[Publish] If DOS Game Dev is a rabbit hole then call me Alice

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posts/2022-01-11-if-dos-game-dev-is-a-rabbit-hole-then-call-me-alice.md

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+title: If DOS Game Dev is a rabbit hole then call me Alice
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+    - thoughts
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+---
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+The title for this article was first written in January 2021 soon after a week long deep dive into vintage computing and retro coding. The fact that I didn't begin writing the body of this article until December 2021 speaks volumes about how hectic 2021 was and how little of what I had aspired to complete in January of that year got done.
+
+## Seeking Thinking Sand
+
+In January, after dropping deep into the rabbit hole that is Roguelike games and their development; I discovered the joy that is retro-programming[^1] and the somewhat tight-knit community that surrounds it.
+
+Soon afterwards I ended up with the notion that it would make for an interesting project if I were to buy a vintage computer and then develop a game in Windows 10 with DOSBox as emulator to eventually be compiled and run on vintage hardware directly.
+
+This resulted in several long afternoons spent trawling eBay vintage hardware for an ideal computer. I don't have space for, nor want to risk shipping a big CRT and so the larger systems where excluded, and I narrowed my focus towards luggables. 
+
+Nothing makes a project more interesting than challenge and if you think developing for vintage hardware using modern day systems isn't challenging enough then hold my double espresso because I went one extra and decided anything 286 and above was too modern.
+
+Within the vintage computing community there are thriving groups of enthusiasts for Commodore, Acorn and ZX Spectrum computers. A result of this is that there are a lot of projects for 6502 and Zilog Z80 processors. While this would have given me a large pool of knowledge to dip into I wanted to do something that fewer living people had done before. To that end my focus narrowed tighter still on to the Intel 8080 and 8086 processors.
+
+In the end I found the Toshiba T1200 portable to be my ideal hardware platform. It's powered by the 16-bit Intel 8086 with 1MB of RAM, CGA graphics and in the case of the unit I bought, DOS 3.1 loaded from ROM, 1 x 1.44 720K floppy drive and a working 30MB hard disk[^2].
+
+## Narrowing down the problem
+
+With the hardware sorted my focus turned to how I was going to program a game using my modern Windows 10 computer. I didn't fancy learning a great deal of 8086 ASM and instead began looking for C/C++ compilers that could target 16-bit DOS.
+
+This actually proved to be the most difficult part of this whole endeavour until now because I didn't really know _what_ I was looking for. After spending the majority of a few weeks worth of afternoons researching I happened upon Open Watcom.
+
+In case you're unaware, Open Watcom C/C++ is an open source release of the Watcom IDE. Before being released under an open source licence, Watcom C/C++ was commercial software during the time period when my hardware of choice was a viable compile target. Better still Open Watcom is still being developed by an active community and has builds that run on Windows 10 while retaining its ability to target 16-bit DOS.
+
+At this point I now have physical hardware to develop for, a modern-ish toolchain and thanks to DOSBox an easy-to-use development environment for quickly testing builds without having to constantly transfer and run on my vintage hardware.
+
+## Unearthing decades old documentation
+
+Now that I had a viable development environment I needed to learn how to draw graphics to the screen and because my target hardware only supports CGA graphics that is what I needed to learn. Except it wasn't all that easy because a lot of the documentation isn't available online, or where it once was it has since been removed. I ended up reading through lecture notes from a university course taught in the 90s which finally helped things click into place.
+
+A lot of the problems I faced in finding out how things worked was not knowing the correct thing to search for.
+
+[^1]: There is something poetic about programming for systems long obsolete where documentation has not been digitised and knowledge has long since been buried in the Earth.
+
+[^2]: I will be writing more about this in the future, suffice to say I am happy the computer works and even more happy when I found the hard disk to have Windows 3.0 installed on a second partition!