Updated readme

.gitignore

@@ -5,3 +5,6 @@ Cargo.lock
 
 perf.data
 perf.data.old
+
+binaries/*/*.asm
+binaries/*/*.bin

README.md

@@ -8,13 +8,54 @@ 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.
+Currently it can simulate Computie (68000), the TRS-80 Model I (Z80), and the
+Sega Genesis.  Support for the Macintosh 512k is partially implemented but the
+ROM still wont boot.
 
 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)
 
 
+Sega Genesis/MegaDrive
+----------------------
+
+From the project root, run the following:
+```
+cargo run -p moa-minifb --release --bin moa-genesis -- <ROM FILE>
+```
+
+The Genesis emulator is slowly coming along.  It can play a decent number of
+game, but some games wont display anything, and a few games run but don't
+respond to the controller input.  Games that require extra memory or nvram that
+would normally be inside the cartridge usually crash.
+
+It only supports NTSC mode at the moment, and only VDP mode 5 (not the backwards
+compatible mode 4).  I've rewritten the frame drawing code to operate pixel by
+pixel, so it will now draw all the layers, including the window, sort out the
+priority of the pixels, and almost accurately implement the shadow and highlight
+colour modes.  Audio is not implemented yet.
+
+There are still some problems like the colour of Tails in the Sonic 2 title
+screen being off.  I'm not sure why that happens, but it could be trying to
+update the colours during the drawing of the frame, and since the code is
+drawing the entire frame at once when the vertical blanking period is reached,
+the on-the-fly changes don't have an affect.
+
+![alt text](images/sega-genesis-sonic2-title.png)
+
+The game play is mostly working but the time in the upper left corner doesn't
+seem to progress
+
+![alt text](images/sega-genesis-sonic2-start.png)
+
+![alt text](images/sega-genesis-sonic2-bridge.png)
+
+Earthworm Jim was working before I fixed the controller behaviour in Sonic 2,
+which seems to have broken it in Earthworm Jim (and Mortal Kombat 1).
+
+![alt text](images/sega-genesis-earthworm-jim.png)
+
+
 Computie
 --------
 
@@ -54,45 +95,6 @@ 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
-
-![alt text](images/sega-genesis-sonic2-title.png)
-
-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
-
-![alt text](images/sega-genesis-sonic2-start.png)
-
-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
-
-![alt text](images/sega-genesis-sonic2-bridge.png)
-
-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
-
-![alt text](images/sega-genesis-earthworm-jim.png)
-
 
 General Options
 ---------------
@@ -114,3 +116,8 @@ 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.
 
+The `-x` or `--speed` option, when given a decimal number, will multiply that
+number by the milliseconds per frame, increasing or decreasing the gameplay
+clock relative to the frontend's update loop.  Setting it to 0.5 slows the game
+down to half speed and setting it to 2 doubles the speed.
+