21 Apr
1997
21 Apr
'97
5:23 p.m.
Date: Sun, 20 Apr 1997 07:21:01 -0400 (EDT)
From: Doug Spence <ds_spenc(a)alcor.concordia.ca>
To: classiccmp(a)u.washington.edu
Subject: PET stuff
Does anyone out there know much about the old PET 2001
machines?
I know pretty much PET software & usage, and have a bunch of good books
to help me on other aspects... ;)
I received a PET a couple of years ago, in which all
of the 6550 SRAMs
were fried. I replaced them with the chips from another PET 2001 (one
with the miniature keyboard, from 1977) and the system worked fine.
Does anyone know how all of the memory chips could've been killed?
I tried them in various patterns in the sockets, and it does seem as if
all 16 of them are fried.
Never heard of that, but I did have a friend who tried expanding PET
memory by piggybacking RAM chips ; that fried his... (beware, he's
still out there...)
Anyway, is it still possible to get 6550s anywhere?
And if not, is there
a replacement that could be used?
MOS technologies found out they wern't good RAM manufacturers, the
comptible and available chip number you seek is 2114. Which I have
found in a Jameco Catalog (415-592-8097)
Even better: Can I simply replace the 6550s with
another type of chip and
get more RAM in the system? Most of my software works in 8K, but I do
have some music files that require more. (I have one of those external
music boards that plugs into the cassette2 and user ports, that delivers
four voices.)
Wow! An MTU sound board! Got to hear a demonstration of it some 15
years ago, pretty nice sound! One of these days I might come across one
of 'em for my own.
Back to RAM, from the next paragraph I would say that you can add via
that expansion
board. But just in case I'm mistaken, here is something I found in
Nick Hampshire's
PET Revealed:
... The old 8K machines used 4K bit static RAMs, these were one of two
types the 6550 and the 2114. Both these chips are functionally
indentical in most respects since they are organised as 1K by 4 bits.
The latest versions of the static RAM 8K machines used the 6550....
... The new 32K and 16K dynamic RAM machines use the 4116 memory chip
and the dynamic 8K the 4108. These two RAM chips are pin compatable,
with the 4116 having 16K bits of memory and the 4108 8K bits. This is
useful since it allows the same circuit board to be used for all sizes
of machine. Memory on the 16 and 32K machines is organised as two banks
each of 16K bytes, only one bank being implemented in the 16K....
Now, another question. With that same PET, came an
expansion board of
some kind. Its like a daughterboard, physically mounted on posts above
the motherboard, but connected via the memory expansion connector on the
side.
It appears (yes) to be a memory board, with 16 RAM chips on it. At least,
they look like they could be RAM chips, judging by the traces on the
board. However, I've never seen RAM chips with gold contacts and gold
plates on their backs before, as six of these chips have, so I'm wondering
if this could be more than just a memory board.
Sounds like an Expandamem or ExpandaPET to me, I have the docs for it, I
think it has schematics and stuff. Mine have the same chips too, look
like tiny ROMs or EPROMs..
The board is dead, BTW. The PET won't operate
with the board plugged in.
It just comes up with a screenful of garbage characters.
[clip]
Both connectors on the cable that leads from the
expansion board to the
motherboard are noticeably burnt. In both cases, the burn marks surround
the pin that connects to the black wire.
OUCH!!!! That's gotta hurt... Hope you figure out what did that.
The only identifying mark on the board is the text:
R 3014
rev.
C
COPYRIGHT 1978 R.C.Factor
My ExpandaPET book has (c) 1979 Computhink (yours could be an earlier
version?), also my board has four breadboard (edgecard) sockets to add
devices like disk drive controller cards and the like.
Does anyone have any better guesses than me as to its
function? (Can the
edge connector on the side of the PET be used for anything other than RAM
expansion?)
The only other thing I could think of it being (if it had a patch into
the monitor connector) would be a Visible Memory (hi-res graphics)
board. But I doubt that.
Let me know If you want a copy of the documentation I have for my board
to see if it will help.
Doug Spence
ds_spenc(a)alcor.concordia.ca
------------------------------
What I bought: Atari 1200 XL, 1050 Disk Drive, and Supra Atari 300 baud
modem (all sans power supplies *sigh*) for $15 at a flea market (need
power supplies to test them still), and a (working!) Apple ImageWriter
II for $14.95 at a thrift shop. Software.
What I passed up:
2 CoCo 3s (bare), one for $15 one unknown
1 CoCo dual 5.25" Disk Drive price unknown
1 black/silver TI 99/4a (bare) $10
1 Atari 800 (bare, but had BASIC cart inside) $10
Plus/4, C-64, an MPS 801, tons of IBM clones didn't bother pricing.
Oh! Last week I happend upon a Panasonic MSX unit! Looked
interesting, unfortunately the guy couldn't sell it cause 'they haven't
decided how much to price it' (hence it would probably be expensive),
sure looked neat, had alot of I/O and noted a switch to change tape baud
rates. (they had the tape program/books already out on the floor just
waiting for kids to tear them apart.)
Larry Anderson
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Visit our web page at: http://www.goldrush.com/~foxnhare
Call our BBS (Silicon Realms BBS 300-2400 baud) at: (209) 754-1363
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
On Thu, 17 Apr 1997, Sam Ismail wrote:
> Hey, let's have a contest. Let's see who can score the best lot of
> classic computers this weekend. We can score each other based on the
> type and age of the computers/software/accessories we got, then tally up
> the points and whoever has the highest score gets a pat on the back.
24 Apr
24 Apr
2:38 a.m.
On Mon, 21 Apr 1997, Larry Anderson & Diane Hare wrote:
OK, cool. I'm actually need some 2114s for repairs to a VIC-20 3K
Expander cartridge, too, so I can just buy more of them when I actually
get myself to a place that sells them.
BTW: Who here thinks I'm crazy for wanting to run an "old-time BBS" off a
VIC-20? Who here thinks it's impossible? :)
I doubt I will. Presumably it was caused by some kind of accident, not
through some fault in the PET, because the PET the board came in has been
running for a couple of years (with the other PET's RAM in it) and hasn't
experienced any problems. The memory board, though, is of course quite
suspect. Perhaps I should replace those capacitors and regulators before
I replace the RAM and try to fire it up again? (How would one test a
capacitor to see if it's OK?)
There aren't any extra connectors on my board. The only connectors are
for power in, power out, and the one that plugs into the side expansion
connector.
I know pretty much PET software & usage, and have
a bunch of good books
to help me on other aspects... ;)
There used to be a copy of Osborne's "PET/CBM Personal Computer Guide"
around here someplace, but I suspect my brother took it with him when he
moved out, even though he's a C64 man. (Darn!) I really need to find a
good shop with old computer books in it. All of the second-hand
bookstores I've been to specifically state that they don't keep computer
books or magazines older than 5 years (or so) old. :/
Never heard of that, but I did have a friend who tried
expanding PET
memory by piggybacking RAM chips ; that fried his... (beware, he's
still out there...)
Interesting. I performed the piggyback RAM hack on my Amiga 1000 (back
when it was worth real money) and that seems to still be holding up. I
*don't* want to do that to my PET, though. :) (In fact, in retrospect, I
wish I hadn't done it to my Amiga, either - I should've bought an Insider
board instead and keept the Amiga in its original condition. I wasn't a
collector yet, though. :) )
Anyway, is it
still possible to get 6550s anywhere? And if not, is there
a replacement that could be used?
MOS technologies found out they wern't good RAM manufacturers, the
comptible and available chip number you seek is 2114. Which I have
found in a Jameco Catalog (415-592-8097) Wow! An MTU sound board! Got to hear a demonstration
of it some 15
years ago, pretty nice sound! One of these days I might come across one
of 'em for my own.
The local high school had three PETs with these sound boards, and this is
one of them. (Curiously, at the time, the "Computer Science" department of
the same high school only had a single TRS-80 Model I and an Altair 8800.)
The music teacher wrote software to teach scales and chords, in BASIC,
based on the Cursor #4 tape's cover program. I found copies of these
things in my brother's cassette collection (I was still in elementary
school at the time the PETs were in use).
The sound generated by the board *is* nice. I had an online friend over
during the holidays, who collects old synthesizers, and he was quite
impressed with the thing. Too bad I couldn't find the cassette with the
professional music software on it (I forget what it's called) that lets
you compose the music on the staff on the screen, and that scrolls the
music as it plays. It's really impressive for an 8K machine!
Back to RAM, from the next paragraph I would say that
you can add via
that expansion
board. But just in case I'm mistaken, here is something I found in
Nick Hampshire's
PET Revealed:
... The old 8K machines used 4K bit static RAMs, these were one of two
types the 6550 and the 2114. Both these chips are functionally
indentical in most respects since they are organised as 1K by 4 bits.
The latest versions of the static RAM 8K machines used the 6550....
Interesting that he says the latest versions of the 8K machines use the
6550... It's possible the old 8K here with the miniature multicoloured
keyboard (love that thing!) had its RAM replaced at some point. It was,
after all, an abused school machine, and the lid wasn't screwed down. (The
sockets in that particular machine are so bad there's no point in screwing
the lid down! Having to re-seat chips is a regular occurrence.)
... The new 32K and 16K dynamic RAM machines use the
4116 memory chip
and the dynamic 8K the 4108. These two RAM chips are pin compatable,
with the 4116 having 16K bits of memory and the 4108 8K bits. This is
useful since it allows the same circuit board to be used for all sizes
of machine. Memory on the 16 and 32K machines is organised as two banks
each of 16K bytes, only one bank being implemented in the 16K....
So I guess Commodore stopped drilling holes in motherboards to prevent
upgrade? :)
I was hoping these numbers would match something on that expansion board,
but they don't. :/
The majority of the non-MOSTEK chips that appear to be memory chips, are
marked with MM5298J-4A, one is MM5290J-3, another is MM5290N-3... oops! I
take the last paragraph back! One of the non-gold-plated MOSTEK chips is
a 4116! We have identification! :)
Assuming all these chips are the same, this was a 16K RAM board. This'd
be nice to get running.
Sounds like an Expandamem or ExpandaPET to me, I have
the docs for it, I
think it has schematics and stuff. Mine have the same chips too, look
like tiny ROMs or EPROMs..
Yeah, those chips are bizarre.
The board is
dead, BTW. The PET won't operate with the board plugged in.
It just comes up with a screenful of garbage characters.
[clip]
Both connectors on the cable that leads from the
expansion board to the
motherboard are noticeably burnt. In both cases, the burn marks surround
the pin that connects to the black wire.
OUCH!!!! That's gotta hurt... Hope you figure out what did that. The only
identifying mark on the board is the text:
R 3014
rev.
C
COPYRIGHT 1978 R.C.Factor
My ExpandaPET book has (c) 1979 Computhink (yours could be an earlier
version?), also my board has four breadboard (edgecard) sockets to add
devices like disk drive controller cards and the like. The only other thing I could think of it being (if it
had a patch into
the monitor connector) would be a Visible Memory (hi-res graphics)
board. But I doubt that.
Oooh... I wish. :) I didn't think you could even get such a thing for a
2001, I thought graphics boards were the domain of the 8032 and like
systems. No idea why I'd think there'd be such limitations on one PET and
not on another, though. :)
Let me know If you want a copy of the documentation I
have for my board
to see if it will help.
I'll pass on that (for now, anyway) as it seems to be a simple RAM board.
If I replace all the parts, it should work, and presumable there's nothing
I'd really have to know about to use it. :)
BTW, there's also another piece of bizarre PET expansion around the house
somewhere... Another 16K of expansion, actually. That's what those large
music files were created with. But the thing is HUGE and it consists of
exposed circuit boards, so I didn't particularly want to use it in its
current state.
This memory expansion has its own power supply. The cable from the
expansion connector on the side of the PET goes to the top edge of a large
board that is in turn plugged into a socket on a long expansion bus type
of thing (with the Vector Graphics label on it). There is another board
of equal size to the first also plugged into this expansion bus, right
beside it. There are only the two sockets on the long PCB of the
expansion bus, but it'd be easy to add more sockets. I should dig this
thing out to see if there's anything else interesting to say about it.
Seems like an awful lot of space for 16K. My little internal board would
be much nicer.
This strange contraption wouldn't be some kind of interface between the
PET and an S100 bus, would it? (THAT would be cool!) How would I know an
S100 bus if I saw one? :)
Larry Anderson
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Visit our web page at: http://www.goldrush.com/~foxnhare
Call our BBS (Silicon Realms BBS 300-2400 baud) at: (209) 754-1363
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Doug Spence
ds_spenc(a)alcor.concordia.ca
7:04 a.m.
New subject: Old Computer Books (was Re: Pets & Silly Game)
There used to be a copy of Osborne's "PET/CBM
Personal Computer Guide"
around here someplace, but I suspect my brother took it with him when he
moved out, even though he's a C64 man. (Darn!) I really need to find a
good shop with old computer books in it. All of the second-hand
bookstores I've been to specifically state that they don't keep computer
books or magazines older than 5 years (or so) old. :/
I've found that one of the best sources for old computer books and
magazines is often overlooked... the LIBRARY. Most public libraries have
a nice collection of books on old personal computers from the 1st wave of
PC popularity (early 80s). I know that my hometown (Austin, TX) has a
huge collection of books with titles like "6502 Assembly Projects" and
"1001 things to do with your PET". Plus, most libraries archive
magazines. My university has a full set of many computer magazines that
have been around since the 70s such as Byte.
However, if you're looking to own the books or magazines, this doesn't
help. But if you're just looking for info or wanting to get some kicks
by reading old stuff, your local public or university library is a great
place to start.
8:43 a.m.
New subject: Old Computer Books (was Re: Pets & Silly Game)
At 11:04 AM 4/24/97 -0500, Starling wrote:
I've found that one of the best sources for old
computer books and
magazines is often overlooked... the LIBRARY... However, if you're
looking to own the books or magazines, this doesn't help.
actually my experience has been the Library *is* a good place to find old
computer books to *own*. our local libraries routinely sell off older
books that they don't feel are pertinent any more. they cost 50 cents
(paperback) or $1 (hardback)... so stop in at your local library's book
sale booth and you might pick up a classic or two.
- gfr
+=========================================================+
| Glenn F. Roberts, Falls Church, VA
| Comments are my own and not the opinion of my employer
| groberts(a)mitre.org
9:08 a.m.
New subject: Old Computer Books (was Re: Pets & Silly Game)
I would say that the library is the best place to find these things.
I found a Vic-20 Programmers Reference Guide in my local one. They
even let me have it for $5!
Les
7:54 p.m.
New subject: Old Computer Books (was Re: Pets & Silly Game)
I've found that one of the best sources for old
computer books and
magazines is often overlooked... the LIBRARY. Most public libraries have
a nice collection of books on old personal computers from the 1st wave of
PC popularity (early 80s).
[...]
However, if you're looking to own the books or
magazines, this doesn't
help. But if you're just looking for info or wanting to get some kicks
by reading old stuff, your local public or university library is a great
place to start.
Of course, many libraries do hold "book sales" in order to dispose of
"obsolete" materials . . .I've snagged several old computer books from
public library book sales.
28 Apr
28 Apr
12:51 a.m.
New subject: Old Computer Books (was Re: Pets & Silly Game)
On Thu, 24 Apr 1997, Starling wrote:
I've found that one of the best sources for old
computer books and
magazines is often overlooked... the LIBRARY. Most public libraries have
a nice collection of books on old personal computers from the 1st wave of
PC popularity (early 80s).
Actually, I've become fairly well acquainted with the old computer book
collection of the university library here. They do have some great books,
including a couple on the KIM-1. It was from library books that I learned
how to use CP/M. But the only PET books this library has are things like
collections of type-in programs for the PET, and books on using the PET in
an educational environment. Nothing good and technical.
Possibly the coolest thing apart from the book on KIM-1 interfacing
projects, though, is the book the library has on the Memotech MTX512's
BASIC. I borrowed that one and ended up typing up a small manual into an
AmigaGuide document in case I ever should run across such a beast.
I know that my hometown (Austin, TX) has a
huge collection of books with titles like "6502 Assembly Projects" and
"1001 things to do with your PET". Plus, most libraries archive
magazines. My university has a full set of many computer magazines that
have been around since the 70s such as Byte.
My university's library had a whole floor dedicated to periodicals, but
that library was closed and I haven't seen a sign of that material since
the new library opened. I suppose I should ask someone if they kept the
stuff.
However, if you're looking to own the books or
magazines, this doesn't
help. But if you're just looking for info or wanting to get some kicks
by reading old stuff, your local public or university library is a great
place to start.
I find that most of the computer-related books in this library are too
theoretical. There really isn't that much that is linked to one piece of
hardware.
I did find a few good books in a Salvation Army store on Thursday, though.
I was hoping for some hardware (they had NONE), but I'm quite pleased with
some of the books I found. Nothing involving the PET, though. :)
Doug Spence
ds_spenc(a)alcor.concordia.ca
24 Apr
24 Apr
9:54 p.m.
On Thu, 24 Apr 1997, Doug Spence wrote:
Interesting. I performed the piggyback RAM hack on my
Amiga 1000 (back
when it was worth real money) and that seems to still be holding up. I
*don't* want to do that to my PET, though. :) (In fact, in retrospect, I
wish I hadn't done it to my Amiga, either - I should've bought an Insider
board instead and keept the Amiga in its original condition. I wasn't a
collector yet, though. :) )
Don't worry. It just adds character to the machine. You can just say
some "unknown" hacker made the mod if anyone asks. And don't forget to
mention it adds character to the machine.
BTW: Who here thinks I'm crazy for wanting to run
an "old-time BBS" off a
VIC-20? Who here thinks it's impossible? :)
Not me. Of course its totally possible. As soon as there are 27 hours
in the day I'm going to be putting up and old style BBS on my Sinclair
ZX80! (Just kidding, it'll be on a Linux box probably, but I'll just say
it runs on a Sinclair).
This strange contraption wouldn't be some kind of
interface between the
PET and an S100 bus, would it? (THAT would be cool!) How would I know an
S100 bus if I saw one? :)
It would have slots that have 100 pin connectors (50 on side side, 50 on
the other).
Sam
-------------------------------------------------------------------------------
Computer Historian, Programmer, Musician, Philosopher, Athlete, Writer, Jackass
28 Apr
28 Apr
2:57 a.m.
On Thu, 24 Apr 1997, Sam Ismail wrote:
Now, I think I'll declare a ZX80-run BBS as an impossibility, if only
because I really want to see it done and I know that whenever anything is
declared "impossible" it just acts as added incentive to hackers. ;)
Actually, I just picked up an excellent book entitled "The Micro-Computer
Builder's Bible" by Chris Johnston, and it's got some pictures of S100
boards in it (I like the one labeled "A typical 4K static board"). It
looks like the chances are excellent that what I've got is an S100 bus
interface for the PET, but I really have to drag the thing out of storage
to count the pins on it to make sure.
If it IS an S100 bus interface, I wonder where I could find documentation
on how to use the thing. It would be extra neat if I could plug I/O
boards and graphics cards into the PET this way. :)
On Thu, 24 Apr 1997, Doug Spence wrote:
Nah, I may as well claim the credit. I think it says more for my bravery
than my skill, though, because I did a really messy job and it's some sort
of minor miracle that it worked. (I was too imatient to get it done and
didn't wait to collect the right tools first... ended up having to REBUILD
pins on chips on the motherboard that had been sheared off to
barely-visible protrusions of metal, using model railroad connectors.)
Interesting. I performed the piggyback RAM hack
on my Amiga 1000 (back
when it was worth real money) and that seems to still be holding up. I
*don't* want to do that to my PET, though. :) (In fact, in retrospect, I
wish I hadn't done it to my Amiga, either - I should've bought an Insider
board instead and keept the Amiga in its original condition. I wasn't a
collector yet, though. :) )
Don't worry. It just adds character to the machine. You can just say
some "unknown" hacker made the mod if anyone asks. And don't forget to
mention it adds character to the machine. BTW: Who here
thinks I'm crazy for wanting to run an "old-time BBS" off a
VIC-20? Who here thinks it's impossible? :)
Not me. Of course its totally possible. As soon as there are 27 hours
in the day I'm going to be putting up and old style BBS on my Sinclair
ZX80! (Just kidding, it'll be on a Linux box probably, but I'll just say
it runs on a Sinclair). This strange
contraption wouldn't be some kind of interface between the
PET and an S100 bus, would it? (THAT would be cool!) How would I know an
S100 bus if I saw one? :)
It would have slots that have 100 pin connectors (50 on side side, 50 on
the other). Sam
-------------------------------------------------------------------------------
Computer Historian, Programmer, Musician, Philosopher, Athlete, Writer, Jackass
Doug Spence
ds_spenc(a)alcor.concordia.ca
9947
days inactive
9954
days old
8 comments
7 participants
participants (7)
-
dastar＠crl.com -
ds_spenc＠alcor.concordia.ca -
foxnhare＠goldrush.com -
groberts＠mitre.org -
more＠camlaw.rutgers.edu -
starling＠umr.edu -
transit＠primenet.com