REMEMOrizor compatibility

Everything about Martin Allcorn's Games ROM
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Martin A
Posts: 414
Joined: 09 Nov 2013 21:03

REMEMOrizor compatibility

Post by Martin A » 30 Apr 2014 15:01

In one of the other discussions here, I mentioned that Magrom won't work with REMEMOrizor.

Whist the software is compatible, there is a hardware issue, as the REMEMOrizor provides more memory pages than the Magrom is designed to work with.

This is the fix, at the expense of RS128 compatibility.

Signals P2 and P3 from the memory paging port need to be swapped over, at the HCT138, this requires 3 tracks to be cut;
close to pins 3 and 4 of the HCT138 and,
close to the VIA by pin 8.
and then 2 patch wires:
Connecting 27A on the left edge connector to Pin 3, and
26B on both edge connectors to pin 4

The track to the top pin on the selector also needs cutting and a wire fitted connecting pin 7 to the top selector pin.

NB the patch wires dont HAVE to be yellow, but is does seem to be a Memotech tradition...

What this does is:

The P2/P3 changes the range of memory pages detected by the HCT138 from 0-7 to 0-3 and 8 11.The A B,C inputs to the decoder having been P0,P1,P2 become P0,P1 and P3. Output Y7 of the HCT138, now represents memory page 11. Which is the memory page that the magrom will use in place of page 3 which would have been the case with RS128 selected.

As the MTX500 and MTX512 settings haven't been altered, Magrom will continue to work with 32 and 64k systems, provided the jumper is moved.
Attachments
Magrom Changes.jpg
Patched Magrom
Magrom Changes.jpg (204.05 KiB) Viewed 1406 times
Last edited by Martin A on 01 May 2014 22:21, edited 1 time in total.

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Dave
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Joined: 11 Aug 2012 18:16
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Re: REMEMOrizor compatibility

Post by Dave » 30 Apr 2014 15:55

Thanks Martin,

a useful "fix" / enhancement.

regards
Dave

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