Upgrade to QFLP does not work

[Dave]

What is it about the default image that works that you do not like?

If it's the fdk_ instead of flp_ can you search and replace the pattern "fdk" with "flp" in the ROM image?

[1024MAK]

Pin 26 on the ROM socket is likely not connected (this pin is not used on 2764A 8k byte EPROMs) to anything. It maybe acting like a little antenna, picking up spikes and causing the 27128 EPROM to change address (it is address pin A13), during the change, invalid data may appear on it's data output pins before correct data reappears.

So remove the EPROM, carefully check the board, top and bottom. Test using a meter on resistance between +5V and pin 26. Do the same between 0V/ground and pin 26. If it does appear to be unused, solder a resistor between pin 26 and 0V/ground (e.g. pin 14). The value is not critical, 470 ohm to 2.2k should do the trick. If you are very confident that there is absolutely no existing connection to pin 26, you can instead just connect a wire in place of the resistor.

Mark

[schombi]

Thank you Mark, sounds like a good plan. I also ordered myself a NOS 2764 EPROM. I will try it out and report back.

@Dave: Yes, I mainly got annoyed by the FDK1_, but also that disks cannot easily be renamed and I thought replacing the EPROM would be dead easy, as it often is in the Spectrum add-on world.

[schombi]

Wow, at least for one of my "problem children" I could finally find a solution.

I ordered a NOS EPROM ST 2764A from Ebay, programmed "QFLP for Micro P Disc V.124" on it, replaced the original EPROM on the Micro P controller and - hooray - the ROM message appears on the screen and FLP1_ is accessible

Thanks everybody for your inputs!

[schombi]

Finally the photographic proof