[vcf-midatlantic] Random numbers

Dan Roganti ragooman at gmail.com
Sat Apr 8 22:41:34 EDT 2017


On Sat, Apr 8, 2017 at 1:16 PM, Bob Applegate via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

>
> > On Apr 8, 2017, at 1:06 PM, Dave McGuire via vcf-midatlantic <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> >
> > On 04/08/2017 12:10 PM, Dan Roganti via vcf-midatlantic wrote:
> >>> ​Remember,
> >>> that step to seed the rnd generator is not perfect either​
> >>> ​
> >>> ​, eg. RND(-32768) or whichever value​
> >>> ​if you use the same seed, guess what,
> >>> you get the same random numbers :)
> >>
> >> ​This is why you like to use something "random" to seed the rnd
> generator​
> >> Usually every computer has a free running counter,
> >> meaning it's constantly being updated in the background
> >
> >  If some of my dustiest neurons are working, in the Atari at least
> there's a scan line counter from the video subsystem available for
> reading.  At least I think it was something like that.  That was great for
> seeding random number generators.  The Apple ][ must have something like
> that.
>
> Or just use a software “timer”, like the delay until the user does
> something, like move the joystick, press a key, etc.  Ie, sit in a loop
> waiting for something to happen, incrementing a counter each time through.
> When the user finally does something, use the counter as a seed.
>
> Another option is to just sum up all of RAM memory since it’s unlikely
> exactly the same thing will be in every memory location each run.
>
> Bob
>
>

​ok this is getting more weird,
both McGuire's and Applegates post just arrived to my inbox and they were
written & sent 9 hrs ago
I'm wondering if my post at 1:14pm came thru​ ok
the link in there has a nice writeup about this topic from a lab experiment
from 1987
Dan



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