Phil M0OFXFeb 29, 2024

Good news on the #AnalogCable front: the Ghidra team have fixed a bug in the COFF loader. It can now load SysV (ISC) binaries!

I've been ripping into the ANIC utilities this evening. The ANICDownload utility (which boots the ANIC) has full symbols. Sadly the "LXTest" utility has been stripped...and seems to be written in Pascal! (it's full of Pascal strings)

Show threadPhil M0OFXFeb 29, 2024

This EPROM must be a maned wolf because it sticky its leggy out reeeeeaaallll far.

meme origin: https://www.etsy.com/listing/691910958/maned-wolf-leggy-vinyl-stickers

Maned Wolf Leggy Vinyl Stickers - Etsy

This Laptop Decals item by FelisRandomis has 537 favorites from Etsy shoppers. Ships from Manassas, VA. Listed on Dec 16, 2023

Show threadPhil M0OFXFeb 29, 2024
ANIC baseboard is being wired for probe
Show threadPhil M0OFXFeb 29, 2024
I wonder why the "With VisiTrigger" text isn't appearing. I probably need to copy an XCF font across.
Show threadPhil M0OFXFeb 29, 2024
Wired for probing
Show threadPhil M0OFXFeb 29, 2024
Good news, the ANIC is running code.
Show threadPhil M0OFX
Bad news, it's CALLing the RAM check, then doing a RET and landing in the weeds.
Someone at General Instrument didn't twig that you need to make sure the stack RAM works before you use CALL and RET.
Feb 29, 2024 at 3:35amWeb
Show threadPhil M0OFXFeb 29, 2024
wait no, it's doing a RET (1031766), landing at 0272 again (1031771), then doing another RET which underflows the stack?! what gives?!
Show threadPhil M0OFXFeb 29, 2024

I think I need two things: probing at the 286 so I can see the data going back and forth (to the RAM bus), and some kind of CPU status decoding so I can tell prefetch, memory r/w and I/O cycles apart on the analyser.
And it needs to work at 15MHz, or preferably 30. Groovy.

I could also do with a RAM test which doesn't use the stack and possibly prints status on the serial port.

Show threadPhil M0OFXFeb 29, 2024

Back on the #AnalogCable #ANIC repair tonight. I figured - this thing is a PC, right? The top board has a UART at COM1? Why not try Ruud's diagnostic ROM [1]?

Turns out Version 4.7, programmed into a 27C256, booted far enough to print out these checkpoint codes:
33 0 2 3 4 6 8 9 A t8A

Boot, port detect, video init (there isn't any). 0A is "detecting video RAM" (which is used for stack to test the main RAM) ... and 8A is "no video RAM, test halted".

Good start!

1: https://www.minuszerodegrees.net/ruuds_diagnostic_rom/clones/clones.htm

minuszerodegrees.net

Show threadPhil M0OFXMar 1, 2024
This is the second piece of General Instrument gear I've repaired which has been Varta'd.
Show threadPhil M0OFXMar 1, 2024
Retracked!
Show threadPhil M0OFXMar 1, 2024
Hopefully the old chip still works.
Show threadPhil M0OFXMar 1, 2024
It's alive! #AnalogCable
Also, someone asked if I could get some SCSI traces, so the SCSIView is out too.
Show threadPhil M0OFXMar 1, 2024
I don't think I've ever seen this thing boot with the ANIC interfaces online before!
Show threadPhil M0OFXMar 1, 2024
This looks like a command packet. 09 F9 would be a Reset Disconnect packet. Normally these are seven bytes long - this one is nine because it addresses three different cable boxes.
Show threadPhil M0OFXMar 1, 2024
RAM test looks healthier! At least it's jumping and returning okay.
Show threadPhil M0OFXMar 1, 2024
To be clear: that isn't the original battery, it's a new one. I'd normally fit a connector and mount the battery off-board, but I haven't found a better place to mount it without it being in a more risky place, or fouling something important.
Show threadvxoMar 1, 2024
@philpem vartablartablurrrrgghhhh
Show threaderazmus 🇨🇦Mar 1, 2024
@philpem I approve of Varta being used as a verb.