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The Memotech MTX Series

Martin Allcorn's Games ROM

Using with REMEMOrizer 

(REMEMOrizer Compatibility added at Board Revision 1.1)

MAGROM Version 1 was not compatible with Andy Key's REMEMOrizer due to the way that REMEMOrizer makes 384K of RAM available in ROM mode, more than a standard MTX was able to provide and more than the current MAGROM design can cope with. This was particularly problematic for users who had removed the original OS ROM to allow REMEMOrizer to provide Andy's enhanced OS ROM as the original ROM would need to be replaced to allow MAGROM to work.

Martin worked out how the MAGROM PCB could be modified to allow MAGROM to coexist with REMEMOrizer and posted the details on the Memotech Forum, they are reproduced on this page. This fix will allow a Version 1 MAGROM to be permanently installed inside the MTX case and available for use with or without REMEMOrizer connected to the external cartridge port. The fix is not required for board revision 1.1 and above.

"Whilst 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
        close to the VIA by pin 8
and then two patch wires fitted :-
        connecting 27A on the left edge connector to Pin 3 of the HCT138
        connecting 26B on both edge connectors to Pin 4 of the HCT138
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 don't HAVE to be yellow, but is does seem to be a Memotech tradition....

What this does is :

  • The P2/P3 mod 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."

Just to prove that red wires work too . . . .     :-)

Some additional photos . . . . these are of MAGROM #31 after Martin did the REMEMOrizer modification for me. The photos should make the terminations of the patch wires a little clearer.


A close-up of the top of the solder side of the board showing the locations of the cut tracks and patch wires.

A close-up showing the three track cuts and patch wires soldered close to the J0 connector.

A close-up showing the single track cut and patch wires soldered close to the J10 connector.



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