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There’s only one way to go and that’s forward ….

Not much happened with the project over the Christmas holidays .. we had a sad event in our house … my Mother-inlaw passed away on Christmas Day … she wasn’t your stereo-typical Mother InLaw thats for sure. We are going to miss her greatly but now she is with those who have gone before  …

Plans now are to split the efforts on two fronts …

 a) wire up the original SRAM portion of the IIcmxp prototype. This is all 5-volt stuff – just to prove that it works – I am pretty confident it will. I plan to possibly detach the AVR/CPLD/CF portion and glue that onto the development board pictured before.

b) carrry on with the development board and decide/work out how I will do the SDCard interface. ie with or without a CPU helper. I have been reviewing Alex Freed’s AVR, Verilog and 6502 code from the  Pseudo Disk  project to see how it ticks and to determine if I can re-use any of it for this project ( the ProDOS block driver portion that is not the 140K disk image part) . The alternative is to add a SPI Master port in the CPLD and interface that directly to the 6502  .. the kicker here is that there are only 4 i/o addresses available in the memory interface  A0 & A1 (to keep it compatible with the original memoruy expandable IIc. The IIc+ added A2 and A3)

I want the i/o interface to be as transparent as possible so that the RAM interface works with all previous software that used it. I need to determine how to piggyback the flash (SDCard Interface over top of that) I have some ideas which I have been kicking around for a while. I will document those in my next post. I would certainly welcome any feedback on that info when posted.

 Over and out

 Glenn

One Response to “There’s only one way to go and that’s forward ….”

  1. Nick Westgate Says:

    Sorry to hear about your loss. The Real Stuff in life can slow us down at times, but not forever …

    Cheers,
    Nick.

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