[vcf-midatlantic] Random numbers

David Riley fraveydank at gmail.com
Sun Apr 9 06:54:50 EDT 2017


On Apr 8, 2017, at 13:06, 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.

Hahaha, NOPE. The Apple II is EXTREMELY Spartan hardware. There's not even a timer in there. The only hardware you can count on is RAM, some ROM, the (0 or 1 valued) cassette interface, and some miscellaneous stuff (speaker output, paddle connector, etc.).

Getting good entropy to seed is hard on an Apple II.


- Dave



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