IBM 5120 Troubleshooting Guide: Difference between revisions
Deep technical pre-PC IBM page with verified sources (Bitsavers MIM/MAP, Wikipedia, IBM Archives) — honest gap disclosure where IBM did not publish per-board cap values |
Expand troubleshooting: RS/6000 LED codes+NVRAM battery / 51xx PALM+PSU rails+tape/floppy; cited (Kev009/voidstar/Bitsavers) |
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# If diskette won't load, check drive belt, head, alignment. | # If diskette won't load, check drive belt, head, alignment. | ||
# Cross-reference any check-stop code against MIM SY34-0192 and Logic Manual SY34-0193. | # Cross-reference any check-stop code against MIM SY34-0192 and Logic Manual SY34-0193. | ||
== Architecture == | |||
The IBM 5120 is built around the IBM '''PALM''' (Program All Logic in Microcode) 16-bit processor, with its operating environment (APL and/or BASIC) held in microcode "read-only storage" (ROS). It is not PC-compatible and predates the IBM PC, so PC diagnostics do not apply — use the routines in the IBM Maintenance Information manual.<ref name="ibm51">[https://voidstar.blog/ibm-5100-power-supply/ IBM 5100 Power Supply], voidstar; [https://en.wikipedia.org/wiki/IBM_PALM_processor IBM PALM processor], Wikipedia; and the IBM 5110/5120 Maintenance Information manuals on [https://bitsavers.org/pdf/ibm/ Bitsavers]. Source for the PALM architecture, the five-rail PSU, and the 5120 dual power supplies.</ref> | |||
== Power supply == | |||
This machine has '''two power supplies''' — one for its pair of disk drives and a second identical to the 5100/5110 supply. Confirm every rail (the 5100/5110-type supply produces '''+12 V, −12 V, +8.5 V, +5.0 V and −5.0 V''') before chasing logic faults. Ageing electrolytics are the usual failure — recap and re-check the rails.<ref name="ibm51">[https://voidstar.blog/ibm-5100-power-supply/ IBM 5100 Power Supply], voidstar; [https://en.wikipedia.org/wiki/IBM_PALM_processor IBM PALM processor], Wikipedia; and the IBM 5110/5120 Maintenance Information manuals on [https://bitsavers.org/pdf/ibm/ Bitsavers]. Source for the PALM architecture, the five-rail PSU, and the 5120 dual power supplies.</ref> | |||
== Storage and display == | |||
The 5120 uses a pair of '''8-inch floppy''' drives and a 12-inch CRT. Mechanisms need cleaning and belt/roller service; the IBM Maintenance Information manuals (on Bitsavers) give the full disassembly, adjustment and diagnostic procedures.<ref name="ibm51">[https://voidstar.blog/ibm-5100-power-supply/ IBM 5100 Power Supply], voidstar; [https://en.wikipedia.org/wiki/IBM_PALM_processor IBM PALM processor], Wikipedia; and the IBM 5110/5120 Maintenance Information manuals on [https://bitsavers.org/pdf/ibm/ Bitsavers]. Source for the PALM architecture, the five-rail PSU, and the 5120 dual power supplies.</ref> | |||
== References == | |||
<references /> | |||
== Related Pages == | == Related Pages == | ||