```bash +$ wcc example1.c +Open Watcom C x86 16-bit Optimizing Compiler +Version 2.0 beta Mar 15 2024 13:11:55 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1984-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. +example1.c: 7 lines, included 818, 0 warnings, 0 errors +Code size: 19 +``` + +Then, link to make an executable: + +```bash +$ wlink name example1.exe system dos file example1.o +Open Watcom Linker Version 2.0 beta Mar 15 2024 13:10:09 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1985-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. +loading object files +searching libraries +creating a DOS executable +``` + +If you want to test this executable, jump to the section titled `Testing with DOSBox-X` below. + +### Simple Makefile + +```makefile +obj = main.o hello.o +bin = tizts.com + +CC = wcc +CFLAGS = -0 +LD = wlink + +$(bin): $(obj) + $(LD) name $@ system dos file main.o file hello.o + +.c.o: + $(CC) $(CFLAGS) $< + +clean: + rm $(obj) $(bin) +``` + +Where, `main.c` +```c +void hello(void); + +int main(void) +{ + hello(); + return 0; +} +``` + +and `hello.c` + +```c +/* hello.c */ +#include + +void hello(void) +{ + printf("Hello!"); +} +``` + +To compile into `tizts.com` simply run `wmake` + +```bash +$ wmake +➜ simple-cpp wmake +Open Watcom Make Version 2.0 beta Mar 15 2024 13:10:16 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1988-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. + wcc -0 main.c +Open Watcom C x86 16-bit Optimizing Compiler +Version 2.0 beta Mar 15 2024 13:11:55 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1984-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. +main.c(8): Warning! W138: No newline at end of file +main.c: 8 lines, included 53, 1 warnings, 0 errors +Code size: 12 + wcc -0 hello.c +Open Watcom C x86 16-bit Optimizing Compiler +Version 2.0 beta Mar 15 2024 13:11:55 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1984-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. +hello.c: 8 lines, included 818, 0 warnings, 0 errors +Code size: 17 + wlink name tizts.com system dos file main.o file hello.o +Open Watcom Linker Version 2.0 beta Mar 15 2024 13:10:09 +Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved. +Portions Copyright (c) 1985-2002 Sybase, Inc. All Rights Reserved. +Source code is available under the Sybase Open Watcom Public License. +See https://github.com/open-watcom/open-watcom-v2#readme for details. +loading object files +searching libraries +creating a DOS executable +``` + +### Using CMake + +Create a file called `CMakeLists.txt` + +```CMake +project(hello) + +set(SOURCES abc.c) + +add_executable(hello ${SOURCES}) +``` + +Where, `abc.c` is: + +```c +#include + +int main() { + printf("Does this work?"); + return 0; +} +``` + +```bash +mkdir build +cd build +``` + +And build using CMake + +``` +cmake -DCMAKE_SYSTEM_NAME=DOS -DCMAKE_SYSTEM_PROCESSOR=I86 -DCMAKE_C_FLAGS="-0 -bt=dos -d0 -oaxt" -G "Watcom WMake" ../.. +``` + +There you have it. Three different ways to compile a C program on a macOS device in 2024 that can run on an IBM PC 5150 (which was released in 1981!) + +## Testing with DOSBox-X + +```bash +cp example1.exe ~/Downloads +/Applications/dosbox-x.app/Contents/MacOS/dosbox-x +``` + +In DOSBox-X we now mount the `~/Downloads` folder as our `C:` drive + +``` +mount C ~/Downloads +``` + +Switch to the C drive + +``` +C: +``` + +Run the program: + +``` +example1 +``` + +![Running our program in DOSBox-X](/assets/posts/dosbox/hello-world.png) + +*My DOSBox setup might look slightly different than yours...* + + -- cgit v1.2.3