10 May
2012
10 May
'12
5:24 p.m.
Here's a puzzler.
One of the two memory boards from my PDP-11/35 is short four ICs. See:
http://www.loomcom.com/projects/pdp11-35/ms11_j.jpg
It looks like it was an 8KW board that was user-expanded to 16KW, and if
I'm reading the switches correctly it was configured for starting
address 000000. (The other 16KW board I have is configured to start at
address 100000)
Those four missing ICs seem weird, though. The other board is is fully
populated. Were they just pulled before the PDP was trashed? Or is that
a valid configuration?
-Seth
10 May
10 May
5:38 p.m.
On May 10, 2012, at 8:24 PM, Seth Morabito wrote:
Here's a puzzler.
One of the two memory boards from my PDP-11/35 is short four ICs. See:
http://www.loomcom.com/projects/pdp11-35/ms11_j.jpg
It looks like it was an 8KW board that was user-expanded to 16KW, and if
I'm reading the switches correctly it was configured for starting
address 000000. (The other 16KW board I have is configured to start at
address 100000)
Those four missing ICs seem weird, though. The other board is is fully
populated. Were they just pulled before the PDP was trashed? Or is that
a valid configuration?
Looks like they didn't populate the ninth chips (used for parity).
Someone more knowledgeable about Unibus than I would have to guess what
difference that might make.
- Dave
5:48 p.m.
* On Thu, May 10, 2012 at 08:38:13PM -0400, David Riley <fraveydank at gmail.com>
wrote:
Looks like they didn't populate the ninth chips (used for parity).
Someone more knowledgeable about Unibus than I would have to guess what
difference that might make.
Aha! OK, that would make sense, since this system does not have an M7850
Parity Control module, and therefore cannot use the parity bits.
-Seth
11 May
11 May
11:56 a.m.
Those four missing ICs seem weird, though. The other
board is is fully
populated. Were they just pulled before the PDP was trashed? Or is that
a valid configuration?
I don;t think it's a 'correct; configuration, but it can work.
Those extra ICs are more RAM chips, used to store the parity bits for
each byte. If you don't have a partiy generator/checker board in the
machine, it';ll work fine without them,
-tony
2:03 p.m.
New subject: Commodore Plus/4 Oddity
I was going through my vintage machines collection and happened to notice something
strange with a commodore plus/4 I have.
On the right side, there was an additional RCA connector that I had never seen before
this.
Opening it up, it appears to only have a wire jumpered from one of its connections to pin
6 on the serial port.
I can't imagine why someone would do this. Any ideas?
Pictures are here.
http://imgur.com/a/CFUPs
Kevin
13 May
13 May
1:36 p.m.
New subject: Commodore Plus/4 Oddity
I'm not 100% sure of the pinout for the serial port, but I've seen tapping
off of ports to provide additional power to external devices. Like the
Cardco Card?+G parallel printer interface has a connector with a single
wire that plugs into the cassette port for extra power. I've seen people
instead run this to pin 7 of the game controller port of C64's, etc., to
keep the cassette port free. So, maybe its something similar.
Garrett Meiers
On Fri, May 11, 2012 at 4:03 PM, Kevin Reynolds <tpresence at hotmail.com>wrote:
I was going through my vintage machines collection and happened to notice
something strange with a commodore plus/4 I have.
On the right side, there was an additional RCA connector that I had never
seen before this.
Opening it up, it appears to only have a wire jumpered from one of its
connections to pin 6 on the serial port.
I can't imagine why someone would do this. Any ideas?
Pictures are here.
http://imgur.com/a/CFUPs
Kevin
3:35 p.m.
New subject: Commodore Plus/4 Oddity
On Fri, May 11, 2012 5:03 pm, Kevin Reynolds wrote:
I was going through my vintage machines collection and happened to notice
something strange with a commodore plus/4 I have.
On the right side, there was an additional RCA connector that I had never
seen before this.
Opening it up, it appears to only have a wire jumpered from one of its
connections to pin 6 on the serial port.
I can't imagine why someone would do this. Any ideas?
Pictures are here.
http://imgur.com/a/CFUPs
Kevin
That would create a nice easy external reset button... pin 6 of CBM IEC is
the reset signal.
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com
14 May
14 May
2:07 a.m.
New subject: Commodore Plus/4 Oddity
Pete,
We thought about that, but the plus/4 has an external reset button, in fact, it was about
an inch south of this connection. Now, perhaps a reset induced by another device would
make sense, but I can't figure out which device it could be, or why.
Kevin
Date: Sun, 13 May 2012 18:35:47 -0400
Subject: Re: Commodore Plus/4 Oddity
From: peter at rittwage.com
To: cctalk at classiccmp.org
CC: cctech at classiccmp.org
On Fri, May 11, 2012 5:03 pm, Kevin Reynolds wrote:
I was going through my vintage machines collection and happened to notice
something strange with a commodore plus/4 I have.
On the right side, there was an additional RCA connector that I had never
seen before this.
Opening it up, it appears to only have a wire jumpered from one of its
connections to pin 6 on the serial port.
I can't imagine why someone would do this. Any ideas?
Pictures are here.
http://imgur.com/a/CFUPs
Kevin
That would create a nice easy external reset button... pin 6 of CBM IEC is
the reset signal.
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com
4:59 a.m.
New subject: Commodore Plus/4 Oddity
On Mon, May 14, 2012 at 11:07 AM, Kevin Reynolds <tpresence at hotmail.com> wrote:
Pete,
We thought about that, but the plus/4 has an external reset button, ?in fact, it was
about an inch south of this connection. ?Now, perhaps a reset induced by another device
would make sense, but I can't figure out which device it could be, or why.
Kevin
Perhaps someone mistook the serial port for the AV port and wanted to
add a composite out jack?
--
Joachim Thiemann :: http://jthiem.bitbucket.org
5:05 a.m.
New subject: Commodore Plus/4 Oddity
On Mon, May 14, 2012 at 03:07:07AM -0600, Kevin Reynolds wrote:
Pete,
We thought about that, but the plus/4 has an external reset button, in
fact, it was about an inch south of this connection. Now, perhaps a
reset induced by another device would make sense, but I can't figure
out which device it could be, or why.
Some sort of watchdog? Hard to say without knowing what the computer was
used for.
/Pontus.
5:14 a.m.
New subject: Commodore Plus/4 Oddity
At least on the later C64, the IEC reset line is diode protected so that
this pin would only reset external devices (disk drives and printers) and
not the computer itself. I don't know if they Plus/4 is like this, but
it's likely.
-Pete
On Mon, May 14, 2012 5:07 am, Kevin Reynolds wrote:
Pete,
We thought about that, but the plus/4 has an external reset button, in
fact, it was about an inch south of this connection. Now, perhaps a reset
induced by another device would make sense, but I can't figure out which
device it could be, or why.
Kevin
Date: Sun, 13 May 2012 18:35:47 -0400
Subject: Re: Commodore Plus/4 Oddity
From: peter at rittwage.com
To: cctalk at classiccmp.org
CC: cctech at classiccmp.org
On Fri, May 11, 2012 5:03 pm, Kevin Reynolds wrote:
I was going through my vintage machines collection and happened to
notice
something strange with a commodore plus/4 I
have.
On the right side, there was an additional RCA connector that I had
never
seen before this.
Opening it up, it appears to only have a wire jumpered from one of its
connections to pin 6 on the serial port.
I can't imagine why someone would do this. Any ideas?
Pictures are here.
http://imgur.com/a/CFUPs
Kevin
That would create a nice easy external reset button... pin 6 of CBM IEC
is
the reset signal.
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com
8 Sep
8 Sep
3:51 p.m.
New subject: Teletype ASR33 Lot on Ebay
If people are still looking for Teletypes here's a nice lot of 3 with
reasonable shipping. In fact it is probably too low. In the US anyway.
Item # 200817228834
http://www.ebay.com/itm/ASR33-Teletype-Model-3320-3JA-LT-33-Lot-of-3-/20081…
5:17 p.m.
New subject: Teletype ASR33 Lot on Ebay
2012/9/9 mc68010 <mc68010 at gmail.com>:
If people are still looking for Teletypes here's a
nice lot of 3 with
reasonable shipping. In fact it is probably too low. In the US anyway.
Yeah. Bad for me and my money :-(
Item # 200817228834
http://www.ebay.com/itm/ASR33-Teletype-Model-3320-3JA-LT-33-Lot-of-3-/20081…
5:24 p.m.
New subject: Teletype ASR33 Lot on Ebay
On 9/8/2012 5:17 PM, SPC wrote:
2012/9/9 mc68010 <mc68010 at gmail.com>:
You got 'em then ? I'd say you got a great deal. Manuals, tape, and
all. That shipping seems really low too. Can't really ship a pallet of
anything anywhere except in town for $180.
If people are still looking for Teletypes
here's a nice lot of 3 with
reasonable shipping. In fact it is probably too low. In the US anyway.
Yeah. Bad
for me and my money :-(
9 Sep
9 Sep
7:09 a.m.
New subject: Teletype ASR33 Lot on Ebay
2012/9/9 mc68010 <mc68010 at gmail.com>:
On 9/8/2012 5:17 PM, SPC wrote:
You got 'em then ? I'd say you got a great deal. Manuals, tape, and all.
That shipping seems really low too. Can't really ship a pallet of anything
anywhere except in town for $180.
I live in Europe, in Spain being exact. I don't think it wouldn't be
expensive for all the shipment ways available.
Sergio
If people are still looking for Teletypes here's a nice lot of 3 with
reasonable shipping. In fact it is probably too low. In the US anyway.
Yeah. Bad for me and my money :-(
4256
days inactive
4377
days old
15 comments
11 participants
participants (11)
-
aek＠bitsavers.org -
ard＠p850ug1.demon.co.uk -
fraveydank＠gmail.com -
gm10＠consulnix.com -
joachim.thiemann＠gmail.com -
lists＠loomcom.com -
mc68010＠gmail.com -
peter＠rittwage.com -
pontus＠Update.UU.SE -
spedraja＠ono.com -
tpresence＠hotmail.com