[vcf-midatlantic] Random numbers

Bob Applegate bob at corshamtech.com
Sat Apr 8 13:16:14 EDT 2017

> 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.


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