mirror of
https://github.com/transistorfet/moa.git
synced 2024-11-25 15:33:08 +00:00
110 lines
4.4 KiB
Markdown
110 lines
4.4 KiB
Markdown
|
|
Moa
|
|
===
|
|
|
|
###### *Started September 26, 2021*
|
|
|
|
Moa is an emulator/simulator for computers using various 68000 and Z80 CPUs and
|
|
peripherals. The original idea was to emulate the computer I had built as part
|
|
of the [Computie project](https://jabberwocky.ca/projects/computie/).
|
|
|
|
Currently it can simulate Computie (68000) and the TRS-80 Model I (Z80), and I'm
|
|
working on supporting the Macintosh 512k and Sega Genesis.
|
|
|
|
For more detail, check out this post about how I started the project:
|
|
[Making a 68000 Emulator in Rust](https://jabberwocky.ca/posts/2021-11-making_an_emulator.html)
|
|
|
|
|
|
Computie
|
|
--------
|
|
|
|
For Computie, it can do everything the 68k-SMT board can do, including run the
|
|
monitor program and load the Computie OS kernel and boot it from the
|
|
CompactFlash card. To run it:
|
|
```
|
|
cargo run -p moa-console --bin moa-computie
|
|
```
|
|
It will open two PTYs: one for the serial terminal, and one for the SLIP
|
|
connection. Once open, it will try to launch both `pyserial-miniterm` as a
|
|
separate process and connect to the Computie PTY. It will also launch
|
|
`slattach` with the associated setup commands to create the SLIP device on the
|
|
host, and set up host routing. The exact commands in
|
|
`src/machines/computie.rs` might need to be adjusted to work on different
|
|
hosts.
|
|
|
|
TRS-80
|
|
------
|
|
|
|
For the TRS-80, it can run Level I or Level II Basic, but it doesn't yet
|
|
support a cassette tape drive or floppy drive. I haven't tested it that
|
|
thoroughly either, so any help with it would be welcome. I mostly made it to
|
|
test the Z80 cpu implementation in a simpler computer before I used in the
|
|
Genesis emulator. The frontend uses the
|
|
[`minifb`](https://github.com/emoon/rust_minifb) rust crate to open a window
|
|
and render the characters to screen, as well as accept input from the keyboard.
|
|
```
|
|
cargo run -p moa-minifb --release --bin moa-trs-80
|
|
```
|
|
By default it will start Level I Basic. To use the other rom, add the option
|
|
`--rom binaries/trs80/level2.rom`
|
|
|
|
|
|
|
|
The characters are being drawn pixel by pixel (6x8) using characters I drew
|
|
using [this handy website](https://maxpromer.github.io/LCD-Character-Creator/).
|
|
They aren't a perfect match of the characters used by the TRS-80
|
|
|
|
Sega Genesis/MegaDrive
|
|
----------------------
|
|
|
|
It can be run with:
|
|
```
|
|
cargo run -p moa-minifb --release --bin moa-genesis -- <ROM FILE>
|
|
```
|
|
|
|
The Genesis emulator is a work in progress. It can play a few games but some
|
|
games won't run because the bank switching for the Z80 coprocessor is not
|
|
working yet, and some games will hang waiting for the Z80 to respond. For the
|
|
video processor, the window layer is not drawn and the layer priority is not
|
|
handled. The horizontal scroll also doesn't work on a line-by-line basis so it
|
|
tends to be quite jerky as you move, with the sprites and cells misaligned
|
|
until you've moved one complete cell over (8x8 pixels).
|
|
|
|
On the Sonic 2 title screen, the colours for Tails are wonky, probably because
|
|
there's some trickery going on to get more than 16 colours per line, but the
|
|
emulator currently renders the whole frame at once instead of line by line, so
|
|
changes that should be made while the screen is updating don't show up
|
|
|
|
|
|
|
|
The game play is mostly working but the bottom of the clouds should be a
|
|
different colour, probably because highlight/shadow colours are not yet
|
|
supported. The time in the upper left corner also doesn't seem to progress
|
|
|
|
|
|
|
|
I'm not yet sure why the clouds in the background are cut off suddenly. They
|
|
change in a glitchy way when you move around
|
|
|
|
|
|
|
|
There are some graphics glitches in Earthworm Jim, but it's almost playable if it
|
|
wasn't for the 'jump' button, which only makes him jump a few pixels
|
|
|
|
|
|
|
|
|
|
General Options
|
|
---------------
|
|
|
|
By default, the minifb frontend will scale the window by 2. This can be
|
|
changed with the `--scale [1,2,4]` option.
|
|
|
|
The `-d` or `--debugger` option will make the emulator start the debugger
|
|
before running. There is a simple built-in debugger for stepping through
|
|
the rom instructions being emulated. The state of the CPU registers will
|
|
be displayed after each instruction, breakpoints can be set, memory contents
|
|
can be examined, and memory locations can be modified. This has helped a lot
|
|
with tracking down errors in the emulator itself.
|
|
|