exxos's Atari, Amiga & retro forum

I had no idea there were "fake" versions of the Pak 68/3 board.

Huh. Learn something new everyday. Glad I didn't get one, I had
enough trouble installing mine in my STacy, as is. :)

czietz wrote: 03 Mar 2021 16:34

czietz wrote: 16 Feb 2021 19:52 But there were unauthorized PAK68/3 ripoffs with faulty PCBs. [...] (And before you ask: No, I don't know how to tell them apart.)

PS: Now I know. Check connectivity between pin 14 of GAL U1 and pin 14 of GAL U2. The fake faulty PAK68/3 do not have connectivity between those two pins.

I have continuity between those pins so I guess I have a good PAK.

frank.lukas wrote: 12 Feb 2021 17:24 The circuit from a Mega ST is different to the 260/520ST in relation to the "DMA INT", "FDD INT" and "DRQ" ...

Try to change R102 from 4,7K to 1K

Hi Frank, sorry I took so long to respond. I now have my PAK68 machine set up again so I hope to get some progress on this issue. I can try to change R102 to 1K and I will report back to the thread. Do I still need to add the pullups on the floppy data lines? *Edit* Had to order the 1K resistor network so it will a couple of days to get here.

tuxie wrote: 15 Feb 2021 12:06 If you have floppy issues like this, then you have an Problem with BR/BG, try to meassure if there is a connection problem.. did you set the jumper correctly ? Are you using the PUK Gal? If yes, is all connected well?

Please try to explain your issue you have!

Hello, yes, I am using the PUK-A Gal and have J6 closed. Everything seems to be connected well. With regard to BR/BG, where should I measure these? I don't see them in my DMA/Floppy circuit.


My issue is that when I try to open Drive A from the desktop it reports


and when I try to open Drive C it reports:

Added the 10k resistor pull-ups but it didn't have any effect. Same thing is still happening.


*Edit* Some success! :D

SInce tuxie was mentioning BR being involved I removed the jumper for J6 BR and everything started working!


Oh course with no nvdi and referenced against a test with the blitter, the gembench seems a little low but that is why.

I don't understand why though it works. In the PAK manual it says this about J6


I assumed it had to be always closed since my PUK gal is not wired. Maybe someone can explain it to me so I understand.

And Gembench results are a little better with NVDI5 installed and the reference set to an STFM. :D

:bravo: :girldance:

Wait until you get it cranked up to 40/50mhz! (and throw in a matching FPU just
to make your GemBench page look really good. :)

BTW, I posted some pictures of my STacy's Pak 68/3 setup over at Atari Forum. No
sense in reposting them here but basically my J6 appears to be "open". I'm going to
assume that when the docs say "wired" they mean that I have the U3 slot filled with
P3 and a 68k chip in there, hooked up to switch back and forth between CPU's for
maximum compatibility.

It's been a long time since I actually had to work on my STacy so if the above has
nothing to do with your problem, never mind... :)

tuxie wrote: 08 Mar 2021 08:03 In the manual you can read! If the PUK gal is equipped then you have to remove it!!

As I said I had the same issue but without the PUK gal where I forgot the jumper to set!

The problem was I had mistranslated the section describing the conditions for J6 so I was going on a bad assumption.

So, yes, thank you for the suggestion that solved the problem!

I updated the English translation of the manual to correct the section on J6. It is over on the atari-forum if anyone wants to get it.