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Forum Index : Microcontroller and PC projects : A TRS-80 on the Colour Maximite 2

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matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 12172
Posted: 10:37am 11 Nov 2026
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A TRS-80 on the Colour Maximite 2

A new program in the 7.00.00RC5 programs zip, for the Generation 1 and the Generation 2. The firmware is unchanged: download the zip again and copy its trs80 folder to the card.

https://github.com/UKTailwind/CMM2V1.5/releases/tag/v7.00.00RC5


What it is
It is sdltrs, Mark Grebe's and Jens Guenther's TRS-80 emulator, which grew from Tim Mann's xtrs, with a new layer underneath for the CMM2. All of sdltrs is there, its own menu included.

• The TRS-80 Model I, Model III, Model 4 and Model 4P.
• Floppy disks (JV1, JV3 and DMK images), hard disks, cassettes, the hi-res graphics boards, a joystick, a mouse and a serial port.
• Sound through the cassette port, as nearly all TRS-80 games make it, and the Model 4's sound port and the Orchestra 85 and 90.
• The Model 4's 80 x 24 screen fills MODE 8 (640 x 480) exactly. The 64 x 16 screen of the Models I and III is in the middle of it.
• It runs at the TRS-80's own speed with most of the processor to spare: about 85% on a Model I and 70% on a Model 4, on a Generation 1.
• What the TRS-80 writes to a disk goes into its file on the SD card, so your programs and files last.


What you need
No Tandy ROM comes with it: they are still copyright.

• The Model 4P needs no ROM at all. sdltrs has Peter Cervasio's free boot ROM built in, which starts a Model 4 system disk.
• LS-DOS 6.3.1 (Models 4 and 4P) and LDOS 5.3.1 (Models I and III) may be copied freely, by permission of their owner. Tim Mann keeps them at http://www.tim-mann.org/trs80.html as ld4-631.dsk, ld3-531.dsk and ld1-531.dsk.
• The Model I needs its Level II BASIC ROM as level2.rom, and the Models III and 4 the Model III ROM as model3.rom, in the folder. If you have a TRS-80 you can read its ROMs out; other TRS-80 emulators use the same files.
• If you do not have them, copies are at https://github.com/asig/xtrs-roms, to download and use at your own risk: level2rom.hex (the Model I) and romimage.m3 (the Model III). Copy them to A:/trs80 and rename them level2.rom and model3.rom; the emulator reads them as they are.


Getting started
Copy the trs80 folder of CMM2_Programs_7.00.00RC5.zip to A:/trs80, and put ld4-631.dsk in it. Then, with nothing of Tandy's at all:

CHDIR "A:/trs80"
RUN "trs80.app", -model 4p -disk0 ld4-631.dsk


With your own ROMs in the folder, this is enough:

RUN "trs80.app"


It starts the Model I if level2.rom is there, otherwise the Model III, otherwise the 4P. With no disk in the first drive it goes straight to ROM BASIC and READY. -model 1, -model 3, -model 4 and -model 4p choose the model, and -disk0 name.dsk to -disk7 put disks in the drives.


It answers the TRS-80's questions
A real TRS-80 asks questions every time it starts. The emulator answers them for you:

• MEMORY SIZE? (and Cass? on a Model III) is answered with Enter, which gives BASIC all the memory. -himem 32000 keeps the memory above that address free for machine code.
• Date and Time from LDOS and LS-DOS are answered from the CMM2's clock. LS-DOS 6.3.1 knows no year after 2011, so it is given the year 28 years earlier, whose calendar is the same day for day.
• -ask leaves them all for you, and the TRS-80 starts exactly as a real one does.


The keys
F7              sdltrs's menu: disks, cassettes, settings (Esc goes back)
F8              back to MMBasic, after asking (Ctrl+Alt+End at once)
F10             reset (Shift+F10 as from switching on)
F12             turbo
Esc             BREAK
Home, Delete    CLEAR
Arrows          the TRS-80's arrow keys


The other keys give what is printed on them, following OPTION USBKEYBOARD. To change disks, press F7, choose Floppy Disk Management and pick a file; then F10 to start from it.

One thing that is the TRS-80 and not a fault: a Model I types capitals without Shift, and Level II BASIC shows nothing else. Under LDOS, Shift with a letter gives lower case and Shift+0 swaps the two. It has no Caps Lock key.


Joystick and mouse
The first USB gamepad is the TRS-80's joystick (the Alpha Products one most games know): the d-pad or either stick moves it and a face button fires. The numeric keypad is the joystick as well. The mouse's right button opens the menu.


On a Generation 2
The MegaMem memory board (-megamem) works on a Generation 2 only, where the TRS-80 has its full 4MB. Everything else is the same on both.


What has been tried
On both generations: Level II BASIC, Model III BASIC, LDOS 5.3.1 on the Models I and III, LS-DOS 6.3.1 on the Model 4 and 4P, the menu, sound, and a USB keyboard, mouse and gamepad. On a Generation 1, a BASIC program saved to disk and loaded again in a later session.

Not tried yet: cassette files, /CMD files, hard disks, the hi-res boards, the printer, the serial port, saved states and games with a joystick. A disk cannot be write-protected from the menu. Reports are welcome.


More
Colour_Maximite_2_App_User_Guide.pdf, on the release page, has a chapter on it. sdltrs is under the BSD 2-Clause licence and xtrs under its own; the source is gitlab.com/jengun/sdltrs, with the CMM2's files in apps/trs80 of the firmware's repository.
 
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