From: Ethan Dicks (erd_at_infinet.com)
Date: 2002-07-11 20:46:21
> On Thu, Jul 11, 2002 at 11:35:24AM -0400, Ethan Dicks wrote:
> > If you _had_ a 32K PET, what does a B500 get you
> > that you didn't already have?
>
> Advanced features of the Commodore 600/700/B128/B256/B500/... include
>
> * a 6502 compatible CPU clocked with 2MHz
OK... Nice, but probably too little, too late.
> * an ACIA (6551) featuring baud rates up to 19200
Also nice (but available for a couple hundred bucks as a PET
add-in (I have one that fits in a ROM socket and taps R/W, etc
off of some jumper wires).
> * up to 960KB of adressable memory (up to 256KB on board)
Quite the little MMU in there, I would say. Who could afford
the memory back then anyway? Does it use 4116s or 4164s? Probably
4164s if they wanted to be able to close the lid - 32 chips vs
128 chips. I don't think the PSU could take that much draw.
> * a BASIC that can use up to 256KB memory
Nice. I remember running programs on a 32K PET that were banging
up against the ceiling. The problem is, of course, that with a
cassette tape, who *wants* to load/save programs that large. :-)
> * coprocessor capability (Z80 + 8086 boards were available or
> planned)
Nice for business (at the time), especially if the Z80 board came
with CP/M.
> And maybe some more. IMHO the greatest drawback was the use of a 8
> bit 6502 compatible CPU, which was no longer adaequate for a business
> machine at this time.
"At this time" being when? 1982? 1983? I knew plenty of businesses
still buying CP/M cards for the Apple II and still using CP/M on a
daily basis up through about 1985 (Kaypros mostly that late; other,
larger stuff in the 1982-1983 timeframe). 8-bits is not the issue;
8-bit *business* software probably is. Nobody was writing anything
new then. It was DOS and CP/M and a little Apple II and not much
else by 1984.
> Another problem was the missing software compatibility with the PETs.
Sure. Same problem killed the Apple III - not compatible enough
with the immensely popular Apple II.
> I've read an estimate that said, applications that make use of the
> new features need 30-40% of the code to get rewritten - which is way
> too much in my eyes.
25% is probably too much to be viable, especially given the development
techniques and disciplines of the day. Having been a professional
programmer as early as 1982 (assembly on a C-64, no less), companies
maintained entirely independent code bases for different platforms.
"Porting" was a huge hairy deal. I worked for a childrens' games
company in 1984 that supported the Apple II, the BBC Acorn and the
C-64. With the exception of a one-time migration (over custom-written
serial-transfer software) of code from the Apple II to the C-64, the
code, once split, never saw its ancestors again. Every feature and
every bug fix had to be done and done over, one platform at a time.
Things used to really suck in the 8-bit world.
> Similar thing for the P500: It can do anything that the C64 can do
> plus a lot more. But the C64 was already established and probably a
> lot cheaper.
The C-64 was $595 new, plus another $400-$600 for the 1541, c. 1982.
I'm sure the B500/P500 was quite a bit more than that. Besides, the
C-64 was clearly a home game machine. The B500/P500 at least *looked*
like a business machine. The C-64 was always perceived as a toy.
Thanks for the summary of what's "new and different" with the PET-II
line. I remember seeing them and being underwhelmed. I probably
looked at the price tag and was scared off. If I had that kind of
cash back then, I would have bought a 4040 drive (I had to wait five
more years to get them for $10 from the University surplus ;-)
I wouldn't leave one in the pile if I ran across one, but I don't
expect to be bidding on one on eBay anytime soon.
-ethan
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