12 May
2015
12 May
'15
7:30 p.m.
Date: Mon, 11 May 2015 10:17:41 -0700
From: "Kirk B Davis" <kirkbdavis at hush.com>
Subject: Re: PDP-12 Restoration at the RICM
Pictures?? :-)
http://www.ricomputermuseum.org/Home/equipment/dec-pdp-12
--
Michael Thompson
13 May
13 May
9:37 p.m.
From the web page:
"so it actually has
two processors"
Is that true? I haven't had time to make a detailed study of the
PDP-12 logic design, but my understanding was that unlike the LINC-8,
which basically was two separate processors mashed together, the
PDP-12 was a single integrated processor with two modes (PDP-8 and
LINC). I was told that there were some commonalities that were taken
advantage of, such that merging it resulted in reduction of the total
logic necessary as compared to the LINC-8.
14 May
14 May
11:28 a.m.
On Wed, 13 May 2015 19:37:57 -0600
Eric Smith <spacewar at gmail.com> wrote:
I owned a PDP-12 for years. I bought it directly from DEC shortly after
it went out of production for $3,000!
My PDP-12 had 12Kw of RAM, an RF08 (2x256K) disk, dual TU56 Linctapes,
TC08 and TU55, ASR-33 and ADM-3 terminals, 9-track reel to reel mag
tape. In addition, because I wanted really high speed paper tape, I
created an interface to a Tally 1000cps PT reader and high speed punch.
I was the last official DECUS Coordinator for the PDP-12, so my PDP-12
was used to copy the contents of the DECUS PDP-8 and PDP-12 libraries to
all of the different media using my PDP-12. I still have some of the
"DECUS dollars" that were used to make refunds to users. They could
subsequently use those "DECUS dollars" to purchase future copies. (DECUS
had standard copy charges for different types of media).
I donated my PDP-12 with all it's peripherals and the complete PDP-8 and
PDP-12 DECUS libraries to the Computer History Museum around 1996.
That library also contains the only known master copy of the DIAL OS
source code. DIAL was an OS that ran in LINC mode on the PDP-12.
Shortly after DEC shutdown production of the PDP-12, they offered me
the master source, since they were not planning to continue support of
DIAL.
Regarding the question about number of "processors" in the PDP-12:
The PDP-12 does NOT have two processors. As Eric suggested, it was a
single integrated processor with two instruction sets - PDP-8 and LINC.
Much of the logic was shared between the two.
When in PDP-8 mode, a single instruction would put the 12 into LINC mode
and vice versa.
Cheers,
Lyle
--
Bickley Consulting West Inc.
http://bickleywest.com
"Black holes are where God is dividing by zero"
From the web
page:
"so it actually has two processors"
Is that true? I haven't had time to make a detailed study of the
PDP-12 logic design, but my understanding was that unlike the LINC-8,
which basically was two separate processors mashed together, the
PDP-12 was a single integrated processor with two modes (PDP-8 and
LINC). I was told that there were some commonalities that were taken
advantage of, such that merging it resulted in reduction of the total
logic necessary as compared to the LINC-8. 
9:26 p.m.
On 05/14/2015 10:28 AM, Lyle Bickley wrote:
On Wed, 13 May 2015 19:37:57 -0600
Eric Smith <spacewar at gmail.com> wrote:
I owned a PDP-12 for years. I bought it
directly from DEC shortly after
it went out of production for $3,000!
My PDP-12 had 12Kw of RAM, an RF08 (2x256K) disk, dual TU56 Linctapes,
TC08 and TU55, ASR-33 and ADM-3 terminals, 9-track reel to reel mag
tape. In addition, because I wanted really high speed paper tape, I
created an interface to a Tally 1000cps PT reader and high speed punch.
I was the last official DECUS Coordinator for the PDP-12, so my PDP-12
was used to copy the contents of the DECUS PDP-8 and PDP-12 libraries to
all of the different media using my PDP-12.
Ahh, that explains all the drives!
I was the local DECUS librarian in the St. Louis area,
mostly for VAX stuff. I got some CDC Keystone 9-track
1600/6250 tape drives at a surplus shop, and did the tape
copying in my home basement.
I wrote a program that could read a tape and put it in a
container file format on disk, and then spool off copies to
tape at full streaming speed.
Jon
From the
web page:
"so it actually has two processors"
Is that true? I haven't had time to make a detailed study of the
PDP-12 logic design, but my understanding was that unlike the LINC-8,
which basically was two separate processors mashed together, the
PDP-12 was a single integrated processor with two modes (PDP-8 and
LINC). I was told that there were some commonalities that were taken
advantage of, such that merging it resulted in reduction of the total
logic necessary as compared to the LINC-8. 
16 May
16 May
9:19 a.m.
New subject: 8/12 DECUS library, was PDP-12 Restoration at the RICM
On Thu, May 14, 2015 at 08:28:03AM -0700, Lyle Bickley wrote:
I donated my PDP-12 with all it's peripherals and the complete PDP-8 and
PDP-12 DECUS libraries to the Computer History Museum around 1996.
All the rumors I had heard said they were lost. This is good to hear.
Was this both the writeups and the programs?
If I read the history right 1996 was when what is now called the CHM in
California was started. Is that where it was donated?
I assume then that it still exists and hopefully will make it online
at some time. Do you have any knowledge of its current status?
11:56 a.m.
New subject: 8/12 DECUS library, was PDP-12 Restoration at the RICM
On 5/16/15 6:19 AM, David Gesswein wrote:
I assume then that it still exists and hopefully will
make it online
at some time. Do you have any knowledge of its current status?
It is in the queue to be read. CHM just purchased a third building located
in Fremont that my office and lab will be moving to, along with the software
and document collections.
I'm hoping to have the media recovery lab up and running again
in the fall. I am totally consumed right now with getting ready for the move.
14 May
14 May
11:46 a.m.
On 05/13/2015 08:37 PM, Eric Smith wrote:
I'm pretty sure this is true, the amount of logic in the
machine is not that much more than similar 12-bit CPUs.
The ALU had to handle both ones-complement and two's
complement operations, and the instruction decode logic
needed to be about double, but the data paths logic could
all be done with one implementation.
I did use the PDP-12 at Washington University, and it was a
real nice machine!
Jon
From the web
page:
"so it actually has two processors"
Is that true? I haven't had time to make a detailed study of the
PDP-12 logic design, but my understanding was that unlike the LINC-8,
which basically was two separate processors mashed together, the
PDP-12 was a single integrated processor with two modes (PDP-8 and
LINC). I was told that there were some commonalities that were taken
advantage of, such that merging it resulted in reduction of the total
logic necessary as compared to the LINC-8.
3356
days inactive
3360
days old
6 comments
6 participants
participants (6)
-
aek＠bitsavers.org -
djg＠pdp8online.com -
elson＠pico-systems.com -
lbickley＠bickleywest.com -
michael.99.thompson＠gmail.com -
spacewar＠gmail.com