TRS-80 PC-5
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| Tandy PC-5, opened out (photograph Pocket Museum) | |
| Specifications | |
|---|---|
| Manufacturer | Casio, for Radio Shack (Tandy Corporation) |
| Type | Pocket computer |
| Released | 1985 |
| Intro price | US$119.95 |
| CPU | Two HD61747 CMOS processors (HD61747B10 and HD61747B11) |
| Memory | 4 KB, 3,552 bytes free for programs |
| Storage | Cassette, through the 26-3651 interface and 26-3671 link cable |
| Display | 24-character LCD |
| Sound | — |
| Power | Two CR2032 lithium cells; one CR1220 for memory backup |
| Dimensions | 142 × 71 × 18 mm closed; 142 × 142 × 9 mm open |
| Weight | 161 g with batteries |
| OS / Firmware | BASIC, CAP-X assembler |
| Successor | TRS-80 PC-6 |
| Model no. | 26-3670 |
The TRS-80 PC-5, sold as the Tandy Pocket Scientific Computer PC-5, catalogue number 26-3670, is a clamshell pocket computer that Tandy introduced in 1985. It is a rebadged Casio FX-780P, the 4 KB model of the case and design that became the TRS-80 PC-6.[1][2] It has two HD61747 processors, a 24-character LCD in the lid, a membrane keyboard for the letters, and two CR2032 cells with a CR1220 to keep the memory.[1][2]
History
[edit | edit source]The PC-5 and PC-6 were the first Tandy pocket computers sold as "Pocket Scientific Computers", for their advanced mathematics and statistics functions. Both cost US$119.95. The PC-5 lasted less than a year before the 8 KB PC-6 replaced it, and Kaiser describes it as considerably harder to find today.[1] Its BASIC grew from the 1985 version of the TRS-80 PC-4, and like the PC-6 it has a Data Bank for simple records and a CAP-X assembler.[1]
Telling a PC-5 from a PC-6
[edit | edit source]The two share a case, and Kaiser gives three ways to tell them apart: the label, the RESET button on the front of the PC-6 only, and the memo key, which is marked MEMO on the PC-5 and MEMO (SEARCH) on the PC-6.[1] The photograph in the infobox shows a PC-5 with no RESET button below the power switch and a plain MEMO key.
| PC-5 (26-3670) | PC-6 (26-3672) | |
|---|---|---|
| Casio original | FX-780P | FX-790P |
| Introduced | 1985 | 1986 |
| Processors | HD61747B10, HD61747B11 | HD61747B20, HD61747B25 |
| Memory | 4,096 bytes, 3,552 free | 8,192 bytes, 7,520 free |
| RAM expansion | Slot present but covered by a sticker | 26-3674 (8 KB) |
| RESET button | No | Yes |
| Memo key | MEMO | MEMO (SEARCH) |
The PC-5 has a memory expansion slot, covered inside by a plastic sticker; Kaiser is not sure the PC-5 would use a pack if one were fitted.[1]
Power
[edit | edit source]The PC-5 runs from two CR2032 lithium cells, with a CR1220 holding the memory while they are changed.[2] Kaiser notes that the PC-5 and PC-6 are the only Tandy pocket computers with this backup cell.[1] Without a PC-5 manual Tandy's rated cell life for it is not known; the PC-6 service manual's figures for the PC-6 are on the TRS-80 PC-6 page.
Options
[edit | edit source]The PC-5 uses the PC-4's 26-3651 cassette interface and 26-3652 printer through the 26-3671 link cable (Casio SB-2).[1][2]
Known problems
[edit | edit source]Kaiser reports that most PC-5 and PC-6 units on the second-hand market have broken hinges or latches. The letter keys are on a membrane panel that he describes as mushy.[1] A 3D-printed replacement latch for the PC-5 and PC-6 has been published; see TRS-80 PC-5 General Maintenance.
Documentation
[edit | edit source]Neither the Floodgap archive nor the Internet Archive holds a Tandy service manual or owner's manual for the PC-5. The Floodgap archive points PC-5 owners to the PC-6 service manual, which Kaiser says generally applies to the PC-5; it is described at TRS-80 PC-6 Documentation.[1][3]
Repair guides
[edit | edit source]- TRS-80 PC-5 General Maintenance – cells, hinges and latch, keyboard
- TRS-80 PC-5 Troubleshooting Guide – faults, and how far the PC-6 manual applies
- TRS-80 PC-5 Capacitor Replacement Guide – what is known of the electrolytics
Related pages
[edit | edit source]- TRS-80 Pocket Computer – the whole Tandy pocket computer line
- TRS-80 PC-6 – the 8 KB successor in the same case
- TRS-80 PC-4 – the model whose cassette interface and printer the PC-5 uses
- Battery Explosion, Capacitor or Corrosion Damage
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Cameron Kaiser, "Tandy Radio Shack Pocket Computer PC-4 and Tandy Pocket Scientific Computer PC-5, PC-6, PC-7", Floodgap Retrobits, Tandy! Pocket! Mania!. Retrieved 2026-10-21. PC-5 and PC-6 section: the PC-5 (26-3670) introduced in 1985 as the Casio FX-780P with HD61747B10/B11 processors and 3,552 of 4,096 bytes free; folded and open sizes; the two-CPU design; the backup battery; the membrane keyboard; broken hinges and latches; the PC-5's memory expansion slot covered by a plastic sticker; the RESET button and MEMO (SEARCH) key found only on the PC-6; both models at US$119.95; the PC-5 replaced within a year and now harder to find; options 26-3671; the PC-6 service manual generally applying to the PC-5.
- ↑ 2.0 2.1 2.2 2.3 Pocket Museum, "The Tandy PC-5 computer (26-3670)" and "The Casio FX-780P computer". Retrieved 2026-10-21. Specification table: 4 KB RAM, 3,552 bytes available, one line of 24 characters, dual-tone beep, 142 × 142 × 9 mm opened, 161 g with batteries, two CR2032 and one CR1220 lithium batteries; options 26-3652 and 26-3651.
- ↑ Cameron Kaiser, Floodgap Retrobits, Tandy TRS-80 Pocket Computer Archive, gopher://gopher.floodgap.com:70/1/archive/tandy-pocket-computer-archive/manuals. Retrieved 2026-10-21. The archive's note that it lacks PC-5 documentation and that the PC-6 manual should be used.