CP/M
Running CP/M on Timex/Sinclair hardware.
15 threads · 212 messages · 2008-01-31 → 2024-03-27
CP/M on Timex/Sinclair hardware is one of the longest-running threads in the community, and the list has converged on a clear picture of why it was always so hard and where it stands today. The 2068's memory map is the central obstacle: a 16K ROM and a video region inside the bottom 32K mean stock machines never had the contiguous 64K of plain RAM that standard CP/M 2.2 expects. Commercially, the only era-correct CP/M experience came via Timex Portugal's FDD3000, which is essentially a Z80 computer with its own RAM and floppies bolted onto the TS through a small interface ROM; Joao Encarnado and Gustavo Pane both used this path in the 1980s, and Portuguese and Polish users (plus Spectrum +3 owners) had CP/M routinely from early on, while US users almost never did.
The Yahoo-era discussions (2008) mostly debated whether CP/M was even worth chasing on a 2068 — Bill Loguidice and others noted that 40-column reformatted CP/M had worked on the C64 and Coleco Adam, and Emrah Oral floated the idea of putting CP/M on a DivIDE so it could exploit the 2068's hi-res 64/80-column modes. Nothing concrete shipped from that era, but it framed the requirements (contiguous RAM, a sensible disk path, a usable screen width) that the modern effort eventually had to solve.
The groups.io era turned the topic from speculation into archaeology and active engineering. David Anderson tracked down Clark Calkins, who in the early 1980s wrote his own Z80-optimized variant he called ZCP/M for the Exatron Stringy Floppy / A&J Microdrive on the TS1000, designed to sit in the 8–16K space; Clark joined a Zoom meeting in July 2023 and the group has been pushing to get that code released. They also surfaced the 1983 trip by Lon Hildreth (one of Will Stackhouse's colleagues) from Hartford to Digital Research in San Jose to pitch a Timex/Sinclair 2068 port of CP/M — David has the photocopied receipts in Lon's notebook, an artifact that anchors the long-rumored "Timex almost had official CP/M" story.
The most active current work is Eduardo Fuentes's RAM expansion board (started August 2023), which maps RAM into the full 0–64K range in 8K chunks — the ULA keeps using HOME RAM for the display, so the bank under the video region is freed for CP/M use; later iterations add port-7 bank switching for up to 560K. Gustavo Pane is writing a CP/M 2.2 compatible with the original Timex FDD disk format (40T SS/DD 160K and 80T DS/DD 640K, 16×256-byte sectors) using the Dock bank for TPA/CCP/BDOS/CBIOS and the Home bank as a CBIOS extension. In parallel, his 1985-vintage Pico/serial command vocabulary (descended from the same code he used to use his 2068 as a terminal to a CP/M host) is being folded into the TS-Pico, which Kevin and Ryan have been refining. Practical CP/M usage in the meantime is happening on Kaypros — Carl Miles brought one to the Albuquerque user-group meeting in February 2024 and discovered it only behaves on disk copies when clocked back down to 2.5 MHz.
Key threads
- Real CP/M on TS-2068 (#4074 on groups.io) — The active modern engineering thread: Eduardo Fuentes's RAM expansion board that maps RAM under the video region so the 2068 finally has the contiguous 64K CP/M needs, plus Gustavo Pane's CP/M 2.2 port targeting the original Timex FDD disk format. This is where the 40-year-old wish becomes a buildable project.
- Timex Connection video (#3880 on groups.io) — Mark Scheck spots Clark Calkins's comment online and the group realizes Clark wrote his own Z80-optimized CP/M variant (ZCP/M) for the Timex Stringy Floppy back in the early 80s. David emails him, he agrees to join a Zoom — the moment a piece of lost TS history walks back in the door.
- Clark Calkins' CP/M-Like OS; was: UPDATED! Timex/Sinclair User Group Meeting Monday July 3 (#3949 on groups.io) — Follow-up after Clark joined the July 2023 Zoom: Adam digs up Clark's 1988 Computer Journal article on his ZX81 ROM-based OS, and the group documents what ZCPM actually was vs. real CP/M — useful primary-source context for any future port.
- CP/M source available for the T/S2068?! (#3895 on groups.io) — Pushes on whether Clark's ZCPM code could be open-sourced (alongside the recently-public CP/M sources) and inventories the modern Z80 CP/M ecosystem (RC2014, RomWBW, Easy/Tiny Z80). Also includes Joao's clear explanation of how the FDD3000 actually delivered CP/M in the 80s via its own RAM and RS232 channels.
- 40 years ago this weekend (#4718 on groups.io) — David's scan of photocopied receipts from Lon Hildreth's November 1983 trip from Hartford to San Jose to meet with Digital Research about porting CP/M to the TS2068 — the concrete artifact behind the long-rumored 'Timex almost had official CP/M' story.
- Shorter TS Pico Commands (#6230 on groups.io) — Ties the 1985-era Gustavo Pane CP/M interface (originally used to make a 2068 talk to a CP/M host as terminal/storage) into the present-day TS-Pico command set. Shows the through-line from his original work to the active multifunction-interface project.
- Timex hi-resolution modes - CP/M (archive.org) — Yahoo-era (2008) discussion of whether CP/M on the 2068 makes sense at all — Bill Loguidice and others compare to 40-column CP/M on the C64 and Coleco Adam and weigh the 48K vs 64K problem. Frames the requirements the modern effort eventually had to satisfy.
- File Transfer Without Modems; was: Re: TS 2068 and Business? (archive.org) — Yahoo-era thread that drifts into Emrah Oral's DivIDE+CP/M-on-2068 proposal (msg 18) — the first time the group seriously floats putting CP/M on a modern storage interface and using the 2068's hi-res 64/80-column modes, an idea echoed in today's TS-Pico/FDD work.
All threads (15)
↳ marks a thread where this topic begins mid-conversation — the link jumps to the message where it starts.
| Thread | Msgs | Activity | Started by |
|---|---|---|---|
| ⭐ ABQ User Group Meeting - Sat. Feb. 3, 2024 📎 | 40 💬 | 2024-02-08 | Adam Trionfo |
| ⭐ Real CP/M on TS-2068 📎 | 34 💬 | 2024-03-27 | Eduardo Fuentes |
| ⭐ Timex hi-resolution modes - CP/M | 27 💬 | 2008-05-19 | M. Emrah Oral |
| ⭐ Shorter TS Pico Commands ↳ #6277 | 16 💬 | 2024-03-12 | Kevin |
| ⭐ CP/M source available for the T/S2068?! | 16 💬 | 2023-06-29 | kevin.personal |
| ⭐ What makes Z80 special? | 12 💬 | 2022-04-14 | Adam Trionfo |
| ⭐ Clark Calkins' CP/M-Like OS; was: UPDATED! Timex/Sinclair User Group Meeting Mon 📎 | 8 💬 | 2023-07-03 | Adam Trionfo |
| ⭐ Timex Connection video ↳ #3890 | 8 💬 | 2023-06-23 | David Anderson |
| Average age of group members | 26 💬 | 2008-01-31 | Bill Loguidice |
| Homemade TS2068 programs? ↳ | 11 💬 | 2008-06-24 | zxbruno |
| 2068 with micro drive on ebay ↳ #1269 | 9 💬 | 2022-04-18 | David Anderson |
| CP/M on the Timex or Atari? | 2 💬 | 2022-04-18 | Adam Trionfo |
| July 2022 CP/M Article with many Links | 1 💬 | 2023-07-06 | Adam Trionfo |
| 40 years ago this weekend 📎 | 1 💬 | 2023-11-05 | David Anderson |
| Off Topic CP/M Freebie | 1 💬 | 2022-01-26 | JEFFREY L BURRELL |