Hi Jeff,
Luckily my logic analyzer does have more than 8 channels.
Can you give me some feedback on these settings:
Chip M2 TC40H245P - Octal Bi-Directional Bus Buffer
Simple Parallel DecoderSample Rate: 6.25 MS/s or 10 MS/s?Clock State: Rising
EdgeVoltage: 1.2 Volts, 1.8 Volts, or 3.3 Volts?Stop recording after 2 seconds
Eric
On Thursday, December 28, 2023 at 10:53:55 AM PST, <[email protected]>
wrote:
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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 <[email protected]> On Behalf Of Eric
Sent: Thursday, December 28, 2023 12:00 PM
To: [email protected]
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
<[email protected]> wrote:
