# PicoCalcTRS - TRS-80 Model 3 Emulator **URL:** \ **Category:** PicoCalc\ **Tags:** emulator, opensource, firmware\ **Created:** [April 28, 2026, 9:35am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215 "2026-04-28T09:35:58Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![JPCordeiro](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/jpcordeiro/32/16492_2.png) [@JPCordeiro](https://forum.clockworkpi.com/u/JPCordeiro)\ **Post date:** [April 28, 2026, 9:35am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/1 "2026-04-28T09:35:58Z")
Hi, 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. Firmware, source code and necessary files are here : [Releases · JeanPCordeiro/PicoCalcTRS · GitHub](https://github.com/JeanPCordeiro/PicoCalcTRS/releases) Feel free to play with it ! ---
**Author:** ![BlairLeduc](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/blairleduc/32/11808_2.png) [@BlairLeduc](https://forum.clockworkpi.com/u/BlairLeduc)\ **Post date:** [April 28, 2026, 10:32am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/2 "2026-04-28T10:32:16Z")
🤩 Thank you so very much for this ultra cool project! The Model III and I go way back. ---
**Author:** ![BrianO](https://avatars.discourse-cdn.com/v4/letter/b/f04885/32.png) [@BrianO](https://forum.clockworkpi.com/u/BrianO)\ **Post date:** [April 29, 2026, 2:56am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/3 "2026-04-29T02:56:23Z")
Is this for Pico 1 or Pico 2? ---
**Author:** ![JPCordeiro](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/jpcordeiro/32/16492_2.png) [@JPCordeiro](https://forum.clockworkpi.com/u/JPCordeiro)\ **Post date:** [April 29, 2026, 5:02am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/4 "2026-04-29T05:02:34Z")
Sorry, i dont precise : actually it’s for a pico 2. As soon as I can I try a build for pico 1 and leave news here ---
**Author:** ![BrianO](https://avatars.discourse-cdn.com/v4/letter/b/f04885/32.png) [@BrianO](https://forum.clockworkpi.com/u/BrianO)\ **Post date:** [April 29, 2026, 4:33pm UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/5 "2026-04-29T16:33:21Z")
Great! I have a Pico 2. I used to have a TRS-80 model 1. Looking forward to trying this firmware! ---
**Author:** ![cjs](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/cjs/32/16493_2.png) [@cjs](https://forum.clockworkpi.com/u/cjs)\ **Post date:** [April 30, 2026, 5:46am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/6 "2026-04-30T05:46:30Z")
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. 🙂 ---
**Author:** ![granzeier](https://avatars.discourse-cdn.com/v4/letter/g/cab0a1/32.png) [@granzeier](https://forum.clockworkpi.com/u/granzeier)\ **Post date:** [May 13, 2026, 10:24am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/7 "2026-05-13T10:24:56Z")
I’ve got it: ![PicoCalc TRSDOS](https://canada1.discourse-cdn.com/flex029/uploads/clockworkpi/original/3X/e/8/e8c798c411bd9b19388feae01230c41dedfc464a.jpeg) ![PicoCalc LDOS](https://canada1.discourse-cdn.com/flex029/uploads/clockworkpi/original/3X/b/c/bc9cb2991c077ec0b56ae196e3224d353341d929.jpeg) Works well, and lots of fun. Thank you. ---
**Author:** ![granzeier](https://avatars.discourse-cdn.com/v4/letter/g/cab0a1/32.png) [@granzeier](https://forum.clockworkpi.com/u/granzeier)\ **Post date:** [May 13, 2026, 7:35pm UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/8 "2026-05-13T19:35:54Z")
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: ![PicoCalc Pencil 1](https://canada1.discourse-cdn.com/flex029/uploads/clockworkpi/original/3X/c/1/c1f843147c7dfe04c44067ec525861cd39bb56e8.jpeg) The .DSK file (on a bootable TRSDOS disk) is here: [http://cpmarchives.classiccmp.org/trs80/Software/Model%20III/Electric%20Pencil%20v2.0z%20(1981)(Michael%20Shrayer)[DSK].zip](http://cpmarchives.classiccmp.org/trs80/Software/Model%20III/Electric%20Pencil%20v2.0z%20(1981)(Michael%20Shrayer)%5BDSK%5D.zip) The file is in the CPM Archives at: [\home\nathanael\DiskStation\web\cpm\trs80\Software](http://cpmarchives.classiccmp.org/trs80/Software/index_DirHTML.html#IDModel_III) (tagged to the TRS-80 Model 3 collection. Very cool, Jean, thanks again for my “new” TRS-80 Model III (although I’ve had a few Model Is, I never got a Model III, until now.)😉 ---
**Author:** ![JPCordeiro](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/jpcordeiro/32/16492_2.png) [@JPCordeiro](https://forum.clockworkpi.com/u/JPCordeiro)\ **Post date:** [May 29, 2026, 9:37am UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/9 "2026-05-29T09:37:59Z")
Very happy that this little project pleased you ! I’m now working on an Oric-1/Atmos emulator 😉 ---
**Author:** ![BlairLeduc](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/blairleduc/32/11808_2.png) [@BlairLeduc](https://forum.clockworkpi.com/u/BlairLeduc)\ **Post date:** [October 21, 2026, 8:23pm UTC](https://forum.clockworkpi.com/t/picocalctrs-trs-80-model-3-emulator/22215/10 "2026-10-21T20:23:49Z")
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. * * * > **[Release v0.2 · BlairLeduc/PicoCalcTRS](https://github.com/BlairLeduc/PicoCalcTRS/releases/tag/v0.2)** > > TRS-80 Model III emulator firmware for the ClockworkPi PicoCalc (RP2350). Copy PicoCalcTRS.uf2 to the Pico in BOOTSEL mode. > Fixes > > No more display flicker. The screen redraws only the characters th...