exxos's Atari, Amiga & retro forum

You could try a higher value in series with pin 38 I think it was... 500R or even 1k.. Not much else to try really..

http://www.exxosforum.co.uk/atari/last/g ... /index.htm

Maybe some food for thought...

exxos wrote: 08 Oct 2018 22:03

It only seems to say is driven with a open collector, but does not really say is needed for any reason..

It needs to be open collector as there can be multiple DMA devices driving it.

rpineau wrote: 09 Oct 2018 02:23 It needs to be open collector as there can be multiple DMA devices driving it.

But there isn't, only Hard Drive port..

Oh yes. my mistake, I was thinking of it as an output :) .. but it's an input from DMA port to DMA via the gate so the gate output is connected to only one device .. the DMA chip.

exxos wrote: 09 Oct 2018 00:44 You could try a higher value in series with pin 38 I think it was... 500R or even 1k.. Not much else to try really..

Tried 500R and it doesn't see drives at all just stuck on white screen

Icky wrote: 09 Oct 2018 22:21 Tried 500R and it doesn't see drives at all just stuck on white screen

Odd.. so another odd dma issue to look into then... see how things go with the new LS chip first though.. maybe its the delay which makes the magic..

exxos wrote: 09 Oct 2018 22:23

Icky wrote: 09 Oct 2018 22:21 Tried 500R and it doesn't see drives at all just stuck on white screen

Odd.. so another odd dma issue to look into then... see how things go with the new LS chip first though.. maybe its the delay which makes the magic..

Just got the chips today. Starting to take a look now.

Icky wrote: 09 Oct 2018 22:24

exxos wrote: 09 Oct 2018 22:23

Odd.. so another odd dma issue to look into then... see how things go with the new LS chip first though.. maybe its the delay which makes the magic..

Just got the chips today. Starting to take a look now.

Placed LS06 with pull-ups in U51

Still floppy not found when HDD connected

I think I am getting somewhere I think there is still some issues in the layout round the DMA, MFP and WD1772.

On STF remake schematic U32B pin 5 is marked as going to INTR but on the board this actually goes to a pull-up RP1 only.


Checking the STFM original schematic U32B pin 5 should go to pin 28 the INT on the WD1772 and on the STF Remake its marked as INTRQ

However pin 28 on the WD1772 on the STF remake is not connected to any INT but is connected to one of planes.


I did a patch by lifting pin 28 on WD1772 and lifting pin 5 on U32 and soldering wire between them.

Floppy drive still works but when HDD is connected there is just a white screen

Still going round the circuit for other problems that might be there