Gary C
Veteran Member
Well, finally got around to powering up my TC01 last night.
Whirred and clicked and displayed a steady display but with a white box on the right and corrupt text on the left.
Typing commands caused the drive to read and the display changes, but still corrupt.
This computer uses a Texas Instruments video processor called a TMS9129 which uses its own ram to store the display. This unit allows multiple overlays to display sprites and graphics. Given the CPU is running, I suspect either the VPU or the VRAM. Hooking up the logic analyser shows all signals such as RAS/CAS, address and data lines operating but its hard to tell much more than that. Its possible its being told to display junk I suppose.
Anyway, got some TMS4416 rams on order, and have even managed to find a couple of TMS9129 processors as well (fakes ? maybe, only time will tell) so will remove and socket them to aid diagnosis so I can swap chips and see any changes (with three VPU's, it would be a pain to keep unsoldering them)
Will I remove the sockets after repair ? maybe.
Whirred and clicked and displayed a steady display but with a white box on the right and corrupt text on the left.
Typing commands caused the drive to read and the display changes, but still corrupt.
This computer uses a Texas Instruments video processor called a TMS9129 which uses its own ram to store the display. This unit allows multiple overlays to display sprites and graphics. Given the CPU is running, I suspect either the VPU or the VRAM. Hooking up the logic analyser shows all signals such as RAS/CAS, address and data lines operating but its hard to tell much more than that. Its possible its being told to display junk I suppose.
Anyway, got some TMS4416 rams on order, and have even managed to find a couple of TMS9129 processors as well (fakes ? maybe, only time will tell) so will remove and socket them to aid diagnosis so I can swap chips and see any changes (with three VPU's, it would be a pain to keep unsoldering them)
Will I remove the sockets after repair ? maybe.