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Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 05 Feb 2024 14:35
by BeigeFM
All the chips look to be the same. I can't see which would be a parity chip.
https://ibb.co/w0kntZJ
I did check some posts on this forum but users can't seem to agree on removing the chip or if parity makes a difference.
I'd be willing to give it a go and remove a chip from the end... I can always solder it back. I hope!
Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 05 Feb 2024 18:54
by BeigeFM
Wow. Done nothing but read all afternoon about 30pin and 72pin Simms. Brought some of my own memories back!
I'm still confused about grounding this parity bit, or removing a SIM.
I'm not seeing much online other than a pin out for 30pin Simms showing pin 27 and 29 (I think) or which chip to remove
Would appreciate any advice on that.
It's not a deal killer for me. I could always sell the unspoiled rams on eBay and recover some cash for purchasing non parity Simms.
Draper soldering iron has arrived this morning along with a few other bits! Let the fun begin!
Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 06 Feb 2024 20:31
by BeigeFM
So I've done some more work on the Atari essentially the mandatory fixes including adding 8 10k resistors to the chip at the back.
I can now run the bad apple demo and it doesn't bomb! So I thought " Yes, I've nailed it! "
I do occasionally see graphics glitches however. Played exolon and kid gloves 2.
I'm wondering now if parity ram is the problem.
Memory tests out ok on ram test and 2.06 TOS.
I can't think what else it could be.
I'll drop some screenshots in tomorrow when I get a minute.
Has anyone else had graphical glitches due to parity ram? They are very minor.
Thanks in advance.
Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 06 Feb 2024 21:17
by rubber_jonnie
BeigeFM wrote: 06 Feb 2024 20:31
So I've done some more work on the Atari essentially the mandatory fixes including adding 8 10k resistors to the chip at the back.
I can now run the bad apple demo and it doesn't bomb! So I thought " Yes, I've nailed it! "
I do occasionally see graphics glitches however. Played exolon and kid gloves 2.
I'm wondering now if parity ram is the problem.
Memory tests out ok on ram test and 2.06 TOS.
I can't think what else it could be.
I'll drop some screenshots in tomorrow when I get a minute.
Has anyone else had graphical glitches due to parity ram? They are very minor.
Thanks in advance.
Overall parity RAM is not recommended as your mileage may vary. I would suggest you may want to swap out for non-parity.
I have heard folks say they have no issues with it, but I couldn't get any of my own STE's to run reliably with parity RAM. It would either fail the bootup RAM test, any RAM test software, or appear to work and fail when running some software or other.
Have a look here:
Parity RAM fail
Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 01 Mar 2024 21:23
by BeigeFM
Thanks Rubber Johnny you was right and I forgot to give you credit ! I did also read a post on another forum by Simbo from 2011.
Today I decided what the heck and removed chip 9 from my parity ram. This was based on some limited posts by someone called Simbo on another Atari forum and a little bit of web searching.
(And being pointed in that direction by RubberJohny.
This has absolutely solved my stability issues and the desktop is faster to boot, quicker to open windows etc.
At the moment I'm recovering with some relief as I had to repair two sticks because I had desoldered the capacitor under the chip. I had to put it back! Now all the games work on my SD4ST which I could only get 1 out of every four games working. I'm currently very pleased.
Just to add. I couldn't understand why my STE was so slow. I thought it was rose tinted specs from 35 years ago. Clearly it was the Ram all along.
Thanks again for your support! Appreciate it very much!
Re: Unsure if hardware issue with DMA, something else or nothing wrong
Posted: 01 Mar 2024 23:27
by rubber_jonnie
BeigeFM wrote: 01 Mar 2024 21:23
Thanks Rubber Johnny you was right and I forgot to give you credit ! I did also read a post on another forum by Simbo from 2011.
Today I decided what the heck and removed chip 9 from my parity ram. This was based on some limited posts by someone called Simbo on another Atari forum and a little bit of web searching.
(And being pointed in that direction by RubberJohny.
This has absolutely solved my stability issues and the desktop is faster to boot, quicker to open windows etc.
At the moment I'm recovering with some relief as I had to repair two sticks because I had desoldered the capacitor under the chip. I had to put it back! Now all the games work on my SD4ST which I could only get 1 out of every four games working. I'm currently very pleased.
Just to add. I couldn't understand why my STE was so slow. I thought it was rose tinted specs from 35 years ago. Clearly it was the Ram all along.
Thanks again for your support! Appreciate it very much!
Sorry, I seem to have lost track with this thread, glad I could help and your machine is running properly :)