Acorn Atom and AtoMMC

discussion of games, software, hardware & emulators relating to the Acorn Atom
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RTB
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Acorn Atom and AtoMMC

Post by RTB » Tue Jul 10, 2018 3:57 pm

HI,

I have an Acorn Atom which has the BBC Basic board fitted.

I just wanted to check if anyone knows of any compatibiity problems if I were to add an AtoMMC alongside this board?

Thanks for your help
BBC board.jpeg

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oss003
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Re: Acorn Atom and AtoMMC

Post by oss003 » Tue Jul 10, 2018 6:22 pm

Hello RTB,

in a standard Atom, the AtoMMC board is addressed at the I/O area #B40x and the AtoMMC ROM at #Axxx or #Exxx.
The BBC board shuffles the addresses and the I/O area is moved to #7xxx which does not match with the AtoMMC board.
The MMCROM is an EXTENSION ROM addressed at #Axxx or #Exxx in a normal Atom but at #Dxxx in BBCmode.
So to get the AtoMMC board operational, the ROM should be reassembled to #Dxxx and making use of I/O addresses #740x.

Greetings
Kees
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Last edited by oss003 on Tue Jul 10, 2018 8:07 pm, edited 1 time in total.

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tricky
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Re: Acorn Atom and AtoMMC

Post by tricky » Tue Jul 10, 2018 9:09 pm

Is the 6522 (white socket in the top left I think) required for the AtoMMC board?

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roland
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Re: Acorn Atom and AtoMMC

Post by roland » Tue Jul 10, 2018 9:48 pm

As far as I know the via is not required for an AtoMMC. But I wonder if that bbc card works well without a 6522 :-k

Anyway RTB if you want to use that card, there is an improved version of the original MOS ROM at http://acornatom.nl/atomarch/acl2-12/mosrom. (You might have to skip the first 16 bytes of that file because it's an Atom-in-PC file). I'm quite sure that it needs a 6522 for the TIME statement to work.
256K + 6502 Inside
MAN WOMAN :shock:

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