TRS-80 PC-7 Troubleshooting Guide
.jpg)
No service manual for the TRS-80 PC-7 or its Casio original, the FX-5200P, is available from the Floodgap archive or the Internet Archive. What follows comes from Cameron Kaiser's description of the PC-7, the error-code list printed in its lid, and the PC-4 and PC-6 service manuals where a check carries over; those are marked.[1]
Symptoms
[edit | edit source]| Symptom | Probable cause | Action |
|---|---|---|
| Programs gone after a cell change | Normal: the PC-7 has no backup cell and nothing in memory survives the cells being removed | –[1] |
| No display | Flat cells or poor battery contact | Fit two fresh CR2032 cells; clean the cells and springs and lift the springs (the PC-6 manual's remedy)[2][3] |
| Letter keys dead or intermittent | Ribbon cable across the join strained or torn; membrane contacts | Check the join for cracks and the ribbon cable beneath it[1] |
| Single key dead | Key contact | Clean the contact pads and key rubber (the PC-6 manual's remedy for its similar keyboard)[3] |
| Missing dots or segments | LCD connection or LCD | The PC-7 uses the PC-4's LCD; the PC-4 manual lists the CPU, the LCD and the heat seal, in that order, for missing dots[1][4] |
| No way to save or print | Normal: the PC-7 has no expansion port | –[1] |
Memory check
[edit | edit source]A working PC-7 has 1,568 bytes free for programs with memory cleared.[1][2] Kaiser describes the extra 1 KB as Casio's OR-1 pack built onto the board, so a figure of 544 would mean that part of the memory is missing; the PC-4 service manual reads 544 the same way when its OR-1-equivalent module is not working.[1][4]
Error codes
[edit | edit source]The PC-7 reports errors by number. The list printed in its lid gives:[2]
| Code | Meaning |
|---|---|
| 1 | Memory overflow |
| 2 | Syntax error |
| 3 | Mathematical error |
| 4 | Undefined line number |
| 5 | Bad subscript |
| 6 | Variable error |
| 7 | Nesting error |
| 8 | Password error |
The PC-7's BASIC descends from that of the 1985 PC-4, which added password protection.[1]
Related pages
[edit | edit source]- TRS-80 PC-7
- TRS-80 PC-7 General Maintenance
- TRS-80 PC-7 Capacitor Replacement Guide
- TRS-80 PC-4 Troubleshooting Guide and TRS-80 PC-6 Troubleshooting Guide – the nearest documented relatives
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 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-7 section: one CPU, the PC-4's 12-character LCD, 2 KB with 1,568 bytes free, no battery backup, no expansion port, the membrane alphabetic keyboard, flex strain at the join and torn cases exposing the ribbon cable.
- ↑ 2.0 2.1 2.2 Pocket Museum, "The Tandy PC-7 computer (26-3673)". Retrieved 2026-10-21. Two CR2032 cells; 2 KB RAM with 1,568 bytes available; one line of 12 characters.
- ↑ 3.0 3.1 Tandy, Service Manual: Pocket Scientific Computer PC-6. Hosted as File:Tandy PC-6 Pocket Scientific Computer Service Manual (26-3672).pdf. Troubleshooting guide p. 10.
- ↑ 4.0 4.1 Radio Shack, Service Manual: TRS-80 PC-4 Pocket Computer and Cassette Interface. Hosted as File:Radio Shack TRS-80 PC-4 Pocket Computer and Cassette Interface Service Manual (26-3650).pdf. Troubleshooting, display, p. 8.