New QL user & owner

[XorA]

With the upper 16K missing the RAM test should still work as this lies within the first 16K ROM. Given the fact that the test pattern doesn't appear, it looks like there is another hardware failure.

Without knowing what is on the roms, we do not even know there is a RAM test though!

[XorA]

I think personally my next step would be to check the content of those ROM chips and of course try a known working pair (or single 27512 type), written with a ROM of the full 48kb. Those 27128 chips are both only 16kb (as mentioned before) so it's possible it had an external ROM dongle originally, which is now missing.

Might not be that easy though, as one is labelled 0000 and the other 4000 (and the code from 8000 onwards 'was' external. Normally they are 0000 and 8000 internally. So I think would indicate that addressing might be different. Someone else will be able to offer a better insight.

I agree with Chr$ if you have an eprom programmer than dump the roms, we can then examine them in dissasembler/emulation to see what they actually do!

[RWAP]

I can supply a set of JM ROMs for testing, plus the missing LED wires and whatever screws are missing to help get this back to factory condition (assuming the LEDs were ever fitted) - just need the cost of postage as it is such a good find, it would be useful to get it up and running and see what happens.

[QLvsJAGUAR]

I can supply a set of JM ROMs for testing, plus the missing LED wires and whatever screws are missing to help get this back to factory condition (assuming the LEDs were ever fitted) - just need the cost of postage as it is such a good find, it would be useful to get it up and running and see what happens.

Thanks Rich for offering support with mass production materials.

But as Chr$, myself and others mentioned, this QL should be left/restored as it originally was. No ROMs, just EPROMs. No LEDs as they were not ready when this machine was build.

[QLvsJAGUAR]

Hello Urs. I kept meaning to tell you that your images at:

https://www.sinclairql.net/pic/

don't work, but I suspect you've noticed that (hence the onedrive images)!

Thank you Chr$ for letting me know.

Recently it was cold and rainy and I had/made some free time to get several things fixed on the sinclairql.net website , the QL Picture Gallery is now (again) OneDrive only.

[QLvsJAGUAR]

- Most likely this QL came with a ROM port dongle holding at least additional 16 KB of the firmware (in a third 27128 EPROM IC), usually labelled 8000 (at address 8000 Hex). Do you have got a ROM port dongle or any additional EPROM ICs?

I did some investigation, tracking back the seller of this QL on ebay. There was a second auction from the same seller where the
"Sinclair QL EPROM Cartridge Board with an EPROM labelled 13-2-84 8000 0D0C as checksum" was sold. Most likely this would fit to this QL computer with the ZX-83 PCBA. See picture.

Key question is who the buyer of this is!?

[janbredenbeek]

I did some investigation, tracking back the seller of this QL on ebay. There was a second auction from the same seller where the
"Sinclair QL EPROM Cartridge Board with an EPROM labelled 13-2-84 8000 0D0C as checksum" was sold. Most likely this would fit to this QL computer with the ZX-83 PCBA. See picture.

That 'checksum' needs some investigation... Key question is how it's generated. I've tried byte-sum, word-sum (both big- and little-endian) and word-XOR on FB, PM, AH, and JM ROMs (8000-BFFF) but none of the results looked like 0D0C.
- edit: the '0D0C' should probably be read as 'QDOS', since the other two ROM's stickers had 'BASIC' on it!

[QLvsJAGUAR]

0D0C as checksum

That 'checksum' needs some investigation... Key question is how it's generated. I've tried byte-sum, word-sum (both big- and little-endian) and word-XOR on FB, PM, AH, and JM ROMs (8000-BFFF) but none of the results looked like 0D0C.
- edit: the '0D0C' should probably be read as 'QDOS', since the other two ROM's stickers had 'BASIC' on it!

That‘s a very good read and conclusion, Jan.


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