20 May
2008
20 May
'08
10:53 a.m.
----------Original Message:
Date: Tue, 20 May 2008 10:28:11 -0600
From: Richard <legalize at xmission.com>
Subject: Re: Capacitor values for original PET power supply?
In article <20080520111556.GD1028 at usap.gov>,
Ethan Dicks <ethan.dicks at usap.gov> writes:
The memory board looks interesting - any idea what was
meant to go
in the cartridge slots?
I wonder if it isn't a memory board scavenged out of some other piece
of hardware and simply hacked to appear as more memory in the PET?
--
----------Reply:
I think if that were the case, the interface to the PET expansion connector
would be a lot messier than what looks like a straight-across ribbon cable
with just a transition board to connect to the old-style edge connector, so
it does look like it's specifically for the PET, presumably with optional
different transition boards for the different PET connectors.
An interesting board indeed; what could those slots be for? I don't think
C64 carts would work very well in a PET...
m
20 May
20 May
11:27 a.m.
M H Stein wrote:
----------Original Message:
Date: Tue, 20 May 2008 10:28:11 -0600
From: Richard <legalize at xmission.com>
Subject: Re: Capacitor values for original PET power supply?
In article <20080520111556.GD1028 at usap.gov>,
Ethan Dicks <ethan.dicks at usap.gov> writes:
It's labeled as a "Compu/Think Expandamem" which is listed as a
" RAM
Expansion w/KIM bus for original PET" at
http://www.portcommodore.com/petperiph.php. I'm going to be holding
onto that, probably hook it back up after I get the basic system working
again.
I've dumped the ROMS on the handbuilt expansion board. If you're
interested in taking a look, see
http://yahozna.dyndns.org/computers/pet. I've named them as the labels
on the EPROMS indicate. I've glanced through them, there are no ASCII
strings or anything to make them easy to identify. Haven't done a
disassembly yet...
Josh
The memory board looks interesting - any idea
what was meant to go
in the cartridge slots?
I wonder if it isn't a memory board scavenged out of some other piece
of hardware and simply hacked to appear as more memory in the PET?
21 May
21 May
5:42 a.m.
On Tue, May 20, 2008 at 11:27:17AM -0700, Josh Dersch wrote:
I've dumped the ROMS on the handbuilt expansion
board. If you're
interested in taking a look, see
http://yahozna.dyndns.org/computers/pet. I've named them as the labels
on the EPROMS indicate. I've glanced through them, there are no ASCII
strings or anything to make them easy to identify. Haven't done a
disassembly yet...
I did a quick disassembly. I got pretty random stuff from A000.HEX,
but the other two had reasonable contents.
DOS.HEX is almost certainly some version of the "DOS Wedge".
MCM-9000.HEX has reasonable code, but I only found contents
up to 2K, but the code references constants up to 4K... either
my S-record tool lost half the data, or, given the hex file
size, half is missing.
It ends like this...
.$97e6 20 4c 98 jsr $984c
.$97e9 85 fd sta $fd
.$97eb 86 fe stx $fe
.$97ed 20 5d 98 jsr $985d
.$97f0 8d 92 02 sta $0292
.$97f3 8e 93 02 stx $0293
.$97f6 20 a4 98 jsr $98a4
.$97f9 20 60 98 jsr $9860
.$97fc 85 fb sta $fb
.$97fe 86 fc stx $fc
Between subroutines past $9800, and some tables referenced
earlier, and a complete lack of a reasonable end of the code,
I'd say that's only the half of it.
It was common to stuff code in 2K or 4K chunks between $9000
and $BFFF... the hex files, though, seem to only describe
2K chunks. Are your ROMs all 2K and some haven't been copied
yet?
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 21-May-2008 at 12:30 Z
South Pole Station
PSC 468 Box 400 Temp -77.3 F (-60.7 C) Windchill -114.4 F (-81.4 C)
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
10:41 a.m.
I did a quick disassembly. I got pretty random stuff
from A000.HEX,
but the other two had reasonable contents.
DOS.HEX is almost certainly some version of the "DOS Wedge".
MCM-9000.HEX has reasonable code, but I only found contents
up to 2K, but the code references constants up to 4K... either
my S-record tool lost half the data, or, given the hex file
size, half is missing.
It ends like this...
.$97e6 20 4c 98 jsr $984c
.$97e9 85 fd sta $fd
.$97eb 86 fe stx $fe
.$97ed 20 5d 98 jsr $985d
.$97f0 8d 92 02 sta $0292
.$97f3 8e 93 02 stx $0293
.$97f6 20 a4 98 jsr $98a4
.$97f9 20 60 98 jsr $9860
.$97fc 85 fb sta $fb
.$97fe 86 fc stx $fc
Between subroutines past $9800, and some tables referenced
earlier, and a complete lack of a reasonable end of the code,
I'd say that's only the half of it.
It was common to stuff code in 2K or 4K chunks between $9000
and $BFFF... the hex files, though, seem to only describe
2K chunks. Are your ROMs all 2K and some haven't been copied
yet?
-ethan
That's all of them unfortunately, they're all 2716s. There's 8
sockets
on the board, but only three were populated when I got the machine. So
I guess we may never know what manner of super-awesome stuff was on
these things :).
Thanks,
Josh
22 May
22 May
12:02 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org on behalf of Josh Dersch
Sent: Thu 22-May-08 05:41
To: On-Topic Posts Only
Subject: Re: Capacitor values for original PET power supply?
I wrote:
> I did a quick disassembly. I got pretty random stuff from A000.HEX,
> but the other two had reasonable contents.
>
> DOS.HEX is almost certainly some version of the "DOS Wedge".
>
> MCM-9000.HEX has reasonable code, but I only found contents
> up to 2K...
Josh writes:
That's all of them unfortunately, they're all
2716s. There's 8 sockets
on the board, but only three were populated when I got the machine. So
I guess we may never know what manner of super-awesome stuff was on
these things :).
That's unfortunate. I think the DOS Wedge is less than the 2K anyway, and
the source for it is floating around somewhere (on ther CBM MACRO Assembler
disk?), so it wouldn't be hard to reconstruct in any case.
I really can't tell what's at $A000, but perhaps an analysis of the code
from $9000 might reveal what it was part of.
Back in the day, there were a number of BASIC extension ROMs, extended
ML Monitor ROMs, tape accelerators (like The Rabbit), and wordprocessing
subroutines/key dongle ROMs. Not an exhaustive list, but it's certainly
a place to start when trying to guess what the ROM was doing.
-ethan
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