exxos's Atari, Amiga & retro forum

DoG wrote: 06 May 2020 20:22 Lots of schematics and other stuff can be found at https://docs.dev-docs.org/

Thanks for this gold mine.

Hi
I have just received the MMU and GLUE sold by Exxos.
Unfortunatly my old STF has always its full white screen. :|
Could it be the TOS ROM ?

It certainly could be, if RAM is bad you get a white border and black background an sometimes corruption, ROM can easily cause the symptoms you see. First check 5v and GND are good to all ROM chips. If you have a spare set, you can try them but make sure you correctly align them as you can kill ROMs by plugging them in the wrong way round.

I'd suggest a logic probe to test the address and data lines when powered on, but you can test for continuity with a multimeter.

Make sure you have continuity from the MMU to the address and data lines back to the CPU.

My STF is alive !!!! :yay2:

After changing GLUE and MMU without success I've replaced TOS 1.0 chip by TOS 1.04. And the ST is running.
To check I reinstalled previous GLUE and MMU and it works too. So the pb was "simply" the TOS old chip.

However the result is not completly good. I have always the vertical lines in the color mode. In the hi res mode it is better.
Any idea ?

San-A