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+---
+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<stdio.h>
+
+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) $(bin)
+```
+
+Where, `main.c`
+```c
+void hello(void);
+
+int main(void)
+{
+    hello();
+    return 0;
+}
+```
+
+and `hello.c`
+
+```c
+/* hello.c */
+#include <stdio.h>
+
+void hello(void)
+{
+    printf("Hello!");
+}
+```
+
+To compile into `tizts.com` simply run `wmake`
+
+```bash
+$ 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 <stdio.h>
+
+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...*
+
+