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Here's the start of the include file from Andy's re-constructed source: LSTLOW EQU 0D3FFH BDOSADDR EQU 0D700H LSTHIGH EQU 0D700H JP59K EQU 0D706H CPMLOC EQU 0D708H DSKMSG EQU 0D7BAH DSKERR EQU 0D7C6H ERRFLG EQU 0D7E5H PRINT0 EQU 0D804H CRLF0 EQU 0D80EH CHNL1 EQU 0D840H CHNL2 EQU 0D86AH CHNL3 EQU 0D8...

I think I've worked out why my FDX single came with the 59k "SDX" boot disc: The SDX boot rom loads CPM into RAM at D400, so I guess, if it used the 54k disc that would have to load 5k lower. And that would put the CPM right on the BASIC variables space that usually grows up from C000. The...

I doubt the 54k image was specifically for FDXB, I did some work a while back disassembling that. I'd put my money on it being for extra loadable drivers. Sidisc, Hard drive, HRX even ? FDXB occupies 32k once in ram, 24k is more or less the original 3 roms re-assembled with no paging required.The ex...

Version 2 video board completed, the new one is the one on the left with the square chip and no cassette tape ports. mk2 video board.jpg Lez sent me (via Dave) some extra parts to improve on the original design. The big change is the move to dual ported ram. The square chip is 8k of DP ram. With the...

Version 2.1 of the keyboard interface. Ok there's logic analyser clips all over it, and it's drawing power from the JTAG header on the CFX-II board, but Bill's latest version of the propeller code allows some USB keyboards to work on the MTX. Looking amazingly similar, the PS2 version of the board c...

I have the 2006 Maplin catalogue on the shelf - its still occasionally useful for checking pin outs.

I hardly use Maplin these days, since the drifted away from electronics into gadgets, there's cheaper places for pretty much everything they sell.

The transistor based setup currently on the board also came from Stardot, page 4 of this thread.

http://stardot.org.uk/forums/viewtopic. ... 4&start=90

The Y output is a straight clone of the original Atom's composite out.

It's a 7 bit Atom printer port - as that's what the OS will expect - I have tied the normally floating 8th bit low. Pictures of the colour output as requested, I've a feeling it's the levels on the Y output that are slightly out, or it's the TV not quite accepting the NTSC colour burst. In text mode...

The board containing the rest of the I/O is now ready for testing. Its got a 6522VIA connected to a parallel printer port, and a BBC Micro style User port on a 20 way header. The atom rom contains code to drive the Printer, on channel A. Channel B is unused and free for the programmer and the user p...