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  • Butterfly
    Butterfly
    Jeckel
    Posts: 96 from 2007/3/11
    Z80@4Mhz is *much* slower that 68000@7Mhz. Maybe 10 times slower (or even worse).

    8x16 bit Z80 multiplication...

    Mul16_8:
    ld b,8
    ld hl,0
    Loop:
    rra
    jr nc,Jump
    add hl,de
    Jump:
    sla e
    rl d
    djnz Loop

    [ Edited by Jeckel 20.07.2017 - 10:24 ]
  • »20.07.17 - 09:22
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  • Jim
  • Yokemate of Keyboards
    Yokemate of Keyboards
    Jim
    Posts: 4221 from 2009/1/28
    From: Delaware, USA
    Quote:

    Jeckel wrote:
    Z80@4Mhz is *much* slower that 68000@7Mhz. Maybe 10 times slower (or even worse).

    8x16 bit Z80 multiplication...

    Mul16_8:
    ld b,8
    ld hl,0
    Loop:
    rra
    jr nc,Jump
    add hl,de
    Jump:
    sla e
    rl d
    djnz Loop


    Yes, it is, and I'm a big fan of the 68000, but really its yet another apples and oranges comparison.
    I can get better multiplication performance out of a Hitachi 6309 at half that speed (and I'm running those at 3.58 MHz in one project). Although...that can only do 8 x 8 multiplication or 16 x 16 multiplication (which obviously could be used for 8 x 16).
    In any case, my point is...comparison of an 8 bit cpu to another 8 bit cpu would be more valid.

    And that's what we have to remember, the Z80 is an earlier 8 bit design intended to compete with Intel's 8 bit cpus.
    Its not fair to compare it to the 68000.

    Edit - BTW, a 68000 processor is what you ADD to a Tandy Model 2 (which already has a Z80) in order to run something more powerful than CP/M, like Xenix. They're known as Model 16s or 6000s. ;-)



    [ Edited by Jim 20.07.2017 - 10:42 ]
    "Magnetic was troubled by my avatars and 'satanic' references" - Jim Igou

    "Never attribute to malice what can more readily explained by incompetence"
  • »20.07.17 - 13:38
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  • Order of the Butterfly
    Order of the Butterfly
    KennyR
    Posts: 235 from 2003/3/4
    From: #AmigaZeux, Gu...
    Quote:

    Jeckel wrote:
    Z80@4Mhz is *much* slower that 68000@7Mhz. Maybe 10 times slower (or even worse).


    Yes indeed, they're just 8 bit CPUs. Even at the simplest a word would require at least two cycles. In practice, most operations used multiple cycles.

    But by 1985, Z80s were often running at 8 MHz, and by the time the CMOS versions came along (I don't know what year), at 20 MHz and up. The original 4 Mhz did 0.58 MIPS raw; the 68000 did just 1.4 MIPs at 8 MHz.

    As a modern comparison, the Raspberry Pi 2's SoC does 4744 MIPS.

    My point was, that the Amiga "super CPU" wasn't quite so super as we believed it was, even in its day.

    [ Edited by KennyR 22.07.2017 - 21:51 ]
  • »22.07.17 - 21:50
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  • Yokemate of Keyboards
    Yokemate of Keyboards
    Andreas_Wolf
    Posts: 9285 from 2003/5/22
    From: Germany
    > The original 4 Mhz [...]

    The Z80 was introduced at 2.5 MHz.
  • »22.07.17 - 22:39
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  • Jim
  • Yokemate of Keyboards
    Yokemate of Keyboards
    Jim
    Posts: 4221 from 2009/1/28
    From: Delaware, USA
    MIPS ratings don't really give you an accurate measure of a processor's relative power when comparing dissimilar processors.
    Especially when considering early microprocessors.

    [ Edited by Jim 22.07.2017 - 18:43 ]
    "Magnetic was troubled by my avatars and 'satanic' references" - Jim Igou

    "Never attribute to malice what can more readily explained by incompetence"
  • »22.07.17 - 23:42
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  • Yokemate of Keyboards
    Yokemate of Keyboards
    Andreas_Wolf
    Posts: 9285 from 2003/5/22
    From: Germany
    > since Minix 3 is still pretty crude, its one I'm avoiding. [...] Pity Minix itself has never
    > been as well fleshed out as some of the process control OS' based on the concept.

    Interestingly, in 2015 Intel‘s Management Engine was switched from running ThreadX on ARC to running MINIX 3 on x86.

    "Starting with ME 11, it is based on the Intel Quark x86-based 32-bit CPU and runs the MINIX 3."
    https://en.wikipedia.org/wiki/Intel_Active_Management_Technology#Hardware

    "MINIX 3 is believed to be used in the Intel ME found in Intel PCH beginning with the introduction of ME 11 which is used with Skylake/Kaby Lake processors."
    https://en.wikipedia.org/wiki/MINIX_3
  • »12.10.17 - 21:15
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