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////	Chip8-TI68k: A full-featured (S)CHIP-8 emulator for your TI calculator
////			By: Peter Lafreniere <[email protected]>
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Introduction:
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Have you ever wanted to play games on your calculator? Of course you have.
You don't have to lie.

How about CHIP-8 games? If you've never heard of CHIP-8, then you're not alone.

CHIP-8 is a format of retro game roms that are particularly well-suited to
running on graphing calculators. Over time, there has been a huge amount of
extensions and implementations that are often not compatible.

This program is designed to be compatible with the vast majority of roms found
on the internet. It supports SCHIP and some XO-CHIP features in addition to
the base CHIP-8 spec.

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Usage:
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First, you need CHIP-8 roms. They can be found easily with the use of your
preferred internet search engine. Unlike roms for true consoles, these roms
tend to be perfectly legal to distribute online. I suggest starting by looking
at the roms available at <https://github.com/JohnEarnest/chip8Archive>.

Preprocessor
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Once you have your roms, you must transform them into files suitable for your
calculator. This can be done with the ch8ti-prep.exe utility found in this
project.

To use ch8ti-prep, you need to use the command line terminal. Just run:

"./ch8ti-prep.exe -c <ti89|ti92p|v200> [name of rom to process]"
You should find your processed rom in the same folder as your input rom.
For example:

"./ch8ti-prep.exe -c ti89 roms/cave.ch8"
will produce a file named cave.89y in the folder roms.

ch8ti-prep has several other options controlling output. You can see them by
running:
"./ch8ti-prep.exe --help"

Calculator
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The only files that you will need on your calculator are the processed roms
and the ch8ti program that matches your calculator model.

Once those have been transferred, run ch8ti() and you will be prompted to
select the file you wish to play.

Alternatively, you can call ch8ti with the rom/savestate you wish to play.
e.g. "ch8ti("cave")"

The CHIP-8 keyboard maps to the calculator keyboards like so:
  |1|2|3|C|
  |4|5|6|D|
  |7|8|9|E|
  |A|0|B|F|
      ||
      ||
      \/
  |7|8|9|x|
  |4|5|6|-|
  |1|2|3|+|
  |0|.|-|e|

Special keys:
Esc can be used to exit the program and F1 can be used to open the savestate
dialog.

Also note that the up, down, left, and right arrow keys are bound to the 5, 8,
7, and 9 CHIP8 keys, respectively. 2nd (and HAND) can similarly be used as the
CHIP8 6 key.

You will rarely use a key other than an arrow key or 2nd.

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About:
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This program was developed by one high school student during their (surprisingly)
limited free time. If you have any comments, questions, or suggestions, please
feel free to reach out to me (Peter Lafreniere) with them.

The source code should be included along with the executables. It's decently
hackable, so feel free to hack at it all you would like.

This emulator implements every CHIP8 and SCHIP opcode, as well as several
Octo extensions. You should not have any issue running monochrome SCHIP roms.

Note: The persistent storage opcodes are faked. There is no persistence past
the end of the current emulator invocation.

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History:
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v0.9 (2022-10-12)
 - Initial public availability.
 - Marked as pre-release.

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Thanks:
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A big thank you is owed to the developers of the tigcc/gcc4ti projects. This
program wouldn't be anywhere without the tools and documentation provided by
these people.

Tobias Langhoff for their high quality documentation on CHIP8.
<https://chip-8.github.io/extensions/>

John Earnest for their Octo interpreter, which I used as a reference to debug
against. John also curated the Chip8 Community Archive, a large collection of
CHIP8 roms.