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Re: RCA COSMAC Microkit

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  • joshbensadon
    ... I don t think Bill has determined that the bus is inverted. I observed the dump that Bill posted didn t make sense as 1802 machine code until I guessed
    Message 1 of 13 , Apr 18, 2013
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      --- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:
      >
      >
      > >
      > > In this case, if you had an inverted bus, it would make sense to store
      > the ROM as inverted so you didn't have to put another buffer chip on the
      > bus. If you're trying to disassemble it, just run it through a program to
      > flip the bits.
      > >
      > >
      > -Thanks Dave-


      I don't think Bill has determined that the bus is inverted.

      I observed the dump that Bill posted didn't make sense as 1802 machine code until I guessed that the bits might be inverted.

      I am only guessing that the bus is inverted and wish to advise Bill to look out for that.

      I could be totally out to lunch, since it is an 1801 chip set.

      :)J
    • B Degnan
      When I get back from a brief vacation I will look up the commands from their HEX values, and/or convert to an Intel record that would be easier to assemble. I
      Message 2 of 13 , Apr 19, 2013
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        When I get back from a brief vacation I will look up the commands from their
        HEX values, and/or convert to an Intel record that would be easier to
        assemble. I believe I have the instruction set in my
        vintagecomputer.net/RCA/COSMAC directory, or elsewhere. If assembly is
        possible. No way to know about whether inversion is necessary yet.



        -----Original Message-----
        From: midatlanticretro@yahoogroups.com
        [mailto:midatlanticretro@yahoogroups.com] On Behalf Of joshbensadon
        Sent: Thursday, April 18, 2013 1:39 PM
        To: midatlanticretro@yahoogroups.com
        Subject: [midatlanticretro] Re: RCA COSMAC Microkit

        --- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:
        >
        >
        > >
        > > In this case, if you had an inverted bus, it would make sense to
        > > store
        > the ROM as inverted so you didn't have to put another buffer chip on
        > the bus. If you're trying to disassemble it, just run it through a
        > program to flip the bits.
        > >
        > >
        > -Thanks Dave-


        I don't think Bill has determined that the bus is inverted.

        I observed the dump that Bill posted didn't make sense as 1802 machine code
        until I guessed that the bits might be inverted.

        I am only guessing that the bus is inverted and wish to advise Bill to look
        out for that.

        I could be totally out to lunch, since it is an 1801 chip set.

        :)J




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