Re: A83: Re: Random number
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Re: A83: Re: Random number
In a message dated 29/02/00 17:33:04 GMT Standard Time,
gte172i@prism.gatech.edu writes:
<< ld a,r ; 0-255
and %1 ; 0 or 1
;the value isnt very random but it is better than nothing. >>
I do not believe this is reliable. R is incremented on every instruction
byte fetch but certainly for some Z80 processors only bits 0..6 are
incremented, bit 7 says the same and can be altered by LD R,A.
Also, because this is tied into a cycle count if you are running code
which has a fixed number of T-States each time.
e.g.
repeat
pos = Random(16)
until not Used[pos]
because for each iteration of the loop the number of t-states does not
vary then it is not impossible that pos could generate either a repeating
value or a repeating sequence of values which would cause the loop
to lock up.
Paul Robson.
... and when you write a spectrum emulator these idiocies do actually
matter :)