exxos's Atari, Amiga & retro forum

Great progress! See my offer to use EmuTOS for debugging the hardware.

Icky wrote: 22 Sep 2018 09:22 Just thought I would share what the board looks like when booting with the diagnostic cart.
Showing the E7 Spurious Interrupt message and a few graphical glitches

Thanks. Looks like some small ram corruption going on there..

DiagROM posted out this morning, Assume should get them Monday.

exxos wrote: 22 Sep 2018 12:16 DiagROM posted out this morning, Assume should get them Monday.

Thanks Exxos

Out of interest, what happens if you try to boot without the RAM card installed ?

exxos wrote: 22 Sep 2018 16:22 Out of interest, what happens if you try to boot without the RAM card installed ?

Great minds think a like. I have done such a test this morning.

With the RAM board off and no Diag Cart the screen is black with white border

With the RAM board off and with the Diag Cart plugged in the screen is white with red border

Icky wrote: 22 Sep 2018 16:41 With the RAM board off and no Diag Cart the screen is black with white border

With the RAM board off and with the Diag Cart plugged in the screen is white with red border

So it must be accessing RAM to a point. Though looking at the corruption lines, kinda look like 8 bits of corruption. Still kinda half think there is a bus conflict somewhere corrupting the bus causing those IRQ errors.. I've only seen the ACIA's causing that kind of conflict and error so far though. Disabling the ACIA would stop the conflict, But we tried that already.. unless E clock has to be held as well and CS isn't enough..

EDIT:
Did actually make a note of all this somewhere.. Think E is "output enable" so have to check on the data sheet if high or low disables it, thats the important thing to stop it conflicting on the bus.

exxos wrote: 22 Sep 2018 17:17 So it must be accessing RAM to a point. Though looking at the corruption lines, kinda look like 8 bits of corruption. Still kinda half think there is a bus conflict somewhere corrupting the bus causing those IRQ errors.. I've only seen the ACIA's causing that kind of conflict and error so far though. Disabling the ACIA would stop the conflict, But we tried that already.. unless E clock has to be held as well and CS isn't enough..

EDIT:
Did actually make a note of all this somewhere.. Think E is "output enable" so have to check on the data sheet if high or low disables it, thats the important thing to stop it conflicting on the bus.

Thanks Exxos - I am soaking up this info like a sponge. I have started to read more about these ACIA's to understand what they do. :)

In addition I have modified one of my Hi-Res cables to work on the STF board pinout and I did not need to put the buffer circuit in you suggested in another thread. It just fired up. Thus I won't be adding the buffer for now.


There is a bit more of a pattern here when I watch this in Hi-Res. I am starting to wonder if that pattern I see creeping across the screen is it trying to draw more bombs but due to the distortion its just lines.

I'll get a video together of the boot in Hi-Res

cool :)

Yeah, I'm not at home to be much help.. but the ACIA docs should tell you how to disable the ACIA totally, then just hardwire it.. probably CS & E need to be set to disable the ACIA.. its what I did on my SEC booster but in code.. keyboard wont work of course, but will help to see if ACIA are causing issues or not at least.

I found my post on the ACIA https://www.exxosforum.co.uk/forum/viewt ... =150#p6255

Looks like E has to be low to disable the ACIA. So if you lift those 2 pins and connect to 0V, then it should rule out ACIA bus conflicts...

Do you do this with both 6850?