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Embarrassing MHz question....

KorinelKorinel
edited April 2012 in Emulators
(Hangs head in shame; you may throw tomatoes and mouldy fruit at me.)

What is the standard speed (exact please!) of the Z80 CPU in a 48K ZX Spectrum?

I see 3.5 MHz and 3.54 MHz on the internetz and I don't know which "speaks the truth!"
:???:
Post edited by Korinel on

Comments

  • antoniovillenaantoniovillena
    edited April 2012
    3.5Mhz

    3.5Mhz from a 14Mhz crystal. 128K models runs at 3.5469 Mhz because use the same clock font to generate the 4.43 Mhz pal subcarrier.
  • KorinelKorinel
    edited April 2012
    Thank-you!

    ZXSpin v0.7 and SpecEmu v3.0 both imply they have the speed of a 48K Spectrum at 3.54.....
  • ArjunArjun
    edited April 2012
    Korinel wrote: »
    ZXSpin v0.7 and SpecEmu v3.0 both imply they have the speed of a 48K Spectrum at 3.54.....

    Really? Where? 3.54 true for the 128k as Antonio said.
    Zero - A modern Spectrum emulator for Windows.
    Bytes:Chuntey - Spectrum tech blog.
  • KorinelKorinel
    edited April 2012
    Arjun wrote: »
    Really? Where? 3.54 true for the 128k as Antonio said.

    You make it sound like I'm clueless Mr Arjun, it's very easy to check...

    Spin:

    Tools -> Options -> Hardware -> Spectrum Model -> 48 K
    Emulation -> Z80 CPU Speed = 3.54MHz

    Spec Emu:

    Options -> Model -> Spectrum 48K
    Z80 -> CPU Speed -> 3.54 MHz
  • ArjunArjun
    edited April 2012
    Heh. That wasn't what I was implying at all. I was just being lazy because to check I would have to start up XP on Vmware on my Mac. ;)

    But yes, you are right. I can only imagine that it's because that UI is common to both the 48k and the 128K models but why 3.54 was chosen was over 3.5 is a mystery. :)
    Zero - A modern Spectrum emulator for Windows.
    Bytes:Chuntey - Spectrum tech blog.
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