Re: 14MHz Osc Chip Question

[mjmahon@aol.com (Michael J. Mahon)]

Bryan Parkoff asked:

>    I seem to understand, but you did not answer my question.  What do clock
>pulse and cycle mean?
>
>    I understand that Hertz is the same as Cycle.  Hertz only executes each
>one second.  It is what the dictionary said, but it is probably wrong.  If
>it is possible, Hertz is truly to be executed each one millisecond.  It
>should be .001 cycle each one second.  It would be 1,000,000 cycles per
>second or 1MHz.  Minimum 142,857 instructions are executed each one second.
>Maximum 500,000 instructions are executed each one second.  Average 222,222
>instructions between 142,857 and 500,000 instructions are executed each one
>second.  Does it make sense?

One Hertz is one cycle per second.  "Cycle" is a full period of a waveform,
with no information about frequency at all.  "Cycles per second" is a measure
of frequency, also known as "Hertz".

The clock waveform of an Apple II (like most digital electronics) is
approximately a square wave, at a frequency of approximately
1MHz, or 1 million cycles per second.

Your calculations of the minimum and maximum instruction rates for
a 6502 running at 1MHz are correct (for 7-cycle and 2-cycle instructions,
respectively.  The average rate is, however, not easily known, since it
depends on the dynamic mix of instructions executed, and that varies
quite a lot from moment to moment and program to program.

-michael

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