When I mentioned the chance to buy a 4kW stack for the PDP-8/i for $100...
--- Lawrence LeMay <lemay(a)cs.umn.edu> responded:
> Actually, that's probably a reasonable price.
Foo!
> Core memory boards, probably non-working, have been going for a high price.
I got sniped for a PDP-11 double-core stack this weekend, backplane included,
that went for $38, no reserve.
> Age and a nice visible setup increase the price.
The core stack for a PDP-8(i|L) is older than much of what's on the
market, but none of the good stuff is visible at all on it.
> Now, I havent seen the memory in question. but the pdp8/e core
> memory i've seen is all covered by a clear plastic shield. This
> increases its value as a display piece, as you can easily see
> all the core, and its all protected.
It's hard to describe the arrangement, but the core plane in question
here is a block with two edge-connectors on either side, "dual-height"
as they say, but it's much thicker - let's try bad ASCII art to illustrate...
######## ########
xxxxxxxxxxxxxxxxxx == ######## ########
######## ######## ######## ########
core planes paddle-boards with wire harness
The outside of the core plane part is covered in a "diode matrix", with
a wad of twisted-pair wires that go off to paddle-boards, one for the
sense bits, one for the inhibit bits. The address lines come up the diode
boards, the data comes up and down the paddle-boards.
There are several PCBs with core in the core stack, 4-bits per layer with
an optional parity layer that has one pad of bits and three pads of core-less
X-Y wires. None of this is visible when the plane is assembled, and it's
soldered together with lines of wires going up and down the planes.
> Of course, in order to use the core on a pdp8/? you would need
> a couple of support boards in addition to the core plane board
> itself. I would say that just the core plane, being of a nice
> size, and being very good 'visually' to display, and somewhat
> because its a PDP8 series board (nostalgia value), that its
> probably worth $100 all by itself. If it comes with the 2 support
> boards and the top connector things at that price, then i'd say
> its a bargain.
You are thinking of newer hardware. The pre-OMNIBUS 8's have a wad of
individual, single-height cards that contain the sense-amps and the inhibit
drivers. I have a pile of them from an -8/L that someone else had already
begun to strip for parts before I bought it (it also happens to contain the
only DEC lock that does *not* use the XX2247 key). I'm not worried about
the analog stuff... I need the core.
Of course, as Allison pointed out, I could always stick in a lump of battery-
backed static RAM. I was contemplating building a wiring harness to adapt
an RX8E on the back of either an -8/L (which has 8kW of core out of 12kW in
an expansion cabinet) or on the -8/i. I would use berg connector pins to
stick the wires on the back side of the backplane (to avoid soldering, of
course; but worst case, I just wire-wrap on a connector or two and use
sheilded ribbon to move the signals around.
The joys of restoration in a market of scarcity. :-P
-ethan
_________________________________________________________
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In my limited experience with the PDP-8E, memory seems very difficult to
come by. I'd give my eye teeth for a 32k semiconductor board, but both
semiconductor and core seems to be nowhere.
Jay West
-----Original Message-----
From: Ethan Dicks <ethan_dicks(a)yahoo.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, April 19, 1999 7:05 AM
Subject: How scarce (valuable) is core for the PDP-8?
>
>I have a chance to buy a 4kW core stack for the PDP-8/i (-8/L). It's
>more than I want to pay, $100. My question is, what are these things
>going for these days? I don't really *need* it. The guy selling it
>has more core than this that he saved from a "recycler", but he's in
>it for the money, not out of a love for classic machines. Most of his
>memory, he sells to people who want something to stick on the shelf and
>"ooh" and "aah" at. :-(
>
>So... for those people who have been trying to get core over the past year
>or two, what's it costing? I'm trying to decide if I want to grab this
>stack to put into my -8/i and bring it up to 8kW, an entirely optional
>project (I have all the other parts I would need for the upgrade from a
>PDP-8/L that I got in 1982 that was sold as parts-only, bad core, and most
>of the I/O and part of the CPU missing).
>
>I think he's charging too much, but maybe I'm disconnected with the
>current pricing. I do know that if I pass on it, there are several
>other people who are waiting for this exact piece, so it'll be sold
>one way or the other when I answer him.
>
>OTOH, I do have a broken (20-30 fractured cores) -8/L stack that I've
>contemplated repairing. It's a parity stack, so I can scavenge wire
>and cores from the parity plane (or just use the parity plane intact
>as another bit, then use one pad of broken core to repair the other,
>less damaged pad of broken core). Any thoughts out there on core repair?
>It's 1968 DEC core with, AFAIK a seperate sense and inhibit wire, which
>is both good and bad - good because the cores are larger than three-wire
>core, bad because I'd have to thread up, down and two diagonals.
>
>Of course, I could always sell the broken plane to a collector and use
>the money to fund part of this working stack. So many options. In terms
>of time spent, it's cheaper for me to work a few hours and earn the money
>that the core pirate wants; in terms of lessons learned, repairing a
30-year-
>old core stack would be a big thrill, *if* it worked.
>
>Thanks,
>
>-ethan
>
>
>_________________________________________________________
>Do You Yahoo!?
>Get your free @yahoo.com address at http://mail.yahoo.com
>
>
I'm not sure about the problem you're having with HDToolbox, but what type
of HD controller is in your 2000HD? I remember having problems similar to
what you're experiencing (old Mac SCSI drive not recognized by OS) when I
was using a 2090a in my 2000. When I switched to a 2091, I had no further
problems.
I think the 2091 was standard in the 2000HD, but it might be worth checking
to see if someone has swapped in an old controller...
Just a thought. Good luck.
Mark.
----------------------------------------------------
Amiga / Apple / NeXT / PDP-11 / PS/2
Computing happily on the trailing edge of technology
----------------------------------------------------
At 07:25 PM 4/17/99 -0400, you wrote:
>
>Well, I know about HDToolbox, but there's one problem.
>
>When I try to run HDToolbox, it always says "Driver not installed" in the
>box that is supposed to contain drive information. The HDSetup program
>will get to the point where it is supposed to start formatting &
>partitioning the drive, then just drops back to WorkBench with no
>messages.
>
>Any ideas for this one?
>
>Thanks,
>Kevin
>
>Did something fall into place here for me?
>Does the "RT" in RT-11 happen to stand for Real Time?
It sure does...
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
| Unix Support Engineering Group | (home): mbg!world.std.com |
| Compaq Computer Corporation | addresses need '@' in place of '!' |
| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ |
| Nashua, NH 03062 | "pdp-11 programmer - some assembler |
| (603) 884 1055 | required." - mbg |
+--------------------------------+-------------------------------------+
The mode in which the Shugart SA1400 controllers, after which some of
XEBEC's controllers were patterned, was this ultra-simple model. That may
not have been the only mode, but I've got an 8" drive controller which seems
to work in this way, as it also has no device address switch. I've never
found the identifying logo or whatever, but the S-100 adapter I got with
this setup has a PROM marked "SA1400."
I've also read about this single-target-single initiator mode in the early
papers we used in establishing the SCSI-I standard back in the mid-1980's.
( I had the "privilege" of sitting through a number of the standards
committee meetings on behalf of my employer back then) Clearly, SOME makers
had used this as an operating mode. Multiple disk drives were not that
common among small systems back in those days.
Dick
-----Original Message-----
From: Eric Smith <eric(a)brouhaha.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, April 19, 1999 12:07 AM
Subject: Re: Ancient disk controllers
>> SASI, incidentally was essentially a
>> Single-Target-Single-Initiator SCSI so it wouldn't need a device ID
switch.
>
>SASI supported eight targets. Since there was only one initiator and no
>disconnects, the initiator didn't need an ID. But the target devices still
>needed IDs.
>
>SCSI-1 added arbitration (for multiple initiators), disconnects (and
>reselection), and the 10-byte commands (to support larger devices). I'm
not
>sure whether SASI supported the message phase; that may also be a SCSI-1
>innovation.
>
>Usually a SASI host can deal with SCSI disk drives. Sometimes a SCSI
>host can deal with SASI targets, as long as it restricts itself to the
>SASI commands.
<My dumb question: What is a real time operating system?
<
<Hans Olminkhof
Complex question simplified answer.
An Operating system (environment) that supports tasks that must keep up
with real world events. Timeliness is the key element, either now or within
a known time for actions to occur are often part of the
specification typical use might be process control where pressure,
temperature and ??? are monitored and adjsted to stay withing bounds or
require extremely fast reaction to abrupt changes. Things
that RTOSs have are interrupt driven events and scheduling of lower
priority events for less demanding tasks.
RTS-8 (DEC pdp-8) (sources and docs on the 'net)
RT-11 (dec PDP-11)
Two commercial examples that are well known.
CP/M and believe it or not DOS (there are DOS look alikes that are RT)
can be as well.
Allison
--- Pete Turnbull <pete(a)dunnington.u-net.com> wrote:
> On Apr 19, 5:58, Eric Smith wrote:
>
> > Usually a SASI host can deal with SCSI disk drives. Sometimes a SCSI
> > host can deal with SASI targets, as long as it restricts itself to the
> > SASI commands.
>
> Some old SCSI hosts can, but most modern ones expect to use messages.
I have an ancient driver for monochrome Macs that can be set to old
SCSI<->ST-506 bridges like the Adaptec 4000-series or even a couple of
SASI controllers.
I know I've seen one SASI<->ST-506 bridge - inside the Commodore PET
D9060/D9090 hard drives. There's a Tandon TM602S (or TM603S) inside
the box, a SASI interface to it, then a Commodore "DOS" board that
speaks SASI out one end, IEEE-488 out the other. One of these days,
I'll disassemble the ROMs on the D9060 and look for the part that
reads the 5Mb/7.5Mb jumper and sets up the drive parameters, then patch
in the right numbers for an ST-225 so I can continue to use the thing
after my last 5Mb mechanism dies.
-ethan
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
>> I've installed a filter at my end that should dump most, if not all,
>> messages with OT: in the subject line. However, the point remains that I
>> should not have had to do so in the first place.
Hmm, the problem with that being that occasionally OT conversations are
interesting/meaningful.... what we need is a filter that only starts
dumping OT threads after the first few messages (enough intelligence to
never let *any* 'my language is better than yours', gun laws, ABS
braking etc etc. conversations through would be great too.... :*)
(Hmm, maybe that sounds a bit heavier than it should be... still, it is
Monday morning... ;)
cheers
Jules
>
On Apr 19, 5:58, Eric Smith wrote:
> SCSI-1 added arbitration (for multiple initiators), disconnects (and
> reselection), and the 10-byte commands (to support larger devices). I'm
not
> sure whether SASI supported the message phase; that may also be a SCSI-1
> innovation.
It didn't; messages first appeared in SCSI-1.
> Usually a SASI host can deal with SCSI disk drives. Sometimes a SCSI
> host can deal with SASI targets, as long as it restricts itself to the
> SASI commands.
Some old SCSI hosts can, but most modern ones expect to use messages.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
For those who have never witnessed the diversity and chaos that has been
Paxton's warehouse, pictures taken today during the auction are available at:
http://www.computergarage.org/Garage/Paxton/P0??.JPG (where ?? = 06 thru 42)
The last few are shots of the collective bootie that the local gang took out.
(and yes, its as chaotic as it looks in the pictures!)
I'll probably arrange it into a more normal web page in the next few days.
For my part, I managed to nab a pair of HP 1000F minicomputers (CPU
cabinets only), a Tek 4006 terminal, a DEC TU-81+ tape drive and RA-81 hard
drive, a Freiden computerized postage scale, a case of toner kits for DEC
LN-03/Scriptwriter printers, a Tektronix Type 230 'Digital Unit', an
HP-9000 computer, a DEC MINC-11, and some other assorted goodies.
20 points extra if you can tell us why the unit in this picture:
http://www.computergarage.org/Garage/Paxton/P049.JPG
had enough significance to rank fairly high on my 'nab' list...
More to come...
-jim
---
jimw(a)computergarage.org
The Computer Garage - http://www.computergarage.org
Computer Garage Fax - (503) 646-0174
