Erik,
You might try incrementing one of the timers every so often. Maybe during
vblank. Hmmm...decrementing would work better. In case the timer happens
to be zero, it wouldn't always give a value of zero when you read it. I don't
have any docs here at work, so I don't know if this is feasible. I don't
think you can actually use the DEC instruction, because the timers are write
only. Not sure on this. If so, the code below only costs 12 proc cycles, I
think.
...
...
LDA INTTIM ; get timer value
SBC SEED ; subtact preset seed value. don't care about carry.
STA (timer) ; store new value in timer of your choice
...
...
>
> Any hints on how to go about creating a pseudo-random number generator on
> the 2600? True random numbers seem pretty difficult if not impossible (as
> with most assembly languages), but one can get a seed and plug it into an
> algorithm to get pseudo-random numbers. On the PC, it's easy to use the
> current time for the seed (all BASIC programmers know RANDOMIZE TIMER), but
> that's not there on the 2600.. anyone have a good method for getting a seed
> and/or a good algorithm that works well on the 6502? thanks!
>
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