You can check each address line at the ROM to see they are all being twiddled and that those connections are good. This is not fool proof as a bad bus latch or any chip on the address bus can much up one of more lines.
The data lines are more complicated. If you test at the ROM you will see them twiddling but you need to look at the ROM chip select at the same time to make sure you are seeing data from the ROM. Then you need to look for the same thing back at the processor to see if all the lines are good back to there. If you have more than 8 channels on your LA it will be much, much easier. As I recall I used channel 0 for the /WR had the Saelee software filter out all data there that bit was not low. Then I had to guess at what bit 0 might have actually been by looking at the disassembly. A lot of work but I learned a lot on the process. Good luck, Jeff Birt From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Eric Sent: Thursday, December 28, 2023 12:00 PM To: m...@bitchin100.com Subject: Re: [M100] Model 100 - LCD Shows Pixels Only Thank you everyone for the quick response! When I power up the computer, all pixels are on and remain dark (LCD is entirely "black"). Contrast potentiometer: Seems to work as intended. The display will lighten or darken as the potentiometer is adjusted. LCD PCB: No signs of corrosion and/or damaged traces. ROM: I'll ohm out the traces to see if I can find any broken connections. Otherwise, are there any other troubleshooting steps I can take? RAM: Jeff, great video! Thank you for sharing. The M100 Test Harness sounds like an ideal tool. I have limited experience with a logic analyzer however it looks like a fun challenge. I'll try to duplicate your setup but I may need some tips on how to configure the Saleae software... Eric On Thursday, December 28, 2023 at 08:17:02 AM PST, Josh Malone <josh.mal...@gmail.com <mailto:josh.mal...@gmail.com> > wrote:
