Difference between revisions of "VAXstation 100 firmware notes"
(ROM ver 5.00 versus 1983 spec.) |
(→Memory map: V5 difference from spec.) |
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==Memory map== | ==Memory map== | ||
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| + | Firmware 5.00 extends the LOOPBACK region to one more word at 4A0004. Apparently this loops back the value written to 480004. | ||
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[[Image:Vs100-memory-map.png]] | [[Image:Vs100-memory-map.png]] | ||
Revision as of 18:52, 17 February 2023
Random notes from running the firmware in an emulator.
The firmware analyzed announces itself as version 05.00. It deviates in minor details from the information in the 1983 "VS100 Engineering Specification".
Memory map
Firmware 5.00 extends the LOOPBACK region to one more word at 4A0004. Apparently this loops back the value written to 480004.
Error LEDs
Indicates which test failed. During power-up, green light turned off. During idle loop, green light remains on.
Apparently there's a bug.
Interrupts
All VS100 interrupts use the autovector feature.
Keyboard test
The firmware transmits code FD (hex) to the LK201 keyboard, which commands it to jump to the power-up sequence and self-test. The keyboard transmits a four-byte message back. The VS100 ignores the keyboard ID, and checks that the third is not 3D.
This information is from the VT220 Technical Manual.
D0 flags
The firmware maintains a set of flags in register D0.
| Bit (decimal) | Meaning |
| 16 | Manufacturing mode. |
| 17 | BBA present. |
| 18 | ? |
| 19 | Power-up error. |
| 20 | LEDs locked. |
| 22 | In maintenance menu. |
| 23 | Keyboard ok. |
| 24 | BBA done. |
| 25 | Vertical retrace interrupt. |
