Microtutor II: a modern microcomputer trainer
- Mark Graybill wrote:
> Thanks, Lee.Mark, I think you've done very well! If the goal is to teach beginners
> It's not an Elf, but I'm trying to keep it as simple as possible...
about computers, it has to be a very small, simple, straightforward,
almost trivial system. It needs to teach the basics quickly, so students
don't get bored. Yet it needs to be rich enough so they can continue to
learn and grow. And, it can't be too far out from mainstream computing,
or what they learn won't be directly applicable to 'big' computers.
In brief, they want to climb the ladder quickly; climb high, and they
want it to get them where they want to go.
I've given this matter a lot of thought. I'm concerned that today's
computers are so complex that beginners never learn the basics. And
without a solid foundation, their solutions are overly complex,
expensive, and unreliable. Charles Moore (inventor of FORTH) said, "I
despair. Technology, and our very civilization, will get more and more
complex until it collapses. There is no opposing pressure to limit
The original RCA Microtutor is what got me started. It inspired the
Popular Electronics ELF, and all that followed. Like your 8085 trainer,
it was so simple that beginners could build it, understand it, and
expand it considerably. For example, adding video with just one chip
(the 1861). Or adding a couple memory chips, and having a high level
language (Tiny BASIC).
But due to the technological limitations at the time, it was hard to
expand the ELF beyond a certain point. Serious amounts of memory, decent
video, or mass storage required many expensive chips. Higher level
languages (Pascal, C) were unavailable or very expensive.
I think it would be enlightening to consider what a modern
Microtutor/ELF might look like. Big memory chips are easy to get, but
peripherals are still a problem. A PC keyboard is easy, but the software
to make it work is hard. There aren't any single-chip video systems that
I know of. There are disk controller chips, but they aren't easy to
Two ideas come to mind. One is to use preprogrammed single-chip micros
to simulate the desired peripherals. Yes, it's are a micro; but treat it
as if it's a piece of hardware.
Another is to use a serial bus to tie the various chips together. This
vastly reduces the number of lines a beginner has to wire. There are
serial memories, serial I/O chips, etc. So I can envision a computer
that consists of a few 8-pin DIPs -- one emulates the 1802, one is the
nonvolatile memory, and one has the video output and PC serial keyboard
Software: I know C and Java are currently in fashion, but I don't see
them as good beginner languages. I'd rather see something like BASIC,
FORTH, or Logo. Logo's strength is that it is specifically meant for
beginners, and a lot like modern programming languages. FORTH's strength
is that it is excellent for I/O intensive applications. Charlie Moore's
ColorFORTH has a lot of interesting ideas that could be used.
Lee A. Hart | Ring the bells that still can ring
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- I think someone already did that. But I don't think they finished it.
They were going to do an 1861, on-chip, too.
And one of the PIC or Arduino clones runs pretty fast, if I'm
It's really not that hard to simulate an 1802. Harder to fully hardware
Getting all of the low-level signals to work like an 1802 is a challenge.
If you need that low-level compatibility.
If it more or less runs the software, and that's all you really care
about, then that
makes it a bit easier.
You could use any modern (-ish) CPU and probably create a really fast 1802.
If you used a 68000, or older intel, or fast Z80, or maybe 8085,
something like that,
you should be able to make a pretty zippy 1802.