Re: Technically in school !:)

Andrew Werby wrote:

> Then you could disassemble the software in the EPROM's, and write a new
> software for the original CPU.
>
> [Right. Somebody might be able to do this- but it's certainly not me.]

I did this with my Allen-Bradley 7320, and I suspect at least some people
would call me a computer guru. I don't recommend it for those who are
not REAL familiar with programming minicomputers in machine code
through the front panel switches. My code was originally on paper tape,
but I made an interface to the PC so the PC could read the executive tapes
and then load them into the CNC. I wrote a disassembler for the AB
instuction set, and ended up with a 150 page listing of machine language
instructions with no comments, entry points, subroutine names or variable
names. In fact, you had to decipher the code to even tell what was variable
storage and what was program. The executive software I was able to
obtain didn't match my actual configuration in a number of respects.
The encoder resolution was different, and the executive was for a gantry
bed mill with a 'tandem' Z axis (2 independant Z axes kept synchronized
by the CNC). I had to decipher enough of the code to make these
changes, and it was beastly difficult, because the AB engineers used
self-modifying code, among other tricks, to get around the woeful
limitations of a 1978 minicomputer.

Like I said, unless you are a REAL computer expert, you really DON'T
want to do this!

Anyway, after ALL that effort, I retired the AB, mostly due to poor
performance and unreliability. EMC performs SO much better
(1000 Hz servo updates vs. 100 Hz), and is so much more reliable,
it isn't funny. Technology marches on!

In the 6 months or so I was actively using the AB, I had at least 3
major breakdowns, plus a number of flaky connectors that would cause
front panel buttons to intermittently fail to work and other troubles
like that. Each breakdown took about a day to fix, on average.
Oh, and I had a COMPLETE manual set, with schematics, unbelievably
detailed theory of operation, some troubleshooting info, and diagnostic
programs! Without that level of info, I doubt you would have a chance
of deciphering the code, figuring out the hardware, etc.

Jon