05-05-2022, 10:55 AM
Hi Thags.
The fact that you get some video out [garbled or otherwise] means that the processor is executing the boot rom to a certain extent.
I say this because to get any video out, the video controller (6545 CRT controller) has to be programmed which happens while executing
the boot rom code.
It looks to me to be some problem with accessing the video ram (screen character ram, colour ram, attribute ram).
Have you checked your 256TC to see that the NiCad battery has been removed & that there is no PCB damage from leakage?
The fact that you get some video out [garbled or otherwise] means that the processor is executing the boot rom to a certain extent.
I say this because to get any video out, the video controller (6545 CRT controller) has to be programmed which happens while executing
the boot rom code.
It looks to me to be some problem with accessing the video ram (screen character ram, colour ram, attribute ram).
Have you checked your 256TC to see that the NiCad battery has been removed & that there is no PCB damage from leakage?