COCOEMU1.0

A Tandy Color Computer 3 in the browser: the machine COCO TREK was tested on, MAME's, written again in JavaScript. Drop disk images, hard disks, programs or ROMs anywhere on the page.

Color Computer 3 · 512K Off Click the screen to type —

DRIVE 0Empty

Insert…

DRIVE 1Empty

Insert…

DRIVE 2Empty

Insert…

DRIVE 3Empty

Insert…

HARD DISK 0Empty

Attach…

HARD DISK 1Empty

Attach…

Files on drive 0

Add files…

Name	Kind	Bytes

Disk BASIC's directory. Files dropped here are written to the disk; the program sees them the next time it reads the directory.

Machine—

Memory

Monitor

Speed

Cartridge slot

Changing the memory, monitor or slot starts the machine again. Reset is the button on the back: memory is kept.

ROMs

NONESystem ROM: Super Extended Color BASIC (coco3.rom, 32K)

NONEDisk ROM: Disk Extended Color BASIC (disk11.rom, 8K)

Load ROM files…

The ROMs are not part of this page. Load your own (MAME's coco3.zip will do); they stay in this browser. Without them, COCO TREK and other programs that take the machine over start without BASIC.

Keyboard and joystick

Keys

Joystick

End with ENTER

the sample disk, in drive 0

Screen and sound

Artifact colours

Volume

The GIME's 16 palette registers

Printer600 baud

Links

On a web server, the page sets itself up from its address: the query string, or the same after #. A link can name disks, a hard disk, a program, the machine and keys to type.

Parameter	Values	Does
`disk`, `disk1` … `disk3`	an address, `trek`	Floppies for drives 0–3: an image, or a zip of one. Another site's file needs that site to allow it (CORS). An address alone after `?` is drive 0.
`hd`, `hd1`	an address	Virtual hard disks 0 and 1, read in pieces as the program asks for them when the server allows ranges.
`bin`	an address	A machine-language program (LOADM format) to load and run.
`roms`	an address	A folder holding `coco3.rom` and `disk11.rom`, or a zip of them, on your own server.
`cart`	an address	A ROM pack for the slot, in place of the disk controller.
`ram`	`128`, `512`, `2048`, `8192`	Memory, in K.
`monitor`	`rgb`, `composite`	The monitor the colours are shown for.
`speed`, `turbo`	`1`, `2`, `4`, `max`; `0`/`1`	Times the real machine's speed; fast while a disk turns.
`type`	text	Typed once the machine has started (`\|` or `\r` for ENTER); `typewait` sets the frames to wait (90).
`trek`	`r`, `c`	COCO TREK's answer for its monitor question, when it starts without the ROMs.
`keys`, `joy`	`natural`, `position`; `mouse`, `pad`	How keys are sent; the joystick.
`sound`, `volume`	`0`/`1`, 0–100	Sound on or off, and its volume.
`autostart`, `pause`	`0`, `1`	Insert without starting; start paused.

This setup as a link

Keyboard

Click the screen first. By character, what you type arrives as the same character, with the Color Computer's SHIFT added where its keyboard needs it (" is SHIFT and 2). By position, each key is the Color Computer key in its place, for programs that read the keyboard themselves.

Your key	Color Computer key
`Esc`, `End`, `Pause`	BREAK
`Home`, `Delete`	CLEAR
`Return`	ENTER
`Backspace`	← (the left arrow, which rubs out)
arrows	the four arrow keys
`Alt`, `Ctrl`, `F1`, `F2`	ALT, CTRL, F1, F2
`Shift`	SHIFT (with letters, SHIFT-0 for lower case)
`Insert`	SHIFT-@ pause, as in BASIC listings

The joystick is the right one (the first port). With the mouse, the pointer on the screen is the stick and its button the fire button; a game controller's left stick and first two buttons work the same.

Disks and files

Drop files anywhere on the page, or on a drive to put them there. Floppies go in the first empty drive; drives 2 and 3 are fitted when a disk goes in.

File	Goes
`.dsk` `.jvc` `.vdk` `.dmk` `.os9` `.sdf`	A floppy drive. 35 and 40 tracks, one side or two; 80-track images fit a quad-density drive, made so when the disk goes in.
`.vhd` `.hdd`	A virtual hard disk at $FF80–$FF86 (MAME's), up to 4 GB. Large images are read in pieces as the program asks for them.
`.bin`	Run: with the ROMs, from a disk of its own by `LOADM` and `EXEC`; without them, at once.
`.bas`	Put on a disk of its own and `RUN`.
`.rom` `.ccc`	The system or disk ROM, recognised by its contents; anything else is a ROM pack.
`.zip`	Opened: the one file in it that fits, or a choice.

Saving

A changed floppy is marked CHANGED; Save gives you the image. A hard disk opened with Open to save… (in Chrome and Edge) is written back into the file itself; otherwise Save gives you a copy with the changes, assembled from the original file without reading it whole.

Embedding

Put the page in a frame and drive it with messages, or call it from a script on the page itself.

<iframe src="cocoemu/index.html?disk=disks/COCOTREK.DSK&type=RUN%22TREK%22|"
        width="800" height="700" allow="fullscreen; autoplay"></iframe>

frame.contentWindow.postMessage(
  { type: 'cocoemu', cmd: 'type', text: 'DIR\r' }, '*');

window.addEventListener('message', (e) => {
  if (e.data.type === 'cocoemu' && e.data.event === 'print')
    console.log(e.data.text);
});

Commands

load (url or data, name, drive), eject (drive), power, reset, pause, resume, type (text), key (name, down), set (name, value), state, text (the screen as text), peek (addr, n), screenshot. Each is answered with { type: 'cocoemu', reply, id, result }.

Events

ready, power, disk, started, halted (a program restarted the machine with no BASIC to go to), print (a line from the printer), paused, resumed.

About

COCO TREK was tested on MAME 0.264's Color Computer 3. This is that machine written again in JavaScript, and held to it. The 6809 makes the same bus cycles; the GIME, the 6821s, the cartridge slot's lines, the WD1773 with its digital PLL reading the flux of each track, and MAME's own scheduler keep the same time. Run side by side, the two agree instruction by instruction through millions of instructions, and COCO TREK's own tests print the same lines and take the same pictures on both.

The sample disk is COCO TREK 1.0, by Bill Martens, WPM Productions, published by A.P.P.L.E. Without the ROMs it starts as its loader would start it: TREK.BIN is loaded as LOADM loads it and run, with no BASIC behind it.