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Re: [cosmacelf] 6C opcode = INP 4 or INP C?

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  • Lee Hart
    ... It will depend on your assembler. If an equate sets C=4, then they are the same. The assembler I use (Avocet XASM18) also accepts INP4. -- Lee A. Hart |
    Message 1 of 3 , Jun 3, 2011
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      On 6/3/2011 3:17 PM, whd_whd_whd wrote:
      > I'm yet again re-acquainting myself with the 1802 opcodes and instruction set.
      >
      > I wanted to make sure I get this right.
      >
      > Is the Input opcode 6C supposed to be shown as
      >
      > INP 4
      >
      > or
      >
      > INP C

      It will depend on your assembler. If an equate sets C=4, then they are
      the same.

      The assembler I use (Avocet XASM18) also accepts INP4.

      --
      Lee A. Hart | Ring the bells that still can ring
      814 8th Ave N | Forget the perfect offering
      Sartell MN 56377 | There is a crack in everything
      leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
    • Richard
      The processor has three N lines to encode the selected port. This would normally provide for 8 input and 8 output ports. The 60 and 68 instructions are
      Message 2 of 3 , Jun 3, 2011
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        The processor has three N lines to encode the selected port. This would normally provide for 8 input and 8 output ports. The 60 and 68 instructions are reserved or used for different purposes, so only 7 input and output ports remain.

        Officially, those are INP 1 to INP 7 and OUT 1 to OUT 7, matching the values on the N lines. Some assemblers, however, may allow you to use INP 9 to INP F instead. Personally I would not use this notation to keep my sources more readable and not run into troubles when using another assembler.

        --- In cosmacelf@yahoogroups.com, "whd_whd_whd" <whd_whd_whd@...> wrote:
        >
        > I'm yet again re-acquainting myself with the 1802 opcodes and instruction set.
        >
        > I wanted to make sure I get this right.
        >
        > Is the Input opcode 6C supposed to be shown as
        >
        > INP 4
        >
        > or
        >
        > INP C
        >
        > ???
        >
        > I think it's the former, but right now I have it as the latter,
        > and I have seen it both ways.
        >
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