UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - MK14 programming interface

Timbucus · 8th Apr 2019, 8:45 pm

They both look spot on - as you say the second one is a neater solution but, it can then only be used with a JM Precision board - I will have one of Martin's soon so even if I don't make it up as yet, I can check the routing - I am with you that I am sure it will be the same as MK14 v5. Can I suggest you add the pad numbers from 1 at the top down to 16 to clarify it - I did that on my copy.

I had wondered about a simple patch system based on a 14 pin IC socket on the board for the top lines - it would be easy to make up some patches on another two 14 pin sockets for the two we know about already and other machines if they proved to be different - e.g. MK1-5 originals. This will be neater for me than the flying lead I have now as I want to be able to program original MK14's as well... just in case

(or at least Martin's if I make it). I will then just swap my connector soldered to the board for my new one on the flying lead that has all the pins in it... I knew the find was too good to be true of one with Pin 6 missing...

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I also wonder about having an optional two extra TLP that could support the extra rows for using it as a full keyboard interface - again hooked up with the patch system if wanted. I might fancy having a play with that once I add some expanded memory to the MK14 and two extra GPIO on the PI to use... It will be a hack on mine as they will have to go at the bottom but, there is more than enough space on the board for them if started out correctly.

Which leads me to the final conclusion with all 14 connected it would be simpler to have some software switches change over the GPIO Col select in the key14 and send14 programs for board version then.... and save all the above patching... as you did with the SCIOS version...

I will probably add another one in at least for your and KarenO's Cassette / RS232 save trick and hook it to the PI serial port for saving data generated on the machine and to act as a text output terminal...

I was thinking that would add two way comms so the PI could see if the reset had happened as well... try a small save of known data and see if the answer came back!

I also did some testing and I could get KeyPressLength down to 0.024 and KeyReleaseLength to 0.006 - I put ModeChangeSettleTime back to default 0.006 and it was still fine.

I had to set the last time.sleep after reset up to 0.08. I still get the occasional failure but, as I said I get that anyway on the switch - I will investigate a non wallwart switch mode power supply as you suggest - a bigger heatsink, reverse to +Ve outer and one of the hundreds of Spectrum PSU's I have may be better!

On the extra memory topic I found that some samples from the holy grail book are available online in case anyone missed it... The contents at the front and interestingly the whole technical section from the back (Back Matter) are a PDF download which includes a diagram for an extra 1.5K of RAM. If you download the sections they will be named the same so watch out...

https://link.springer.com/book/10.10...-1-349-81357-5

Wow that was a bit of brain dump...

Tim

8th Apr 2019, 8:45 pm	#31
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,363	Re: MK14 programming interface - MK2 They both look spot on - as you say the second one is a neater solution but, it can then only be used with a JM Precision board - I will have one of Martin's soon so even if I don't make it up as yet, I can check the routing - I am with you that I am sure it will be the same as MK14 v5. Can I suggest you add the pad numbers from 1 at the top down to 16 to clarify it - I did that on my copy. I had wondered about a simple patch system based on a 14 pin IC socket on the board for the top lines - it would be easy to make up some patches on another two 14 pin sockets for the two we know about already and other machines if they proved to be different - e.g. MK1-5 originals. This will be neater for me than the flying lead I have now as I want to be able to program original MK14's as well... just in case (or at least Martin's if I make it). I will then just swap my connector soldered to the board for my new one on the flying lead that has all the pins in it... I knew the find was too good to be true of one with Pin 6 missing... I also wonder about having an optional two extra TLP that could support the extra rows for using it as a full keyboard interface - again hooked up with the patch system if wanted. I might fancy having a play with that once I add some expanded memory to the MK14 and two extra GPIO on the PI to use... It will be a hack on mine as they will have to go at the bottom but, there is more than enough space on the board for them if started out correctly. Which leads me to the final conclusion with all 14 connected it would be simpler to have some software switches change over the GPIO Col select in the key14 and send14 programs for board version then.... and save all the above patching... as you did with the SCIOS version... I will probably add another one in at least for your and KarenO's Cassette / RS232 save trick and hook it to the PI serial port for saving data generated on the machine and to act as a text output terminal... I was thinking that would add two way comms so the PI could see if the reset had happened as well... try a small save of known data and see if the answer came back! I also did some testing and I could get KeyPressLength down to 0.024 and KeyReleaseLength to 0.006 - I put ModeChangeSettleTime back to default 0.006 and it was still fine. I had to set the last time.sleep after reset up to 0.08. I still get the occasional failure but, as I said I get that anyway on the switch - I will investigate a non wallwart switch mode power supply as you suggest - a bigger heatsink, reverse to +Ve outer and one of the hundreds of Spectrum PSU's I have may be better! On the extra memory topic I found that some samples from the holy grail book are available online in case anyone missed it... The contents at the front and interestingly the whole technical section from the back (Back Matter) are a PDF download which includes a diagram for an extra 1.5K of RAM. If you download the sections they will be named the same so watch out... https://link.springer.com/book/10.10...-1-349-81357-5 Wow that was a bit of brain dump... Tim Last edited by Timbucus; 8th Apr 2019 at 9:00 pm.