Re: A86: a question
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Re: A86: a question
>>>like ld de,(ix+hl)?
>>
>>ex de,hl ; 1 cycle, 4 T states
>>add ix,de ; 4 cycles, 15 T states
>>ld e,(ix) ; 5 cycles, 19 T states
>>ld d,(ix+1) ; 5 cycles, 19 T states
Could someone please explain what "T states" mean in relation to Z80
processor speed? I looked it up in the Z80 reference book from Zilog, but
it didn't explain it.
I've never seen "T states" or anything like that when "counting cycles" for
the PC (which varies greatly from processor to bus to cache), so does it
have to do with bus i/o "cycle eaters"?
Please confirm this understanding: a microprocessor's MHz is how many
million cycles it executes per second...a 6 MHz processor like the TI-86's
runs 6,000,000 cycles per second. An instruction that executes in 5 cycles
could be executed 1,200,000 times second. But this seems a little too fast
for the calc, but not my 50 MHz 486.
Lastly, the R (dynamic memory refresh) register would be incremented
automatically by how many cycles the current instruction takes, right? Is
this why, when executed in a loop, it would give a pattern of "random" numbers?
Thanks,
David Phillips
electrum@tfs.net
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