Image Map Image Map
Page 1 of 9 12345 ... LastLast
Results 1 to 10 of 83

Thread: Science of Cambridge (Sinclair) MK14

  1. Default Science of Cambridge (Sinclair) MK14

    Hi all,

    Bit of a longshot this as I know this is a very rare computer but:

    Does anybody out there know how the keyboard on a Science of Cambridge MK14 is constructed? I purchased one recently and the keyboard seems to be missing the contacts that go into the "Circle Domes" mentioned in the training manual. Which means pressing a key doesn't do anything.


    Thanks!

  2. #2
    Join Date
    Jun 2011
    Location
    Portsmouth, England
    Posts
    258

    Default

    Quote Originally Posted by dansretropod View Post
    Hi all,

    Bit of a longshot this as I know this is a very rare computer but:

    Does anybody out there know how the keyboard on a Science of Cambridge MK14 is constructed? I purchased one recently and the keyboard seems to be missing the contacts that go into the "Circle Domes" mentioned in the training manual. Which means pressing a key doesn't do anything.


    Thanks!
    I had an issue 2 kit, the keyboard consisted of a "conductive" rubber pad topped by a piece of flat plastic printed with the key functions, with issue 4 boards came a set of plastic buttons, then there was a metal plate to hold everything down, this was all held in place by 4 plastic pegs passing through the assembly into the PCB.

    Of course many people simply connected a better keyboard using the side connector.

    P.S If you have the manual there is a drawing inside that shows all this, but as you are asking, I will assume you do not have the manual.

    There is a manual on-line and I will update this post with a link when I find it.

    Here is a pdf http://s400081762.websitehome.co.uk/manuals/main.htm
    Last edited by mnbvcxz; November 21st, 2012 at 11:56 AM.

  3. #3
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,716

    Default

    Beware on the circuit diagram (however) that the four key lines going into IC11 do not emerge on data lines D4..D7 as implied.

    Keys 0-7 appear on D7; keys 8 and 9 appear on D6; keys GO, MEM, ABORT and TERM appear on D5 with the remaining keys (A, B, C, D, E and F) appearing on D4.

    If you are repairing the existing horrid keyboard then this shouldn't matter. If you are thinking of adding an external keyboard then it may.

    Page 7 of the MK14 manual is what you are looking for.

    Did you buy the MK14 off e-bay? I noticed a guy had one for sale the other day and it disappeared from the auction before the end was due.

    I had an MK14 many years ago and am in the process of building a home-made breadboard version to recreate the 'experience'. Well done on acquiring one though.

    I have also just completed an FPGA version (complete with the VDU interface and everything) that I will be putting on opencores.org presently once I can shake the bugs out of it.

    I am also in the UK (Worcester) so if there is any information you want regarding the MK14 (and I can be of help) just PM me.

    Dave

  4. #4
    Join Date
    Jun 2011
    Location
    Portsmouth, England
    Posts
    258

    Default

    I used to have an assembler for the MK14 but lost it over the years, it was just 2 sheets of paper with the machine code listing and instructions on how to use the assembler, do you happen to have a copy or know if it is on-line somewhere?

  5. #5
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,716

    Default

    I don't remember an assembler that ran natively on the MK14 (that would be cool if a copy could be found though...)

    I use the TASM cross-assembler hosted on a PC for my development (see http://www.robsons.org.uk/archive/me...4emu/howto.htm).

    Dave

  6. Default

    Thanks for the info guys and the links, they've been very useful.

    I had an issue 2 kit, the keyboard consisted of a "conductive" rubber pad topped by a piece of flat plastic printed with the key functions
    The MK14 I have is also an issue 2, so I'm just missing the "conductive" rubber pads you mention for each key. Any suggestions for suitable replacements? I guess I could make them myself.

    Did you buy the MK14 off e-bay? I noticed a guy had one for sale the other day and it disappeared from the auction before the end was due.
    I did indeed, last week. It was listed as a buy-it-now and I arranged to go and see it on the Saturday and purchased it then, quite lucky really to find one of these with a buy-it-now that hadn't already been sold.

    It seems to work, just the display shows incomplete digits but I think if I swap some of the IC's related to the display on there it might fix it.

    Thanks for your help!

    Dan

  7. #7
    Join Date
    Jun 2011
    Location
    Portsmouth, England
    Posts
    258

    Default

    Quote Originally Posted by dansretropod View Post
    Thanks for the info guys and the links, they've been very useful.



    The MK14 I have is also an issue 2, so I'm just missing the "conductive" rubber pads you mention for each key. Any suggestions for suitable replacements? I guess I could make them myself.


    I did indeed, last week. It was listed as a buy-it-now and I arranged to go and see it on the Saturday and purchased it then, quite lucky really to find one of these with a buy-it-now that hadn't already been sold.

    It seems to work, just the display shows incomplete digits but I think if I swap some of the IC's related to the display on there it might fix it.

    Thanks for your help!

    Dan
    It was a single peice of rubber the same size as the whole keyboard, you really would be better off with an external keyboard.

    A couple of years ago an mk14 was listed on ebay. but if you read the description (which I did), it turned out that the rubber pad was the only part of the mk14 that was on offer!
    The listing was removed.

  8. #8
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,716

    Default

    Dan,

    You might find this website useful "http://www.zoflex.com/". I am sure there is a comparable UK company if you can find them.

    If it is complete digits that are missing then this could be down to either IC12, IC13 or the display itself (or the flexible cable linking the calculator display to the PCB - which has been known to fracture). If it is IC12 or IC13 then some of the keys will probably not work either (as these ICs are not only used to drive the display but also scan the keyboard).

    If individual segments are missing - this could be down to IC9, IC10, IC14 or IC15. IC9 and IC14 handle segments 'a', 'b', 'c' and 'd' whilst IC10 and IC15 handle segments 'e', 'f', 'g' and 'dp'. (Or the cable again)...

    Dave

  9. Default

    If it is complete digits that are missing then this could be down to either IC12, IC13 or the display itself (or the flexible cable linking the calculator display to the PCB - which has been known to fracture). If it is IC12 or IC13 then some of the keys will probably not work either (as these ICs are not only used to drive the display but also scan the keyboard).

    If individual segments are missing - this could be down to IC9, IC10, IC14 or IC15. IC9 and IC14 handle segments 'a', 'b', 'c' and 'd' whilst IC10 and IC15 handle segments 'e', 'f', 'g' and 'dp'. (Or the cable again)...
    Thanks for the info. Dave, very helpful, I've got some on order, will give them a try when they arrive.


    Thanks,

    Dan

  10. #10
    Join Date
    Jun 2011
    Location
    Portsmouth, England
    Posts
    258

    Default

    Here is a picture of an MK14 where individual switches have been mounted on the PCB in place of the original keyboard.

    http://www.old-computers.com/history...l.asp?n=37&t=3

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •