Amen on programming being much more fun as a hobby. :> I also miss the old 8-bit machines; the last computer I worked on which I felt like I understood completely was the Atari 800 XL. I can still name a few key page-0 addresses off the top of my head.

And even with a d-(power of two), you might not catch it depending on how it's used. If e.g. each generation sequence used a d8 seven times, the repetition would "walk" through the sequence of fields in a way that might be hard to spot.

I wrote a rand() visualizer on the ][ that started at the center of the screen, and then drew a short line in one of the cardinal directions based on rand % 4, then did the same from the new point. The repeated pattern on the screen made the issue pretty obvious.

On Mon, Oct 17, 2016 at 1:44 PM, Bruce Johnson <xxxxxx@pharmacy.arizona.edu> wrote:
Hmm, that’s how I managed to miss it, I think, I did not check D4 or D8, just D6 and D20 which were not powers of 2. Also I’ll admit I didn’t look at patterns, but when I ended using the functions in my programs I don’t recall patterns coming up all the frequently. This was for a random dungeon generator, a character generator and some cool terrain-building stuff.

I’ll admit though, the pinnacle of my Apple II programming, at least in terms of popularity was “triangles!” which simply generated random triangles on the screen when a key was pressed. Kept our friend’s 4-year-old fascinated for hours. 8-)

I had much more fun programming computers BEFORE I did it for a living... :-/


> On Oct 17, 2016, at 1:34 PM, C. Berry <xxxxxx@gmail.com> wrote:
>
> The distribution was good if you just did mod-6 to get a die roll, but there were serious problems with patterns in the lower bits. If you did mod-(small power of two) you'd very frequently get a short repeating cycle, e.g. mod-4 producing (0, 3, 1, 2, 0, 3, 1, 2, 0, 3, 1, 2...) ad infinitum.
>
> On Mon, Oct 17, 2016 at 1:26 PM, Bruce Johnson <xxxxxx@pharmacy.arizona.edu> wrote:
>
> > On Oct 17, 2016, at 1:10 PM, Kelly St. Clair <xxxxxx@efn.org> wrote:
> >
> >  And when computers WERE brought to bear on the issue, the programs used were primitive and error-prone; consider the first Atlas of the Imperium, and its notoriously bad dataset, with whole sectors of bad output.
>
> That was fixable even then; the Apple BASIC RAND() function was actually pretty good.  (iirc an Apple II was what was used to generate the Atlas) IF you didn't commit the rookie error of re-seeding it with the same value every time :-/ Also I do believe that someone sold a card that sampled background radiation for a true random seed. I know I considered getting one at one point, just couldn’t justify the $150-ish cost.
>
> I did a bunch of rand() testing with my ][+ back in the day; I repeatedly ran out to (iirc) 500,000 rolls of 2 and 3D6 and got a nice smooth distribution curve that looked properly bell shaped. Took 4 or 5 hours to do each set, of course. A 1kHz clock speed’ll do that for yah :-)
>
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> Information Technology Group
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