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Timbucus · 14th Apr 2019, 1:17 pm

Again keeping more general MK14 stuff in this thread - following SH's suggestion of looking through Practical Electronics I started with the original review (which is reproduced in text on the net) in the May 1979 issue. Off Topic I was shocked when the cover featured the IC insertion tool I had used to help build my replica - surprised I still had it and the elastic was still working! I only lamented it was too small for the 18pin PROMS and RAM!

https://www.americanradiohistory.com...9-05-S-OCR.pdf

I had read the text but, with the photo's I notice that the VDU board he mentions is not the SoC one but, the one built and described in PE itself over three issues from Oct 78 to Dec 78. - just change the number in the url to 11 and 12 to get to the other two parts...

https://www.americanradiohistory.com...cs-1978-10.pdf

This solves the problem of slowing the MK14 and and using its memory with its own onboard 1K. The review also describes the changes needed on Rev I-IV boards to remove the PROM shadow - which is where they map the Video RAM.

I have the parts on the way to build the SoC one but, that looks like an interesting project to reproduce the PCB - not sure if any of the chips are still available...

again as an aside I still have some 7400 chips with the free stickers from the Oct 1978 cover on them...

14th Apr 2019, 1:17 pm	#162
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,364	Re: MK14 schematic revisions Again keeping more general MK14 stuff in this thread - following SH's suggestion of looking through Practical Electronics I started with the original review (which is reproduced in text on the net) in the May 1979 issue. Off Topic I was shocked when the cover featured the IC insertion tool I had used to help build my replica - surprised I still had it and the elastic was still working! I only lamented it was too small for the 18pin PROMS and RAM! https://www.americanradiohistory.com...9-05-S-OCR.pdf I had read the text but, with the photo's I notice that the VDU board he mentions is not the SoC one but, the one built and described in PE itself over three issues from Oct 78 to Dec 78. - just change the number in the url to 11 and 12 to get to the other two parts... https://www.americanradiohistory.com...cs-1978-10.pdf This solves the problem of slowing the MK14 and and using its memory with its own onboard 1K. The review also describes the changes needed on Rev I-IV boards to remove the PROM shadow - which is where they map the Video RAM. I have the parts on the way to build the SoC one but, that looks like an interesting project to reproduce the PCB - not sure if any of the chips are still available... again as an aside I still have some 7400 chips with the free stickers from the Oct 1978 cover on them...