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re: membership card

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  • ml_ven
    Why not just the following on a small board: 1802, oscillator, addr latch, 32K ram (nvram or flash), and connector on one small board. then on a daughter
    Message 1 of 116 , Jan 28, 2005
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      Why not just the following on a small board:

      1802, oscillator, addr latch, 32K ram (nvram or flash), and connector
      on one small board.

      then on a daughter board:
      the logic for the i/o (including the leds, dip switch), run, load, MP
      and IN sw), and possibly the IDE interface

      or on a second daughter board:
      logic for RS232 i/o, or video or whatever

      or on a different daughter board:
      logic for expanded i/o.

      or ...

      The whole lot could be stacked and possibly less than 2 x 3 x 2
      inches in total volume.

      Mike V.
    • ajparent1
      ... Lee, they run the gamut from cmos parts in the few mils range to around 100ma for the older nmos designs. I have some Alliance CMOS parts pulled from a 486
      Message 116 of 116 , Feb 27, 2005
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        --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@e...> wrote:
        > One more thought. Can someone who has any of the skinny-DIP 28-pin
        > thru-hole 32k RAMs actually plug one into a breadboard and see how much
        > power they really take? If we can find one that is reasonably
        > inexpensive and available, we could use it on the MEMBER card to save a
        > chip.

        Lee, they run the gamut from cmos parts in the few mils range to
        around 100ma for the older nmos designs. I have some Alliance CMOS
        parts pulled from a 486 cache and they run about 12ma when supporting
        a z80/4mhz. Their drain is cycle time dependent for the cmos. I've
        looked and the general xx256 parts are still fairly easy to find and
        cheap. Do watch for the parts that are semi-static where the address
        lines are latched by CE/. Their power drain is very low but CE/ must
        be asserted for every access.

        Allison
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