Atari 1090 XL Expansion Cards

EXPANSION CARD #1:

Atari 1090 CP/M Module.   This expansion card would have allowed an Atari computer to run software written for Zilog Z-80 processor CP/M (Command Processor/Module) computers.   The card contains a Zilog Z-80 processor and support circuitry.   However this board has not been able to be tested since no software drivers have yet been found.   The card does contain an expansion header, it is unknown whether or not this header may have been used for a daughter card with RAM or perhaps a floppy disk controller board or some other feature.

EXPANSION CARD #2:

Atari 80 Column Video Module.   This is a bare unfinished board.   It capabilities are unknown.  Whether or not it had character attributes and multiple split screens similar to the Atari Corp XEP80 80 column/parallel port module is unknown.   However it is most likely a necessary board in conjunction with the CP/M module since most CP/M software would have functioned more properly in an 80 column mode.

EXPANSION CARD #3:

Atari 64K Memory Module.  Up to 3 of these modules could have resided within the 1090XL expansion chasis.  They would be diasy chained together via the expansion header located in the top center of the card.  The card had 2 "Personality" modes.  One mode was the "Bank Switching" mode for use with the 800XL, 1400XL and 1450XLD.  The second mode was the "1064" mode which would have allowed a single memory card to act as a 1064 expansion module.  (The 1064 Epansion module was a 64K box which could only plug into an Atari 600XL giving it 80K of total memory).