Kempston disk interface - Sinclair

This is a discussion on Kempston disk interface - Sinclair ; Hi there people, Firstly apologies if this gets double posted to the group, tried posting via demon but that doesn't seem to be working, so trying giganews.... I seem to be the only person in the known universe that has ...

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Thread: Kempston disk interface

  1. Kempston disk interface

    Hi there people,

    Firstly apologies if this gets double posted to the group, tried posting
    via demon but that doesn't seem to be working, so trying giganews....


    I seem to be the only person in the known universe that has one of these,
    so I have managed to tap out the circuit to it, and am trying to understand
    how everything works, however in typical 80's style, the designers seem to
    have taken several shortcuts, such as incomplete address decoding, and
    diode logic.

    Anyway I'm currently trying to work out how the onboard rom is enabled, as
    I would guess it also sits in the 0-16K reigon, as does the internal ROM.
    However I am unclear as to the function of the /ROMCS line on the spectrum
    expansion connector, looking at the spectrum schematic, it seems to be
    generated by the ULA, but the disk interface also seems to maybe force it
    high also (presumably to disable the internal ROM). Does this make sense ?

    Is there a description somewhere of the meanings of the spectrum bus
    signals, from what I remeber the manuals just list them, obviously the
    majority are just Z80 signals that can be looked up on the Z80 data sheet.

    Having now worked out the circuit for this interface, and entered it into
    Eagle (PCB making program), is there anywhere that I can upload it, so that
    others may have access to it if they ever need it (this asumes that I don't
    have the only one in the known universe....).

    Cheers.

    Phill.

  2. Re: Kempston disk interface

    Prime wrote:
    > Hi there people,
    >
    > Firstly apologies if this gets double posted to the group, tried posting
    > via demon but that doesn't seem to be working, so trying giganews....


    We got both.
    So demon's working.

    > Anyway I'm currently trying to work out how the onboard rom is enabled, as
    > I would guess it also sits in the 0-16K reigon, as does the internal ROM.
    > However I am unclear as to the function of the /ROMCS line on the spectrum
    > expansion connector, looking at the spectrum schematic, it seems to be
    > generated by the ULA, but the disk interface also seems to maybe force it
    > high also (presumably to disable the internal ROM). Does this make sense ?


    That's also how multifaces worked.
    Pressing the red button triggered an NMI which under normal circumstances
    would force the speccy to run a routine in the ROM which causes a crash, but
    it also enabled the overlay ROM in the multiface which had a working service
    routine to handle the NMI.

    > Is there a description somewhere of the meanings of the spectrum bus
    > signals, from what I remeber the manuals just list them, obviously the
    > majority are just Z80 signals that can be looked up on the Z80 data sheet.
    >
    > Having now worked out the circuit for this interface, and entered it into
    > Eagle (PCB making program), is there anywhere that I can upload it, so that
    > others may have access to it if they ever need it (this asumes that I don't
    > have the only one in the known universe....).


    Worldofspectrum is the best repository for all things speccy.
    See if they'll host it on there?
    --
    | |What to do if you find yourself stuck in a crack|
    | spike1@freenet.co.uk |in the ground beneath a giant boulder, which you|
    | |can't move, with no hope of rescue. |
    | Andrew Halliwell BSc |Consider how lucky you are that life has been |
    | in |good to you so far... |
    | Computer Science | -The BOOK, Hitch-hiker's guide to the galaxy.|

  3. Re: Kempston disk interface


    Was this the one made by Abbeydale or whatever it was called? A lot of the
    messing about with various lines was because the Speccy had no ramcs line,
    onlyr romcs which is why things tended to be paged there!

    was also a bug as I recall that had to be fixed in hardware in interfaces.

    Brian
    Brian Gaff....Note, this account does not accept Bcc: email.
    graphics are great, but the blind can't hear them
    Email: briang1@blueyonder.co.uk
    __________________________________________________ __________________________________________________ __________


    ----- Original Message -----
    From: "Prime"
    Newsgroups: comp.sys.sinclair
    Sent: Wednesday, August 13, 2008 12:33 AM
    Subject: Kempston disk interface.


    > Hi there people,
    >
    > I seem to be the only person in the known universe that has one of these,
    > so I have managed to tap out the circuit to it, and am trying to
    > understand
    > how everything works, however in typical 80's style, the designers seem to
    > have taken several shortcuts, such as incomplete address decoding, and
    > diode logic.
    >
    > Anyway I'm currently trying to work out how the onboard rom is enabled, as
    > I would guess it also sits in the 0-16K reigon, as does the internal ROM.
    > However I am unclear as to the function of the /ROMCS line on the spectrum
    > expansion connector, looking at the spectrum schematic, it seems to be
    > generated by the ULA, but the disk interface also seems to maybe force it
    > high also (presumably to disable the internal ROM). Does this make sense ?
    >
    > Is there a description somewhere of the meanings of the spectrum bus
    > signals, from what I remeber the manuals just list them, obviously the
    > majority are just Z80 signals that can be looked up on the Z80 data sheet.
    >
    > Having now worked out the circuit for this interface, and entered it into
    > Eagle (PCB making program), is there anywhere that I can upload it, so
    > that
    > others may have access to it if they ever need it (this asumes that I
    > don't
    > have the only one in the known universe....).
    >
    > Cheers.
    >
    > Phill.





    --
    Brian Gaff....Note, this account does not accept Bcc: email.
    graphics are great, but the blind can't hear them
    Email: briang1@blueyonder.co.uk
    __________________________________________________ __________________________________________________ __________


    "Andrew Halliwell" wrote in message
    news:3mk9n5-hp7.ln1@ponder.sky.com...
    > Prime wrote:
    >> Hi there people,
    >>
    >> Firstly apologies if this gets double posted to the group, tried posting
    >> via demon but that doesn't seem to be working, so trying giganews....

    >
    > We got both.
    > So demon's working.
    >
    >> Anyway I'm currently trying to work out how the onboard rom is enabled,
    >> as
    >> I would guess it also sits in the 0-16K reigon, as does the internal ROM.
    >> However I am unclear as to the function of the /ROMCS line on the
    >> spectrum
    >> expansion connector, looking at the spectrum schematic, it seems to be
    >> generated by the ULA, but the disk interface also seems to maybe force it
    >> high also (presumably to disable the internal ROM). Does this make sense
    >> ?

    >
    > That's also how multifaces worked.
    > Pressing the red button triggered an NMI which under normal circumstances
    > would force the speccy to run a routine in the ROM which causes a crash,
    > but
    > it also enabled the overlay ROM in the multiface which had a working
    > service
    > routine to handle the NMI.
    >
    >> Is there a description somewhere of the meanings of the spectrum bus
    >> signals, from what I remeber the manuals just list them, obviously the
    >> majority are just Z80 signals that can be looked up on the Z80 data
    >> sheet.
    >>
    >> Having now worked out the circuit for this interface, and entered it into
    >> Eagle (PCB making program), is there anywhere that I can upload it, so
    >> that
    >> others may have access to it if they ever need it (this asumes that I
    >> don't
    >> have the only one in the known universe....).

    >
    > Worldofspectrum is the best repository for all things speccy.
    > See if they'll host it on there?
    > --
    > | |What to do if you find yourself stuck in a
    > crack|
    > | spike1@freenet.co.uk |in the ground beneath a giant boulder, which
    > you|
    > | |can't move, with no hope of rescue.
    > |
    > | Andrew Halliwell BSc |Consider how lucky you are that life has been
    > |
    > | in |good to you so far...
    > |
    > | Computer Science | -The BOOK, Hitch-hiker's guide to the
    > galaxy.|




  4. Re: Kempston disk interface

    "Brian Gaff" wrote in
    news:%DQok.42222$E41.24164@text.news.virginmedia.c om:

    >
    > Was this the one made by Abbeydale or whatever it was called? A lot


    Yeah that's the one, I believe it was originally marketed by Watford
    Electronics, who mostly produced stuff for the BBC micro.

    > of the messing about with various lines was because the Speccy had
    > no ramcs line, onlyr romcs which is why things tended to be paged
    > there!



    Indeed, although in this interface there is only ROM & FDC so no ram in
    this case, unlike the multiface.

    > was also a bug as I recall that had to be fixed in hardware in
    > interfaces.


    Well I'm cirtainly having problems getting it to work again....prolly a
    timing problem with all that resistor/diode logic....I may just see if I
    can make a work alike with a CPLD, rom and FDC....

    Cheers.

    Phill.

  5. Re: Kempston disk interface


    Somewhere in my heap of junk here are some discs made on it by OCP when
    writing source code for some of their products. Whether they are still
    readable and exactly where they are in the heap is anyone's guess. I
    certainly had no hardware to read them, They were 5.25 in discs and I looked
    at tem briefly on a pc disc reader running in dos.

    Brian
    Brian Gaff....Note, this account does not accept Bcc: email.
    graphics are great, but the blind can't hear them
    Email: briang1@blueyonder.co.uk
    __________________________________________________ __________________________________________________ __________


    ----- Original Message -----
    From: "Prime" >
    Newsgroups: comp.sys.sinclair
    Sent: Thursday, August 14, 2008 7:09 PM
    Subject: Re: Kempston disk interface


    > "Brian Gaff" >
    > wrote in
    > :
    >
    >>
    >> Was this the one made by Abbeydale or whatever it was called? A lot

    >
    > Yeah that's the one, I believe it was originally marketed by Watford
    > Electronics, who mostly produced stuff for the BBC micro.
    >
    >> of the messing about with various lines was because the Speccy had
    >> no ramcs line, onlyr romcs which is why things tended to be paged
    >> there!

    >
    >
    > Indeed, although in this interface there is only ROM & FDC so no ram in
    > this case, unlike the multiface.
    >
    >> was also a bug as I recall that had to be fixed in hardware in
    >> interfaces.

    >
    > Well I'm cirtainly having problems getting it to work again....prolly a
    > timing problem with all that resistor/diode logic....I may just see if I
    > can make a work alike with a CPLD, rom and FDC....
    >
    > Cheers.
    >
    > Phill.





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