Apple II for intro to microprocessors

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Jul 17 10:55:14 2001

I was one of those who went for the AIM-65 when it came out, but found it too
limiting because of its "features" and facilities. It seems that the more
facilities a system provides, the less flexibility one has in its use.

I stand by my previous comment, namely, that the single-chippers with a built-in
or programmed-in monitor offered a better solution to the problem of
LEARNING/EXPERIMENTING with microprocessors than did either the Apple or the
AIM-65 or other devices of that sort. Hindsight's always 20/20, as they say,
and I base that comment on the fact I've been able to figure out more things
with a single-chip device that could be adapted to a task without hindering its
I/O capabilities, yet didn't have to be slaved to the I/O either.

Your comment about the FDD's is right on target, Mike. That's why so many
people used the Apple][ for development. Writing an OS for the AIM or something
of that ilk, or, for that matter, for a single-chipper, would have been a
serious pain, and, for most of us, unlikely to happen.

However, with a ROM-resident debugger and line-by-line assembler, it was
possible to get quite a bit done. The LILBUG monitor, which is what was built
into the ROM on a 6801L1, as an example, had a reader and punch function, which
could be used to dump to an audio tape interface, though I personally never used
it in that way. It could also be used to dump to a serial port, and, with a
host system that used its console as a terminal to the single-chipper, you had
lots of options where lodaing and saving code were concerned.

The Lilbug monitor has the option of allowing its console function to be routed
through an external serial port at a user-defined location, and to use an
external counter/timer chip as well, though I'm not sure why except perhaps to
free the internal faciliites for development use. Routing the console to an
external ACIA (MC6850) is helpful when one is developing an application that
requires the presence of the internal serial port and counters. It does, of
course, place restrictions on what one can do, but I find that a small price for
the added funcitonality in cases where it's needed. It's the same way with the
Apple hardware environment. If you want the functions, you have to put up with
the associated restrictions.

It certainly wasn't difficult to use a CP/M box to send a block of code to the
resident monitor on the single-chipper. Back then I used cross-assemblers under
CP/M (this was before the rise of the PC) to support those efforts. Using a
monitor that had the capability merely to dump a block of binary code translated
to ASCII-HEX to the console was enough to enable the file to be saved on a host
system.

That rendered the use of a dedicated develpment system with in-circuit emulator
unnecessary, though not totally without potential merit.

Dick

----- Original Message -----
From: "Mike Ford" <mikeford_at_socal.rr.com>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, July 16, 2001 10:01 PM
Subject: Re: Apple II for intro to microprocessors


> >There's no doubt about it, Mike, the Apple was quite useful for a lot of
> >things.
> >I simply pointed out that with a different device, costing about $90
> >rather than
> >the considerably more that an Apple][ cost back in '79, you could do much
> >of the
> >same stuff, unfettered by the restrictions that the Apple hardware put on
you.
>
> Sure, BUT my first programming was on a AIM65 with backup to cassette. An
> Apple II cost me close to $5000 vs the $500 or so for the AIM65, but having
> floppy drives made it worth every penny. Now the tables are turned, and
> Apple IIe is maybe $5 and the AIM65 $50 or $100.
>
>
>
Received on Tue Jul 17 2001 - 10:55:14 BST