16 Jul
2001
16 Jul
'01
3:09 p.m.
While there are a lot of processor-application-related
things you are
prevented
from, or at least, restricted in, accomplishing because of the restrictions
placed on the hardware by the design of the platform, there certainly isn't
anything you can't do from a computing standpoint. However, that was my
point.
The things that define a microprocessor-based system are fixed in the Apple,
mostly by its video timing restrictions, but also by its memory map and
the way
in which I/O is managed.
ONLY if you restrict yourself entirely to the Apple II hardware. Anything I
couldn't directly do internally on the Apple I could put on a protocard and
just use the Apple as a convient disc drive and display.
There's no question that one had to read quite a
bit. However, most of the
materials written about microprocessors were really dedicated to
microcomputing
rather than the application of microprocessors. Device manufacturers
weren't of
much help either because they wanted you to buy their particular development
systems, with their limitations, and those didn't often help very much.
What I was refering to in books were timing diagrams, not how to write a
new version of CheckBook. My work in embedded control was as much about
gate delays as gosubs. I never ran into the "restrictions" and found the
Apple II a very convient platform to develope from. A 6520 on a cheap Apple
II I/O card doesn't behave very differently from the same chip on a
protoboard as part of a 6502 based controller. Many many apples crossed my
bench and sat on my desk with a loom of wires trailing out the back to
simulate some process before the "real" boards were ready.