kits, definitions, prices...

From: Bill Yakowenko <yakowenk_at_cs.unc.edu>
Date: Wed Oct 7 16:55:02 1998

Hey, several threads just coalesced in my head. (Ouch!)

There are a handful of questions that keep getting re-hashed.

        Build my SwTPC kit and play with it, or treasure it in pristine form?
        
        Is my LSI-11 a micro, or not?
        
        Are my XT's really classic?
        
        Should I hack my Apple-1 to sub in a 99 GHz Pentium for the 6502?

        Wanna buy a 1200 baud modem?


The problem is that we have so many different backgrounds and goals,
everybody has different answers to those.

So, when these questions come up, maybe instead of arguing about the
right answers, we could gain more by digging backwards to the *reasons*
for the different answers.

Here are my two cents:

Most of my stupid sample questions revolve around differing valuations.

        Sources of value.
                1. Nostalgia
                        I had/wanted one of these once.
                2. Education
                        This is really different from stuff I already know.
                3. Preservationism
                        There are only three left on the entire planet.
                        If I don't protect it, soon there won't be any.
                4. Usability
                        I make practical use of it.
                5. Money
                        There are only three left on the entire planet.
                        Somebody must be willing to pay a lot for it.
                .. any more?

So building a Heathkit is good for reasons 1, 2, and 4; and bad on 3 and 5.

In my own collection, different items hit different buttons. I play
games on my Radio Shack Color Computers, so they hit button 4. I also
hack around in machine code on them, so they hit button 2. And I've done
quite a bit of work with 6809's, so they hit button 1 as well. (No wonder
I have such a pile of CoCos!) My SwTPC kit is still unbuilt for reason 3.
It doesn't hit buttons 1 or 2 so hard because I also have an assembled one
which covers those nicely. (Man, I'm a lucky guy!) And it seems my own
button 5 isn't connected to anything. But other peoples' seem to work
just fine.



The one sample question still unanswered is a definition thing. So maybe
the root question should be, why is one definition better than another?

I learned the definition of microprocessor to be a single-chip CPU, and
a microcomputer to be a computer based on a microprocessor. But I never
questioned it. Why is that a useful definition?

Maybe it is a measure of how hard it would be to build a system around
it. Which in turn could be correlated with cost, and so with popularity.
By that reasoning, if you get the same functionality out of a smallish
chip-set as a single chip, and the price is the same, both should be
considered as micros.

Or maybe it has more to do with physical size of the end result; if you
have a single chip instead of four, it leaves you with more room to put
the rest of the computer on that same PC board. Maybe that could be
really important for hobbyists. (I know my own attempts at homebrewing
were all SBC's.)

But there is a red herring in all this. External VLSI support chips
are a convenience. You could have built an 8080 system without the 8228.
You would just use a boatload of TTL instead. So again, the issue is
probably just cost of doing so (money, time, space). Was the 8080 more
expensive in any way because of the 8228's existance? No. Was it any
less of a microcomputer? Either the 8228 was enough of an improvement
over the boatload of TTL that it made 8080 systems doable (ie, made it a
micro), or maybe the lack of the 8228 circuitry in the 8080 chip itself
still made it impractical for some (ie, made it a non-micro). It depends
on where your thresholds are. You can still argue about whether or not
the 8080 without an 8228 is a complete CPU, but my point is that this may
not be worth arguing. What is the practical impact of having the entire
CPU on one chip vs. two? How does it change anyone's behaviour? *That*
could be worth some discussion.

I have my own ideas about which things are micros and which are not, but
in retrospect, the definition that I was taught is not a useful one; it
does not classify things into categories that I can use to any benefit.

        Cheers,
        Bill.
Received on Wed Oct 07 1998 - 16:55:02 BST