Re: Z80 Assembly books related to CP/M - CP/M

This is a discussion on Re: Z80 Assembly books related to CP/M - CP/M ; > Message-ID: roche182@laposte.net wrote: > No: it was the Z-80 which was compatible (except the famous NMI > falling at 0066H, in the "Page Zero" of CP/M... You will notice that > NOT ONE CP/M system ever used the Z-80 ...

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Thread: Re: Z80 Assembly books related to CP/M

  1. Re: Z80 Assembly books related to CP/M

    > Message-ID:

    roche182@laposte.net wrote:
    > No: it was the Z-80 which was compatible (except the famous NMI
    > falling at 0066H, in the "Page Zero" of CP/M... You will notice that
    > NOT ONE CP/M system ever used the Z-80 NMI!) with "CP/M-compatible


    The Acorn Z80 Second Processor both ran standard CP/M *and* used
    the NMI. On an instruction fetch from &0066 the ROM is temporarily
    paged mapping in a JP instruction to the NMI code in high memory.
    Many other Z80-based systems that ran CP/M did a similar thing.

    > are already taken by the 8080, so the Z-80 opcodes are, inherently,
    > slower than 8080 opcodes. In addition, Zilog was slow to release any


    Hmmm....

    Z80: ADC HL,BC
    8080: LD A,L:ADC C:LD L,A:LD A,H:ADC B:LD H,A

    > assembler? It was tape-based...). Also, the indexed IX and IY opcodes
    > are 1) not documented,


    Look in the documentation...

    > 2) badly designed, as I discovered when


    Very neatly designed. Just prefix an HL instruction, and it
    becomes an indexed instruction. Just toggles a latch inside the
    CPU.

    > disassembling ZSID. Finally, from a technical viewpoint, you need TWO
    > LINES per opcode to display what is happening to the registers. That


    Eh? I'm lost there.

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    J.G.Harston - jgh@arcade.demon.co.uk - mdfs.net/User/JGH
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  2. Re: Z80 Assembly books related to CP/M

    Jonathan Graham Harston wrote:
    > roche182@laposte.net wrote:
    >

    .... snip ...
    >
    >> disassembling ZSID. Finally, from a technical viewpoint, you need
    >> TWO LINES per opcode to display what is happening to the registers.

    >
    > Eh? I'm lost there.


    See how DDTZ does it. Normal display is just one line. A command
    is available for the second line. See:



    --
    [mail]: Chuck F (cbfalconer at maineline dot net)
    [page]:
    Try the download section.



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