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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 12th May 2019, 11:47 pm   #81
SiriusHardware
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Default Re: MK14 programming interface - MK2

I didn't realise the diagram for MK14man's version was available anywhere - I confess I have not been to his site for a while because he seemed to have gone completely off-grid for a number of years - but maybe the details were always there and I just missed them. I don't seem to be able to compete with your (by now legendary) data mining ability.

Although it's good that the programmer could work with the MK14man design after all, that design is so flexible in terms of how the address decoding is done that it ought to be quite possible to reserve an address range as PROM, map some of the non-volatile memory into that range and provide the machine with built-in serial download routines, if indeed that is not already the case. Or, the existing cassette handling routines and jump calculator could of course be replaced with serial download code.

For original machines I considered it essential that the method used should not require any modification at all to the hardware / firmware or consume any RAM or hardware resources not already used by the monitor, so that was why I ended up doing it the way I did.

It was an accidental bonus that it turned out to be possible to upload code at much higher speed than I had expected - I had thought the OS's key debounce delay would limit the upload speed far more than it does.
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Old 25th Jun 2019, 6:35 pm   #82
SiriusHardware
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Default Re: MK14 programming interface - MK2

Another little dribble of information, another forum member has confirmed that the external keypad connector on his original issue V MK14 has the same connection layout as the external keypad connector on my original issue II, around which this programmer project was made.

This implies that original issue III and issue IV MK14s probably have the same external keypad connector layout as well, although nothing is certain when it comes to Science Of Cambridge.

There remains the question of whether the 'Issue V' Czech replicas made by Martin L also have the original MK14 keypad edge connector layout. If anyone knows for sure, please let us know.
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Old 25th Jun 2019, 7:59 pm   #83
Timbucus
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Default Re: MK14 programming interface - MK2

Good to know - we are slowly closing the knowledge gap!

Quote:
Originally Posted by SiriusHardware View Post
There remains the question of whether the 'Issue V' Czech replicas made by Martin L also have the original MK14 keypad edge connector layout. If anyone knows for sure, please let us know.
I am 99% certain it is - I have not built the board as yet but, tracing the tracks they seem to go to the same pins I can see in photos online on IC13 on real ones - which seems to support the same layout. The routing on the JM Precision is very different as a lot are taken from the switches rather than direct tracks.
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Old 15th Jul 2019, 9:37 pm   #84
SiriusHardware
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Default Re: MK14 programming interface - MK2

Another different, brilliant (and potentially very fast) way of getting code into an MK14, three videos (in chronological order) on the subject from the creator of the JMP replica MK14s.

https://www.youtube.com/watch?v=yg2P5I3URrw

https://www.youtube.com/watch?v=-_N0OOj-uvs

https://www.youtube.com/watch?v=0OytcbqWwAY
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Old 15th Jul 2019, 10:12 pm   #85
Timbucus
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Default Re: MK14 programming interface - MK2

Had an OP80 on my watch list for sometime - that seals the purchase decision I think... nice spot on the videos.
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Old 15th Jul 2019, 10:41 pm   #86
SiriusHardware
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Default Re: MK14 programming interface - MK2

One I missed earlier (The fourth in the series).

https://www.youtube.com/watch?v=y6xaCgKht-I
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