PAK issues

[DoG]

Not trying to steal the tread but is there something else besides the ST-MK48S74 you can use in PAK68/3? Or where to find 2 of these. 20Ns also... puh!

[Atarian Computing]

IDT71B74S20Y with soj adapter or I believe MK48S80 will work as well?

[PhilC]

20190127_175525.jpg

20190127_175538.jpg

J1 off
J2 off
J3 on
J4 off
J5 on
J6 off
J7 1-2
J8 2-3
J9 2-3
J10 2-3
J11 1-2

Will put it back in the Mega ST now.

[PhilC]

An update RE the 020, I put a different CPU into the Pak and I get as far as the Atari logo and then it either puts bad Rom CRC or tests the memry and it fails.

I sometimes get 2 or 4 bombs or a whole of them

Edit:

Ok, Rom CRC as because of a lose Ram chip, so thats fixed. I got t desktop once but then the Mega reset. So not too worried about the 020 as I'll have a bit of fun working that out.

My 030, the glue isn't sending the 50hz signal, so not reading the rom etc.

[pakman]

Ok, got it.
Your PAK PCB is not the official release, but a later copy with a design flaw. We will fix it..

[pakman]

Furthermore it seems there are no SRAMs assembled underneath the TOS ROMs..

[pakman]

And yes, IDT71B74S20Y or MK48S80 are both fine as well. 25ns is enough for 32MHz.

[PhilC]

Furthermore it seems there are no SRAMs assembled underneath the TOS ROMs..

Do I need the SRam for it to work? And thank you for your help so far. I'll acquire a proper board when I built my next Pak. Where's the best place to get them from?

[Darklord]

Pakman helped me so much when I was working on my Pak 68/3 board.

He's the best. :)

[pakman]

SRAMs are needed for the Second Level Cache, since this is where the cached data is actually stored.
Basically you can run the PAK without SRAMs, but only with the cache disabled.. and thus with lower speed..