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Microdrive

HZJHZJ
edited August 2014 in Hardware
Hi,
I'm trying to emulate the microdrive, and to analyse the data structure on the cartridges. But my measurement of the timing of the signals differs from those described by Ian Logan in "The microdrive universe". In particularly, the band gaps are of length 2.3ms/3.0ms and not of 3.7ms/7.0ms, and not the bits on the both tracks are shifted against each other by one half, but the bytes!

If somebody in this forum has experience in this field, I would be grateful for some help!:-)

HZJ
Post edited by HZJ on

Comments

  • rwaprwap
    edited August 2014
    Are you aware of the microdrive emulator and work done by gertk - see the QL forum:

    http://qlforum.co.uk/viewtopic.php?f=2&t=584

    There has been no news on this for some time, but his work may help (I know someone else was looking at the Spectrum version) but can't spot the link to where this was being discussed...
    Supporting Sinclairs since 1986 !

    www.rwapsoftware.co.uk
    www.sellmyretro.com
  • Paddy ColemanPaddy Coleman
    edited August 2014
    rwap wrote: »
    Are you aware of the microdrive emulator and work done by gertk - see the QL forum:

    http://qlforum.co.uk/viewtopic.php?f=2&t=584

    There has been no news on this for some time, but his work may help (I know someone else was looking at the Spectrum version) but can't spot the link to where this was being discussed...

    What a great project - I see you have posted a request for an update on the QL forum Rich. I have to say the ZX Spectrum with Microdrive was a great fun and I really loved mine back in the 1980s. It is a shame that Sinclair put a 128K limit on the QL MDs though. Was the limit the same on the ICL OPD MDs or did the work they did on the MD design go beyond this?

    Paddy
  • HZJHZJ
    edited August 2014
    rwap wrote: »
    Are you aware of the microdrive emulator and work done by gertk - see the QL forum:

    http://qlforum.co.uk/viewtopic.php?f=2&t=584

    There has been no news on this for some time, but his work may help (I know someone else was looking at the Spectrum version) but can't spot the link to where this was being discussed...
    Yes, I know this project, it was also presented in the German forum some month ago. I had also a conversation with Gert about it and I learned a lot from him. My idea was to transfer the project to the Speecy, but there seem to be some essential differences concerning timing and coding of the data.
    Regards, HZJ
  • rwaprwap
    edited August 2014
    Ah I knew from Gert that someone had been looking at the Spectrum side of the emulator - I did not realise it was you. :)

    The 128K limit affects all microdrive cartridges unfortunately, including those on the ICL OPD / Merlin Tonto.

    Part of the work behind the microdrive emulator project linked above, including creating a new driver which would allow the QL (and presumably the Spectrum) to overcome that limit when accessing virtual microdrives on the emulator.
    Supporting Sinclairs since 1986 !

    www.rwapsoftware.co.uk
    www.sellmyretro.com
  • HZJHZJ
    edited August 2014
    rwap wrote: »
    Ah I knew from Gert that someone had been looking at the Spectrum side of the emulator - I did not realise it was you. :)
    It was me, but I stopped working on this project for a couple of month. Now I got interested again, and it would be nice to find somebody else who want to join the project, since shared fun is doubled fun.
    Concerning the 128k limit: I won't overcome this - I just change the SD-card for the next one.
    P.S. By the way, it is easy to simulated 8 drives simultaneously, so we end up with 8x128k=1MB
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