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Old 11th Nov 2020, 5:57 pm   #109
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 7,096
Default Re: I found it! A very sorry looking MK14.

As Slothie says, although the wiring to the RAMs is scrambled - it was scrambled on the original machines and is scrambled on the issue VI - the wiring to the PROMs is exactly as per databooks so PROM D0 -is- DO, PROM D3 -is- D3, PROM A0 -is- A0, PROM A8 -is- A8, etc. (Bearing in mind that system D4-D7 will actually go to D0-D3 on one of the two PROMs).

I have a device programmer which can read and program most of the PROMs which are pin compatible with the MK14, I have programmed quite a few sets without problems and certainly without having to rearrange the order of bits or addresses in the code. If reading the PROMS you can make your life a little bit easier by making a jig with the high and low PROM wired side by side so you can read the contents of each address from both PROMs as a single 8-bit byte, as that will be easier to compare with the monitor listing (your 'Old' OS PROMs should match the listing in the MK14 V1 manual).

Last edited by SiriusHardware; 11th Nov 2020 at 6:10 pm.
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