IBM PS2 Model 50 Schematics
The PS/2 Model 50 schematic set is a 16-page PDF of third-party logic drawings of the PS/2 Model 50 (8550) system board. The title blocks read "Maintenance Information Technology", "PS/2 50" and "COPYRIGHT APPLIED FOR"; the notice beside them names Maintenance Information Technologies, says the content was sold for the buyer's unlimited use and must not be copied for republication or distribution outside the buyer's company, and gives no warranty of accuracy. All sheets present are revision 4, dated between 21 May and 2 June 1991. The scan is image-only.
PDF page 1 is a placeholder reading "Sheet 1 Missing from Original Set", so the drawings run from sheet 2 to sheet 16.
Contents
| Sheet | Title | Sheet | Title |
|---|---|---|---|
| 2 | CPU | 10 | Disk I/F |
| 3 | Memory | 11 | Real Time Clock |
| 4 | Clocks | 12 | DMA I/F |
| 5 | Bus Connections | 13 | Video I/F |
| 6 | Serial I/O | 14 | Bus Connectors/B |
| 7 | Interrupts | 15 | I/O Control |
| 8 | Keyboard I/F | 16 | Bus Controller |
| 9 | Printer I/O |
The drawings carry designators and values for the parts on each circuit. Sheet 11 shows the real-time clock ZM47, a Motorola MC146818A, with its oscillator (Y1 32.768 kHz, C17 27 pF, R16 2 MΩ and 14069 inverters ZM28A-C), the standby supply through diodes CR1 to CR6 with R10 620 Ω from +12 V, R12 1 kΩ to CKFS, R9 10 kΩ and C16 0.0056 µF on RESET. The same sheet has ZM50, a 74ALS244 that puts the diskette status lines on XD0-XD7, and an electrolytic, C8 22 µF 25 V.
What this document does not contain
Sheet 1 is missing. There is no parts list, bill of materials, board layout or power-distribution sheet, so the set is not a complete capacitor list, and it does not say which board revision (Type 1 or Type 2) it was drawn from.
Pages that cite this document
- IBM PS/2 Model 50 lists it as the planar schematics.
- IBM PS2 Model 50 Technical Reference (May 1988), IBM PS2 Model 50 Technical Reference (October 1990), IBM PS2 Model 50 Hardware Maintenance Reference, IBM PS2 Model 30 Schematics and IBM PS2 Model 80 Schematics list it as related.
Download: IBM PS2 Model 50 Schematics.pdf