[....]
I am also old enough to have worked on the design of bit slice
computers, printed out my listings on a teletype, input my code on
paper tape, and write programs on punch cards that were sent away to
the computer.
You ain't the only one. Never got to build my bit slice machine
though. Strange, it influenced the design of many machines along the
way.
*my* bit slice didn't get built. Somebody else's did. I also
consulted to someone building a 3rd one that I can't go into.
I also did a machine that was a lot like a bit slice that didn't
really have an ALU. It was a system that needed to read a bunch of
bytes from memory and rearrange the nibbles quickly. The idea of
using a registered PROM and a counter to make logic signals has popped
up many times.
Ahhh. Primitive state machines. Another useful tool that has been
around a while. Some of the current tools for state machines help you
set up multiple interacting state machines. Now that can be fun.
The project I am working on has multiple state machines in the micro.
They still make a great way to arrange the problem to be solved.
Some years back, these guys showed up trying to sell a state machine
based product development tool for products. It was a very clever
scam. Among their claims was that their product output C code that
was 100% if your design was correct in their tool. When I got into
the details, I discovered that to develop you wrote stuff like:
if (some expression) tra-la-tra-la {
Some code to do tra-la-tra-la
}
they then ran using that code. When it came time to output, they just
had to strip out the "tra-la-tra-la". I spent a weekend and made a
more useful tool. Their's required you to basically write your
application before you could show what it did to marketing. Mine made
a very quick fake up of the user interface with a lot less code.