I created a new firmware for our beloved PicoCalc with pico2 board : PicoCalcTRS, a TRS-80 Model 3 Emulator.
It is based on the amazing work of @BlairLeduc for the Hardware Abstraction Layer.
It also use the core TRS-80 emulator SDLTRS.
Current firmware status and functionality:
Model III ROM boot works from SD and embedded fallback.
Disk drives :0 and :1 are integrated.
LDOS/TRSDOS/BASIC core workflows are working in current on-device tests.
The firmware artifact is PicoCalcTRS.uf2.
SD-card ROM lookup uses /TRS80/ROMS.
SD-card disk lookup uses /TRS80/DISKS.
Startup includes a disk file picker for attaching images to D0 and D1, including none.
Disk image filenames are not special-cased; the picker attaches whichever listed image the user selects.
PicoCalc Esc maps to TRS BREAK; PicoCalc BRK (Shift+Esc) maps to the TRS reset button.
The SDL timing shim uses Pico SDK time so the Z80 throttle path can target real Model III speed.
Standard Model III cassette-port game sound is wired to the PicoCalc PWM audio driver, with rate-limited updates for timing-heavy games such as SCARFMAN.
Optional PCM-backed disk motor/track SFX is available with F4; F5 mutes audio.
I’d love to use this, but I have only a Pico 1. (Though I am starting to consider buying a Pico 2W to replace it, given the number of projects here that seem to need it.)
That said, I also have an actual TRS-80 Model III motherboard (and working Model I), so there’s no huge hurry on this.
Back in the mid '80s, I had a Model I with two disk drives and an LP IV (Centronics 737) printer. I took this to a school that I went to at Fort Gordon, GA, in 1986. We had a deadly heat wave go through the region, and my wife was pregnant - so she went to her mother’s place half way through my schooling. I had my computer set up in the third bedroom (tiny mobile home, so tiny bedroom.)
I was using my computer for typing letters, short stories and other things. The word processor that I used was Michael Shrayer’s Electric Pencil. Well, I found it again:
This project has been quiet for about 6 months now. I wanted to play some Model III games, so I forked the repo and make some quick fixes/improvements. I just thought I could contribute and carry the torch a little further.
Fixes
No more display flicker. The screen redraws only the characters that changed, on the second core.
No more audio clicks at the end of each game sound or disk sound, and no pop at power-on.
The keyboard no longer stalls the emulator. Fast scrolling used to make it fall behind real time; it no longer does.
Model III special characters (codes 0xC0–0xFF: card suits, Greek letters, math and line-drawing symbols) now display correctly instead of as block graphics.
SD card reliability, from the updated picocalc-text-starter drivers: the firmware now waits properly for a busy card and skips deleted directory entries.
Improvements
Faster: the emulator now uses about 26% of the CPU, down from 38–86%. It runs from SRAM, and the LCD is drawn on the second core.
New font: 5×16 characters based on the Model III character ROM, on a white phosphor screen.
