Processor Interface

Got a question Guys!

I'm diddling with a Z80 CPU with a half-baked idea of building a low budget Z80 computer (one of the many shiny things that keep from me from completing much of anything :-( ).
The question... While testing, I'd like to use a Basic Stamp to supply the Z80's clock frequency. Can I output a BS2 waveform directly to the Z80 clock pin or would I need some same of interface?

Thanks for any wisdom!

@
Founder of the "Society for Aimless Tinkering and World Conquest"

Comments

  • 6 Comments sorted by Date Added Votes
  • Directly from the Stamp to the Z80 should be fine. Running it to other chips increases the loading so at some point a clock driver will be needed.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • It sounds a fair idea. I think the z80 is still an incredibly capable chip, especially with the cmos 20MHz variants. There seems to be a few projects out there for z80 based single board computers. I have a few of the early maplin boards. I suppose you could use a signal generator set to square wave, but a stamp is an awful lot cheaper.
    I'm interested to see how you get on.
    regards john
  • One problem with the Stamp is that it does not have a command that will output an arbitrary square wave frequency. The FREQOUT command generates a sine wave (based on PWM).

    What frequency do you need? There are so many little packaged oscillators available that cost about a buck, pick your frequency. And doesn't the Z80 have a crystal option?
  • One problem with the Stamp is that it does not have a command that will output an arbitrary square wave frequency. The FREQOUT command generates a sine wave (based on PWM).

    What frequency do you need? There are so many little packaged oscillators available that cost about a buck, pick your frequency. And doesn't the Z80 have a crystal option?

    IIRC the original Z80 required an external clock signal. Later versions may have had an on chip oscillator that only required a xtal but I am not certain about that. Too much time has passed.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 20,865
    edited April 25 Vote Up0Vote Down
    The other problem with the BS2 is that there's no command that will output a waveform indefinitely. And doing it by a software loop would be too slow. The Propeller could handle the job easily, though.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • kwinnkwinn Posts: 7,311
    The propeller would be a better choice, and having control over the Z80 clock frequency and all those cogs would be a big help with debugging hardware and software.


    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
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