ICL OPD

[stephen_usher]

No-one has usable OPD schematics let alone CAD files.

[Chr$]

Ah yes, sorry I should have actually looked at the files with KiCad and not just Gerber viewer.

Blimey though, those WD1772 chips are expensive to source. I thought I'd have one somewhere, but it was the WD1770 I was confusing it for.

[stephen_usher]

Exxos has some in stock.

The PCB itself isn't documented really as it was only for my consumption as a prototype board, hence lack of info it the Gerber files.

[Pr0f]

There were some second source makers for these chips - such as VLSI - VL1772 - and I think there was a couple of versions that were practically interchangeable too 1771 if memory serves.

[stephen_usher]

It looks like the disk image I was using to test was corrupted.

This may have been due to the Gotek's FlashFloppy version being old or because I had pin 34 set to change rather than ready. It certainly writes more quickly now.

Anyway, the converted version now mounts in DOSBox but something is not right as "type test.doc" seems to show the contents of the profile file instead.

Anyway, here are the images along with an HFE format file which contains the same data.

P.S. Using the converted floppy image on the OPD still works, suggesting that the firmware ignores the boot block.

[stephen_usher]

JobDone has managed to fix the C1 floppy interface's ROM so that it now formats a drive that MSDOS and the Atari ST can read and write to. Windows 10 barfs on it, however.

I'll be doing some more verification before we publish it.

Technical bit:
The ROM blindly writes a string held in the ROM to the start of the boot sector of a drive during the format. Replacing the contents of this string with the correct PC boot parameter block information allows other machines to determine the way it's been formatted and use it normally.

[stephen_usher]

Here's a file written on another machine and imported into Quill without difficulty.

[stephen_usher]

Well, the floppy formatted on the C1 interface with the modified ROM passes every interoperability test so I think it's safe to publish.

Note that to use it with the OPD a floppy has to be first formatted on the OPD as the format isn't the default used by MSDOS or the ST.

[jobdone]

Hopefully see that OPD in action at some point.

[Chr$]

My PCB's should arrive soon. I have all the other components together and will temp pinch the WD1772 from my Trump card for now.

Obviously the ICL Basic is different in many respects to normal QL basic, I wonder if it would be possible to run QL basic somehow on an OPD? Or would it be too restricted by the limited 128k RAM and not to mention other hardware differences? It would really make an OPD some much more useful if it could do at least some QL stuff. ICL Basic on a ROM somehow would be a start I suppose and I read somewhere here that that's being looked into.

And is it possible Stephen, if in your improved/upgraded interface that it could use the more common WD1770 instead of WD1772?