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The Memotech MTX Series |
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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 :- |
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close to pins 3 and 4 of the HCT138 |
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close to the VIA by pin 8 |
| and then two patch wires fitted :- |
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connecting 27A on the left edge
connector to Pin 3 of the HCT138 |
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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.... |
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What this does is :
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The P2/P3 mod changes the range of
memory pages detected by the HCT138 from 0-7 to 0-3
and 8 11.
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The A, B, C inputs to the decoder
having been P0, P1, P2 become P0, P1 and P3.
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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.
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| A close-up of the top of the
solder side of the board showing the
locations of the cut tracks and patch wires. |
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| A close-up showing the three
track cuts and patch wires soldered close to
the J0 connector. |
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| A close-up showing the
single track cut and patch wires soldered
close to the J10 connector. |
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