IBM PC (5150) Troubleshooting Guide: Difference between revisions
Create symptom-driven troubleshooting guide: POST beep codes, parity errors, bank-0 RAM failure, keyboard 301, video/MDA/CGA, V20 swap notes, and 8088 interrupt bug. |
Clean up red links: create supporting pages for relevant items, unlink tangential ones (IBM 5100, Datamaster, NEC V20, Soarer's Converter, DIP switch reference, Memtest86, Model F foam pad replacement) |
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* Reseat the DIN-5 connector. | * Reseat the DIN-5 connector. | ||
* Swap to a known-good Model F. If the suspect keyboard works on another 5150 or XT, the 5150's keyboard interface is at fault — check U36 (8255 PPI) and the 7406 keyboard data buffer. | * Swap to a known-good Model F. If the suspect keyboard works on another 5150 or XT, the 5150's keyboard interface is at fault — check U36 (8255 PPI) and the 7406 keyboard data buffer. | ||
* '''Model F variants''': the 83-key XT-style Model F works on the 5150 and 5160. The 84-key AT-style Model F and the 101-key Model M will '''not''' work without a | * '''Model F variants''': the 83-key XT-style Model F works on the 5150 and 5160. The 84-key AT-style Model F and the 101-key Model M will '''not''' work without a protocol converter. | ||
=== Cassette port silence === | === Cassette port silence === | ||
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=== V20 CPU issues === | === V20 CPU issues === | ||
Swapping the 8088 for an | Swapping the 8088 for an NEC V20 gives a 20-30% speed boost on most code, but the V20 emulates an 80186-class instruction set that breaks a small number of programs. If a known-good machine suddenly fails to run an old game or compiler after a V20 swap, drop the original 8088 back in to confirm. | ||
=== Interrupt bug in early 8088s === | === Interrupt bug in early 8088s === | ||