25 Jan
2004
25 Jan
'04
12:47 p.m.
FYI - looks like a nice book. Tempted to bid on it myself, but I don't
have a PDP. Thought someone else might be interested.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3581863201&categ…
25 Jan
25 Jan
12:56 p.m.
Actually that (I am pretty sure) is a version that focuses mainly on the
PDP-8/a which was microprocessor (rather than discrete component) based.
Earlier editions (which had more information on Flip-Chip based designs),are
much more useful to those intersted in older PDP-8's (/I /E /L /M /S).
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Bill Richman
Sent: Sunday, January 25, 2004 6:48 PM
To: cctalk(a)classiccmp.org
Subject: PDP Manual on eBay
FYI - looks like a nice book. Tempted to bid on it myself, but I don't
have a PDP. Thought someone else might be interested.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3581863201&categ…
3:39 p.m.
David,
The PDP8/A did not use a microprocessor. It was TTL SSI/MSI like the 8/E,
though
ia different design and packaged more densely. The 8/A replaced some random
logic
with small ROMSs, and later models used semiconductor memory instead of
core.
All subsequent models, e.g., vT78 and DecMate, were microprocessor-based.
--Bill
----- Original Message -----
From: "David V. Corbin" <dvcorbin(a)optonline.net>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk(a)classiccmp.org>
Sent: Sunday, January 25, 2004 3:56 PM
Subject: RE: PDP Manual on eBay
Actually that (I am pretty sure) is a version that
focuses mainly on the
PDP-8/a which was microprocessor (rather than discrete component) based.
Earlier editions (which had more information on Flip-Chip based
designs),are
much more useful to those intersted in older
PDP-8's (/I /E /L /M /S).
4:01 p.m.
My apologies then, should have checked the reference materials. The only
time I was "Face-2-Face" with a PDP-8/A was during a short stint at
Racal-Milgo in Miama (1980-1981). That one definately used semiconductor
memory.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of William Maddox
Sent: Sunday, January 25, 2004 9:39 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: PDP Manual on eBay
David,
The PDP8/A did not use a microprocessor. It was TTL SSI/MSI like the 8/E,
though
ia different design and packaged more densely. The 8/A replaced some random
logic
with small ROMSs, and later models used semiconductor memory instead of
core.
All subsequent models, e.g., vT78 and DecMate, were microprocessor-based.
--Bill
----- Original Message -----
From: "David V. Corbin" <dvcorbin(a)optonline.net>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk(a)classiccmp.org>
Sent: Sunday, January 25, 2004 3:56 PM
Subject: RE: PDP Manual on eBay
Actually that (I am pretty sure) is a version that
focuses mainly on the
PDP-8/a which was microprocessor (rather than discrete component) based.
Earlier editions (which had more information on Flip-Chip based
designs),are
much more useful to those intersted in older
PDP-8's (/I /E /L /M /S).
5:12 p.m.
[...PDP-8s and what they used for computation and
RAM...]
I once owned an 8/F (er, a "pdp 8/f" I think the faceplate said) and it
quite definitely used real ferrite core for RAM. I'm sure of this both
from physical inspection and from its preserving its
contents
faithfully across multi-week-long power-downs.
Whether this was true of all 8/fs or not I have no idea. I do know
that memory was addable and removable (my machine had five of eight
possible banks populated), so presumably it would be possible to
replace a board of core with a board of semiconductor RAM provided you
were careful to present the same interface to the rest of the machine.
I also never looked in enough detail to see whether it used discrete
stock chips, ROMs, custom chips, or what, for its logic. It was made
up of enough boards that I'd have no trouble believing the first.
I no longer have the machine. I gave it to a much more serious
collector quite some years ago, in the late '90s I believe it was.
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse(a)rodents.montreal.qc.ca
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9:56 p.m.
On Sun, Jan 25, 2004 at 11:12:28PM -0500, der Mouse wrote:
That was not an unusual configuration.
[...PDP-8s and
what they used for computation and RAM...]
I once owned an 8/F (er, a "pdp 8/f" I think the faceplate said) and it
quite definitely used real ferrite core for RAM. I'm sure of this both
from physical inspection and from its preserving its contents
faithfully across multi-week-long power-downs. Whether this was true of all 8/fs or not I have no
idea. I do know
that memory was addable and removable (my machine had five of eight
possible banks populated), so presumably it would be possible to
replace a board of core with a board of semiconductor RAM provided you
were careful to present the same interface to the rest of the machine.
DEC and third parties both made MOS memory boards.
I also never looked in enough detail to see whether it
used discrete
stock chips, ROMs, custom chips, or what, for its logic. It was made
up of enough boards that I'd have no trouble believing the first.
The -8/f (like the -8/e and -8/m) use TTL for the bulk of the processor,
along with National Semi and DEC bus drivers (as specified in the small
computer handbook).
-ethan
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