VAXstation 100 firmware notes
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Revision as of 15:59, 15 February 2023 by Larsbrinkhoff (talk | contribs) (→D0 flags: BBA present.)
Random notes from running the firmware in an emulator.
Memory map
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. |
| 19 | Power-up error. |
| 24 | BBA done. |
| 25 | Vertical retrace interrupt. |
