The Sinclair QL Forum

Brane2 wrote:I've just stumbled onto copy of QL Service manual online:

http://ciberia.ya.com/rulo_sinclairql/s ... sm_en.html

It does cover microdrives and their ULAs...

Excellent! An online HTML manual which is searchable and has links you can click to go from section to section.

Thanks for reporting that - it may prove very useful.

Dilwyn

I know this is an old thread but has anyone of you got any further investigating the microdrive emulation ? On this forum and on the tlienhard.com forum I started threads about my emulation effort with an mbed http://mbed.org as slave device to the QL emulating a microdrive.

So far I have succeeded in decoding the data coming out of the QL during the format command and am now in the process of emulating the signals back to the QL. Unfortunately although the decoding of the format command signals work, snooping onto the signals during a dir or load command from that working MD tape does not. The timing is somehow different, probably because of motor/tape speed variation. My emulator does not have a PLL function (yet).

For now I am trying to get a directory on screen from an emulated MD tape image file I found with the QLAY emulator (MDV1.MDV).

Maybe I can use the TKII ram disk function to get an image of my only working MD tape I have left (already replaced the pad) and try to get that somehow out of the QL and onto my programming system.

Have you tried contacting Daniele Terdina of Qemulator fame, he must have done something along these sorts of lines, as his emulator also reads MDV image file.
http://www.terdina.net/ql/q-emulator.html

Daniele has a much easier job - he just needed to decode a microdrive image.

I think that what is being sought here, is a means of decoding the signals sent over the actual microdrive port - ie. the electrical signals, which must be interpreted by the microdrive ULA itself to work out what to do with the tape.

I am sure there has been discussion about this elsewhere - the Ian Logan microdrive book is as good a place as any to start, but the problem is that data is just sent in a stream with no timing or anything else to indicate start, middle or end of the signal....

Interpreting the image and understanding it allows you to know what then to look for, especially if the image contains known data. I am assuming some form of logical process here obviously.

I thought that FM always had a base frequency, so that it would be variation around that frequency

Still its good to talk.

As I said, the best bet is Ian Logan's book - ftp://ftp.worldofspectrum.org/pub/sincl ... veBook.zip (21MB) - look at page 28 onwards for details

I think, that Spectrum Microdrive format and QL Microdrive format are too different, and the book will not help.

dex wrote:I think, that Spectrum Microdrive format and QL Microdrive format are too different, and the book will not help.

Indeed, I found much more relevant information in the QL Advanced User Guide.
Pages 302-310 have been very helpful in getting the timing right.

Surely the mechanics of how data is sent to and read from the tape is the same - after all it's the same ULA and you can use a Spectrum microdrive unit with the QL - it's just the way it's stored on the tape which is different....

Didn't realise there was anything in the Advanced QL user guide - - it is online at http://www.worldofspectrum.org/infoseek ... id=2000301 although 94MB !