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68 lines
2.4 KiB
Markdown
68 lines
2.4 KiB
Markdown
# Sega Master System
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The Sega Master System was a popular gaming console running on z80. It has a
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simple, solid design and, most interestingly of all, its even more popular
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successor, the Megadrive (Genesis) had a z80 system for compatibility!
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This makes this platform *very* scavenge-friendly and worth working on.
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[SMS Power][smspower] is an awesome technical resource to develop for this
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platform and this is where most of my information comes from.
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This platform is tight on RAM. It has 8k of it. However, if you have extra RAM,
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you can put it on your cartridge.
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## Related recipes
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This recipe is for installing a minimal Collapse OS system on the SMS. There
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are other recipes related to the SMS:
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* [Interfacing a PS/2 keyboard](kbd/README.md)
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## Gathering parts
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* [zasm][zasm]
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* A Sega Master System or a MegaDrive (Genesis). (I have only tested on a
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MegaDrive so far)
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* A Megadrive D-pad controller.
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* A way to get an arbitrary ROM to run on the SMS. Either through a writable
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ROM card or an [Everdrive][everdrive].
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## Build the ROM
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Running `make` will produce a `os.sms` ROM that can be put as is on a SD card
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to the everdrive or flashed as is on a writable ROM cart. Then, just run the
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thing!
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## Usage
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On boot, you will get a regular Collapse OS BASIC shell. See the rest of the
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documentation for shell usage instructions.
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The particularity here is that, unlike with the RC2014, we don't access Collapse
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OS through a serial link. Our input is a D-Pad and our output is a TV. The
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screen is 32x28 characters. A bit tight, but usable.
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D-Pad is used as follow:
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* There's always an active cursor. On boot, it shows "a".
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* Up/Down increase/decrease the value of the cursor.
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* Left/Right does the same, by increments of 5.
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* A button is backspace.
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* B button skips cursor to next "class" (number, lowcase, upcase, symbols).
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* C button "enters" cursor character and advance the cursor by one.
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* Start button is like pressing Return.
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Of course, that's not a fun way to enter text, but using the D-Pad is the
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easiest way to get started which doesn't require soldering. Your next step after
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that would be to [build a PS/2 keyboard adapter!](kbd/README.md)
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## Slow initialization in emulation
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When running under the emulator, video initialization is slow, it takes several
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seconds. It's the emulator's fault. On real hardware, it's not as slow.
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[smspower]: http://www.smspower.org
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[everdrive]: https://krikzz.com
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[zasm]: ../../tools/emul
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