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Thread: Mark 8 variant

  1. #11

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    Hello Corey,

    Thanks for the link! I have to figure some stuff out. The machine has 14K of memory.
    So that should give some possibilities

    And I've got also these books (and more). Games for the 8008.

    Mark 8 17.jpg

    The constructor of the computer really enjoyed the
    pictures of the machine working again for so far.

    He told me they ran moon lander on the machine once.
    There is a complete book of scalbi basic with the machine.
    There are some notes in it because of different I/O addresses.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  2. Default

    Most SCELBI software that I have seen doesn't include I/O drivers. For example the Galaxy program is listed as 4K, but doesn't include any I/O software at all. I had to work pretty hard on tweaking it in order to make it fit in 4K with the added and necessary I/O drivers. A lot of the early/mid 70's home computer gear left a whole a lot to the user to figure out. This is very different than what we are used to with todays canned solutions for everything.

    If you come up with any additional 8008 software, I'd be more than glad to host it on my 8008 software page.

    regards,
    Mike W.

  3. #13

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    Hello Mike,

    When I have time I will try to sort things out. There are many documents
    that came with the machine. Probably a nice winter project.

    An other thing is that my scanner is not supported under windows 8.1... That's also for
    the winter. Maybe I will buy a new and faster one... Than I can scan the documents.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  4. #14

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    Can anyone tell me where I can find little test programs to test a Mark 8?
    I've wiped the dust off of my Mark8. The last time I had the machine ready
    to select a memory address and put data into that address.

    Mark 8 display 123.JPG

    So now it is time to do a little more testing... I found many big programs
    and futuristic stuff. But I would like to have a list of basic test programs.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  5. #15
    Join Date
    Jun 2012
    Location
    UK - Worcester
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    3,853

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    Hi Roland,

    Did you ever manage to dump the EPROM in the end?

    I have been interested in the 8008 for a while. Too much of a faff to make a real one (although people keep tempting me) so I constructed a JavaScript emulator capable of looking like a Scelbi, Mark-8 or MIL MOD-8.

    I note that you have a few interesting additions to your machine (LED 7-segment displays for instance). Are these described anywhere or were they 'homebrew' by the original constructor do you know?

    I have just bought myself a little ESP8266 to run the i8008 emulator as a little project whilst in lock-down (although I am working from home and have less free time now than I did before lock-down!).

    I would be interested in writing a few simple test programs for you if you can pass me details of your I/O capability on the machine.

    I would also be interested in converting the HexPawn program from the games manual to run on your machine if you would be interested...

    By the looks of the back panel there is/was a serial port at one time of day. Just thinking of how to get the user to interact with the machine...

    Any means of saving to tape once you have loaded something by hand?

    A bit of a distraction me thinks...

    Dave

  6. #16

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    Hi Dave,

    The EPROM is a project which I have to start over... It is too long ago
    I had some contact with Martin Eberhart about reading the chip.
    He told me that he has seen some chip failures where the internal
    voltage reference is drifting away from 0. (The chip has no GND pin)
    So I have to play with the eprom with different voltages. We will see.

    But I think it has a bootstrap for the cassette reader. So if the chip is really broken
    then it is probably not rocket science to use/edit an existing loader... (I hope)

    There is a lot of documentation with this machine. I have to make that digital.
    I now have an A3 scanner, so that should be a bit easier to do now.
    But I'm pretty sure that I don't have all the documentation... There is a lot which I
    have to draw back from the circuit boards...

    The machine has also a board with a MCM6571 character generator.
    So it has its own display card as well! There is a composite output on it.
    I wonder what kind of OS they ran on it. Especially because
    this machine has quite a lot of RAM. (14KB)

    There is also a 12 pin keyboard connector on it. But I didn't get the
    keyboard unfortunately. So any suggestions on that one would be nice!

    But I'm sure that they used standard circuits from magazines etc.

    The 7 segment LED displays were done in a very simple way.
    Just use a BCD to 7 segment on de LED outputs and you are done

    The man told me that he and his brother build two Mark 8 machines.
    But they got really annoyed by the LEDs and switches.
    That is why they made the programming interface.
    The programming device is done by a shift register. I have drawn
    the schematic from the PCB because there was an error on it.
    This is also something I have to make a copy from...

    I have to say, that interface works really great!

    But if you could help me with a few test programs to check memory etc,
    then that would be great. I don't have any experience with 8008 code.
    I will check what I have for documentation. I hope this will help to find
    the background on the cassette, monitor, keyboard and memory expansion.

    Here are some more pictures: http://technischmuseum.nl/devices/Ma.../Mark%208.html

    Regards, Roland
    Last edited by Roland Huisman; May 6th, 2020 at 12:40 PM.
    WTB: Case for Altair 8800 ...... Rolands Github projects

  7. #17
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,853

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    Glad to help out Roland - it will be an interesting diversion to do something different...

    Thanks for the website pointer to the excellent photographs. I will try and decipher the Dutch with my knowledge of German. It looks fairly straight forwards... If I get stuck, my son is learning Dutch whilst he is in lockdown!

    Dave

  8. #18
    Join Date
    Jul 2014
    Location
    New Hampshire, USA
    Posts
    194

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    As follow up to earlier questions, the 4702A and 8702A were the MCS-4 and MCS-8 equivalent numbers for the 1702A. Electrically they are identical.

    Martin Eberhard's ME 1702A programmer is excellent and works very nicely.

    Another alternative which is sleek (but much tougher to construct) is Matthew Millman's 1702A Arduino Shield. Construction is not for the faint-of-heart but it's amazing to have a 1702A programmer that is not much larger than an Altoid tin! http://tech.mattmillman.com/projects...-1702a-eproms/

    - Gary

  9. #19
    Join Date
    Oct 2017
    Location
    Kentucky USA
    Posts
    115

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    Quote Originally Posted by Roland Huisman View Post
    Can anyone tell me where I can find little test programs to test a Mark 8?
    I've wiped the dust off of my Mark8. The last time I had the machine ready
    to select a memory address and put data into that address.

    Mark 8 display 123.JPG

    So now it is time to do a little more testing... I found many big programs
    and futuristic stuff. But I would like to have a list of basic test programs.

    Regards, Roland
    I'd say, that is the nicest functioning front panel for an 8008 I've ever seen, although the MIKE series 8008's from Martin Research (see Byte magazine #1, first ad page) come close. BTW I worked in the 80's for the successor to Martin Research, Qwint Systems, run by the Martin Research founders.

  10. #20
    Join Date
    Oct 2017
    Location
    Kentucky USA
    Posts
    115

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    Quote Originally Posted by gekaufman View Post

    Another alternative which is sleek (but much tougher to construct) is Matthew Millman's 1702A Arduino Shield. Construction is not for the faint-of-heart but it's amazing to have a 1702A programmer that is not much larger than an Altoid tin! http://tech.mattmillman.com/projects...-1702a-eproms/

    - Gary
    That 1702A programmer is a freaking work of art; I'd daresay that is the finest 1702A programmer ever made or ever will be made. And I was so proud of my 2704/2708 PIC-based programmer that also used (off the shelf) step-ups from a USB power supply...

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