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

  • 10 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: 20,920
    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
  • 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.
  • Just in the testing phase right now. A clock frequency somewhere around 1kHz-ish would be fine.
    I only thought of using the Stamp cuz I'm too lazy to wire up a 555. :-|

    @
    Founder of the "Society for Aimless Tinkering and World Conquest"
  • ercoerco Posts: 17,825
    edited April 27 Vote Up0Vote Down
    ajward wrote: »
    Just in the testing phase right now. A clock frequency somewhere around 1kHz-ish would be fine.
    I only thought of using the Stamp cuz I'm too lazy to wire up a 555. :-|

    Stamp: $50
    555 timer: 4 cents http://forums.parallax.com/discussion/comment/1393138/#Comment_1393138

    Just sayin'.
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • I have a little stack of SMT 555 breakouts prewired as square wave generators which were shipped by mistake when I ordered a set of HX711 ADC breakouts. When I informed the seller of the mistake they went ahead and sent me the HX711's and said keep the 555's.
  • ercoerco Posts: 17,825
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
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