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Old 14th Apr 2018, 10:44 am   #4
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: MK14 schematic revisions

...I'm away from base just at the moment, but just before I came away I had a hunt through my archive of MK14 related stuff and found a single sheet document, sent at my request from S.O.C. describing fairly extensive modifications for early issue MK14s like mine, the purpose of which were to remove the unwanted PROM images from the address range 0200H to 07FFH.

If these mods were done, it was then possible for the user to map 1.5K of added-on offboard memory into the address block no longer occupied by the PROM.

On reflection, this is probably one of the rarest original MK14 documents around, so I'll scan it and post it here - my scanner is so old that it only works with Win XP, so I'll have to drag out another semi antique in order to do that.

My thought is that the late(est) issue of MK14 PCB may actually have incorporated these mods. The simplest way to find out is for someone with an issue V machine to have a look through 0200H-07FFH and see if there are PROM images present there.
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