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

Timbucus · 9th Apr 2019, 12:00 am

Great idea of using it as a general purpose interface - you could even test Spectrum and other more "modern" machine motherboards as well - I think my programmer board may get a refit soon, as I am always scrabbling for a keypad when repairing machines.

That is actually the idea I referred to earlier - I have an Amstrad Grey keyboard on a dead 128 which would make a nice keyboard for the MK14 as it is a 4x10 matrix! Just need a TESLA prom programmer now for some custom SCIOS - ah well on the project queue with the half built Alpha Micro...

On the timing I have not been able to reduce below 0.024 for key press length a factor of 7 more than your 0.0035 so something is different (and not the PI0 and PI0W as you use time.sleep which is a hardware timer) - maybe my IC11 74LS365N substitute for the DM80L95N - we would need to compare data sheets but, it is certainly possible it needs longer to latch a valid value, that might really need adjustment of R7-R10 pull ups that has not been accounted for in that substitution?

9th Apr 2019, 12:00 am	#33
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,364	Re: MK14 programming interface - MK2 Great idea of using it as a general purpose interface - you could even test Spectrum and other more "modern" machine motherboards as well - I think my programmer board may get a refit soon, as I am always scrabbling for a keypad when repairing machines. That is actually the idea I referred to earlier - I have an Amstrad Grey keyboard on a dead 128 which would make a nice keyboard for the MK14 as it is a 4x10 matrix! Just need a TESLA prom programmer now for some custom SCIOS - ah well on the project queue with the half built Alpha Micro... On the timing I have not been able to reduce below 0.024 for key press length a factor of 7 more than your 0.0035 so something is different (and not the PI0 and PI0W as you use time.sleep which is a hardware timer) - maybe my IC11 74LS365N substitute for the DM80L95N - we would need to compare data sheets but, it is certainly possible it needs longer to latch a valid value, that might really need adjustment of R7-R10 pull ups that has not been accounted for in that substitution?