Re: Computing Editorial (please read)

[Lee Hart <leeahart@earthlink.net>]

>> You misunderstood. The "Elf" was a complete computer; like an Apple
>> II, it included not only the computer itself (CPU, memory, I/O) but
>> also the front panel switches and/or keyboard, hex LED display
>> and/or video, cassette storage, power supply, expansion slots, etc.

Michael Joosten wrote:
> Lee, I hope I did not... most of the MCU designs for hobbyists
> nowadays probably use a serial port to communicate with a small
> monitor program, or just use some parallel PC port to program
> their internal flash ROMs

My first concern is that there aren't any MCUs designed for beginning
hobbyists. The ones that do exist assume you are already a knowledgeable
engineer or trained technician, already have a PC, and are already
familiar with computer programming languages.

That's fine for you and I; we already learned this stuff thanks to years
of experience that started on our first little computers years ago. But,
how do the students of today get started? 

> it should be quite trivial to add 6 seven-segment displays (or
> standard LCD display) and a small keyboard to arrive at a small
> standalone system, like the KIM 1, SDK-85, Microprofessor-1, etc.

Is it? Let's pick some small microcontroller board, like the Parallax
BASIC Stamp 2 for $49. A 4x4 matrix keypad will be about $10, and can be
interfaced using 8 of the 16 I/O lines. But a little 16x2 LCD display
will add another $49. We could use six 7-segment LEDs and a 74LS145
decoder; that would cost about $10 but now we've used up all our I/O
lines.

But, no one has written any software to use this keypad and display;
there's no monitor program, much less anything like Tiny BASIC. So, we
would also have to buy the development kit for $150. And this
presupposes we have a PC. We're back to a setup worthy of a professional
engineer, and that will require an experienced programmer to use it.

> Yes, that's also how I started, with the Junior from Elektor, a KIM
> variant of 1980(6502, 6532, 1KB monitor, 1KB RAM, later with an upgrade
> for cassette, serial, addt. 1KB RAM, 2KB Tape Monitor, 2KB Printer
> Monitor and a 6522), which I still have (of course!).
> 
> To go as 'low' as just having eight switches with some counters to
> increment the addresses and the like was ... a bit too early for me,
> though such a beast also appeared in Elektor in '77, IIRC, based on
> NatSemi's SC/MP. Interesting, but a little too expensive as
> birthday/christmas present for a 14 year old.

The "Elf" I started on was certainly under $100 then, and wouldn't cost
even $50 now. The earliest ones had toggle switches and LEDs for I/O;
the later more advanced ones had hex keypads and a video output for a TV
set. Wasn't the KIM-1 about $150? I think all of the single-board
self-contained trainers were in the $50-$300 range (and that was for the
complete system; nothing else needed except possibly a TV set or
cassette tape recorder).

> Well, a PC has become a commodity device - so it does not really count
> in this calculation.

Only among certain classes of people. What percentage of homes do you
think have PCs? Even in the USA, it is less than 1/4. And normal "old
fashioned" serial and parallel ports are gradually being eliminated from
new PCs.

>> You probably *could* build a standalone computer with a PIC, AVR, or
>> 8051-series micro; but nobody does!

> Not sure about PIC, but I'm pretty sure about the others. And I would
> be surprised if nobody has already done this with at least the 8051,
> as they are older than the other MCUs.

I'm sure they used to exist for the 805x series. But, I fear they are
all gone now.
-- 
Lee A. Hart                Ring the bells that still can ring
814 8th Ave. N.            Forget your perfect offering
Sartell, MN 56377 USA      There is a crack in everything
leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen