[vcf-midatlantic] Random numbers
Dave McGuire
mcguire at neurotica.com
Sat Apr 8 13:06:21 EDT 2017
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.
Random number generation itself is a fascinating topic and a very
difficult nut to crack. There are multiple large books published about
it. There are financial-industry-quality high-speed hardware random
number generators on the market, used for generating crypto keys. Some
are quite elaborate, using very fancy algorithms to de-bias the number
stream. Some use reverse-biased P-N junctions as their initial source,
and some even use tiny bits of radioactive materials coupled to
scintillation crystals and photodiodes. It's a fascinating field.
Generating true randomness is actually very, very hard.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
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