The Sinclair QL Forum

Hi, Imre. Thank you for schematic, I still didn't find time for restoring the schematic. C2 - C5 100pF C1 - regular 0.22 uF ( power filters ) R1 - 1.8 KOhm 1% R2, R3 - 330 Ohm 5% R4 - 820 Ohm 5% All diodes - 1N4148 I consider that a problem not only in 2V4 PAL type, but also in the used memory chips...

Thanks, Derek.

I checked JED files.
2V4 and 2V2 is different.

Martin, what problem with the card?
2v2 PAL is only for RAM expansion, you can remove 2v2 PAL and ram chips and check only floppy disk interface.

Thank you Vitaliy! You're English is fine! So, if I've understood correctly, for the TC v2 (6x DRAMs), it seems 'safe' to replace the PAL #1 with a GAL equivalent, but not necessarily safe to replace the PAL #2 with a GAL, due to timing differences, etc between PALs and GALs. I'm guessing that the ...

Hy, Martin. I have JED files for version 2 card ( 6 memory chips ), please see attachment, PAL16L8 and GAL16V8 versions. Only the first GAL ( 1V4 ) work fine, the work of second GAL ( 2V4 ) is not stable, because of RC-delays, which use in schematic, it needs speeds and electrical parameters of PAL1...