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My responses regarding random generator.
In response to everyones comments:
I am overwhelmed with all this response that came though
during the times I was absent from the Nets.
At this time, I am evaluating other approaches to this
problem then using the Newbridge system's inflated pricey
It is clear that a simple reversed diode circuit may not be
enough to produce truly random data bits unless care is taken
to prevent periodic signals from being "injected" into the circuit.
Although I don't have access to a "clean lab", I do have
access to Techtronix scopes, and a general HW lab, but not sure
if that is adequate to completly test out the circuit to determine
that things are truly random.
An easy test I often devise is to generate a pair of random
bytes, and display them as X, Y pairs and plot them on the
screen as pixels. First, I start with a clean screen, then
plot the dots as they come in. As these dots are plotted
on the screen, the dots should be evenly distributed over the
screen without "bunching" or "patterns" developing.
I know that this is not the best way to determine true
randomness, but it is cheap and inexpensive to do.
I also agree that we should all check out and determine if
there are other random generators currently available, and
we should compile a list of them to share with the group as
proposed by Tim May. Although I haven't yet visited the
crypt newsgroups, I suspect that I should post a query there
to see if any such puppie exists.
Then, there is the speed of generating these random numbers,
and how we will want to deal with the possibility of inadequate
speed. I suspect that serial transmission at 9500 baud might
be easily obtained, but going much faster withoug "drift" might
be problematic as Tim May pointed out.
At this point, I would now like to get some other feedback
from the group on what Zener noise source to use, and kick
around some design ideas. It would be nice to be able to exchange
schematic diagrams and pass them around. I have a Mac, but
not everyone in this group uses them. So what mechasim can we
imploy to send schematics around?
My next visit to the Nets will be this weekend, so if anyone
wants to contact me, they can try me at (510) 769-1268, and
it will refer to the number where I'm staying at that time.
I still have NO permenent home (after long period of unemployment),
so getting on the Nets daily will be problematic for me.
I usually hang out in South San Jose, at my friends VCR Repair
lab (where this hardware equipment is located), but have no computer
set up there until we can set up proper physical security. That
number is (408) 377-2382. I am usually there early in the week,
because I can make calls to find work from there on Mondays.
As I converge into a workable design and if the lab results
are encouraging, and acceptable to the group, I would like to
build 2 or 3 prototypes and pass them around to volunteers for
Beta testing before making them available to the group as a whole.
I can get PC boards made via Douglas Electronics fairly
inexpensivly, and plan on making them as orders come in, and
initial setup costs would be about $350. I already have
people set up to invest this much already.
Perhaps it would be prudent to set up a group of other HW
designers and meet physically somewhere to hammer out a design
and make this a group effort. Do I have any volunteers?
I think only one meeting would be necessary to determine a rough
approach to take.