>Chuck McManis <cmcmanis_at_mcmanis.com> wrote:
>>Megan, was that a "long" 8/e or a "short" 8/e you recovered in your haul?
>>If it was a long one could you take a couple of pictures of the cover for
>>me?
>What do you mean by a "long" 8/e... I thought the long box was the
>8/e and the short one (what Allison has) an 8/f.
I know that folks here have traiditionally objected to outside FAQ's
when instead the issue could be resolved by dozens of E-mails, but in
this case Doug Jone's *PDP-8 Summary of Models and Options* answers
the question of 8/E vs 8/F quite nicely:
Subject: What is a PDP-8/E?
Date of introduction: 1970 (during or before August).
Date of withdrawal: 1978.
Also known as:
PDP-8/OEM
Industrial-8 (with a red color scheme)
LAB-8/E (with a green color scheme)
Price: $6,500
Technology: SSI and MSI TTL logic were used on these boards, and the
entire CPU fit on 3 boards. Nominally, these were DEC M-series
flip Chip modules, but in a new large format, quad-high (10.5
inch), extended-length (9 inch, including card-edge connector,
excluding handles). The terms used for board height and length
are based on the original working assumption that all flip-chips
were plugged horizontally into a vertially mounted card-edge
connector. On the PDP-8/E, the cards were plugged vertically
down into a horizontally mounted connector, so many users
incorrectly refer to these boards as quad-wide double-high.
Interconnection between boards was through a new bus, the OMNIBUS.
This eliminated the need for a wire-wrapped backplane, since all
slots in the bus were wired identically. A new line of peripheral
interfaces was produced, most being single cards that could be
plugged directly into the inside the main enclosure. These
included a set of posibus adapters allowing use of older
peripherals on the new machine.
Interboard connectors were needed for some multiboard options,
including the CPU and memory subsystems. These used standard
36-pin backplane connectors on the opposite side of the board
from the backplane. Some boards, notably memory boards, had a
total of 8 connector fingers, 4 for the omnibus and 4 for
interboard connectors.
The core memory cycle time was 1.2 or 1.4 microseconds, depending
on whether a read-modify-write cycle was involved (a jumper would
slow all cycles to 1.4 microseconds). A 4K core plane was
packaged on a single quad-wide double-high board, with most of
the drive electronics packed onto two adjacent boards. Soon after
the machine was introduced, an 8K core plane was released in the
same format.
Reason for introduction: The cost of the PDP-8/I and PDP-8/L was
dominated by the cost of the interconnect wiring, and this cost
was high as a result of the use of small circuit boards. By
packing a larger number of chips per board, similar function
could be attained in a smaller volume because less interboard
communication was required. The PDP-8/E exploited this to achieve
a new low in cost while attaining a new high in performance.
Reason for withdrawal: This machine was slowly displaced by the PDP-8/A
as the market for large PDP-8 configurations declined in the face
of pressure from 16 bit mini and microcomputers.
Compatability: As with the PDP-8/I and PDP-8/L, there are no limits on
the combination of IAC and rotate instructions. Unlike the early
machines, basic Group 3 OPR operations for loading and storing
the MQ register work even if there is no extended arithmetic
element. Finally, a new instruction was added, BSW; this swaps
the left and right bytes in AC, and is encoded as a Group 1 OPR
instruction using the "double the shift count bit".
An odd quirk of this machine is that the RAL RAR combination ands
the AC with the op-code, and the RTR RTL combination does an
effective address computation loading the high 5 bits of AC with
the current page and the lower bits of AC with the address field
of the instruction itself!
The EAE has a new mode, mode B. Previous EAE designs were
single-mode. Mode B supports a large set of 24 bit operations
and a somewhat more rational set of shift operations than the
standard EAE. All prior EAE designs would hang on the microcoded
CLA NMI (clear/normalize) instruction applied to a nonzero AC.
This instruction is redefined to be a mode changing instruction
on the 8/E.
Standard configuration: A CPU with 4K of memory, plus 110 baud current
loop teletype interface. Both a rack-mount table-top versions
were sold (both 9" high by 19" wide by 21" deep). The rack mount
version was mounted on slides for easy maintenance. The OMNIBUS
backplane was on the bottom, with boards inserted from the top.
The PDP-8/OEM had a turn-key front panel, no core, 256 words of
ROM and 256 words of RAM, and was priced at $2800 in lots of 100.
The standard OMNIBUS backplane had 20 slots, with no fixed
assignments, but the following conventional uses; certain board
sets were jumpered together (shown with brackets) and therefore
were required to be adjacent to each other:
-- KC8E programmer's console (lights and switches)
-- M8300 \_ KK8E CPU registers
-- M8310 / KK8E CPU control
--
--
-- M833 - Timing board (system clock)
-- M865 - KL8E console terminal interface.
--
--
-- -- space for more peripherals
--
--
-- M849 - shield to isolate memory from CPU
-- G104 \
-- H220 > MM8E 4K memory
-- G227 /
--
-- -- space for more memory
--
-- M8320 - KK8E Bus terminator
Most of the early boards with 3 digit numbers were defective
in one way or another, and the corrected boards added a trailing
zero. Thus, the M833 was generally replaced with an M8330, and
the M865 was replaced with the M8650.
Expandability: The following are among the OMNIBUS boards that could be
added internally:
-- M8650 - KL8E RS232 or current loop serial interface.
-- M8340 \_ Extended arithmetic element.
-- M8341 / (must be attached in two slots between CPU and M833.
-- M8350 - KA8E posibus interface (excluding DMA transfers).
-- M8360 - KD8E data break interface (one per DMA device).
-- M837 - KM8E memory extension control (needed for over 4K).
-- M840 - PC8E high speed paper tape reader-punch interface.
-- M842 - XY8E X/Y plotter control.
-- M843 - CR8E card reader interface.
There were many other internal options. There was room in the
basic box for another 20 slot backplane; taking into account the
2 slots occupied by the M935 bridge between the two backplanes,
this allowed 38 slots, and a second box could be added to
accomodate another 38 slot backplane, bridged to the first box by
a pair of BC08H OMNIBUS extension cables.
Given a M837 memory extension control, additional memory could be
added in increments of 4K by adding G104, H220, G227 triplets.
The suggested arrangement of boards on the OMNIBUS always
maintained the M849 shield between memory other options. The
one exception was that the M8350 KA8E and M8360 KD8E external
posibus interfaces were typically placed at the end of the
OMNIBUS right before the terminator.
The following options were introduced later, and there were many
options offered by third party suppliers.
-- G111 \
-- H212 > MM8EJ 8K memory
-- G233 /
-- M8357 -- RX8E interface to RX01/02 8" diskette drives.
-- M7104 \
-- M7105 > RK8E RK05 Disk Interface
-- M7106 /
-- M8321 \
-- M8322 \ TM8E Magtape control for 9 track tape.
-- M8323 /
-- M8327 /
Survival: It is still fairly common to find PDP-8/E systems on the
surplus market, recently removed from service and in working
condition or very close to it. A modest number are still in
service doing their orignal jobs, and there is still a limited
amount of commercial support from both DEC and third-party vendors.
------------------------------
Subject: What is a PDP-8/F?
Date of introduction: 1972.
Date of withdrawal: 1978.
Technology: an OMNIBUS machine, as with the PDP-8/E. First use
of a switching power supply in the PDP-8 family.
Reason for introduction: The PDP-8/E had a large enough box and a large
enough power supply to accomodate a large configuration. By
shortening the box and putting in a small switching power supply,
a lower cost OMNIBUS machine was possible.
Reason for withdrawal: The PDP-8/A 800 displaced this machine, providing
similar expansion capability at a lower cost.
Compatability: The PDP-8/F used the PDP-8/E CPU and peripherals.
Standard configuration: Identical to the PDP-8/E, except that the KC8E
front anel was replaced with a KC8M front panel that had LEDs
instead of incandescent lights; this front panel could also be
installed on PDP-8/E systems, but the PDP-8/E front panel could
not be used on a PDP-8/F because of the lack of a +8 supply for
the lights. The original PDP-8/F box had a defective power
supply, but a revised (slightly larger) box corrected this
problem.
With the dintroduction of the M8330, DEC began to require that
this board be placed adjacent to the KC8x front panel, although
many OMNIBUS PDP-8 systems continued to be configured (by users)
with the M8330 elsewhere on the bus. As a result, the suggested
order of boards on the omnibus began with:
-- KC8E programmer's console (lights and switches)
-- M8330 - Timing board (system clock)
-- M8340 \_ optional EAE board 1
-- M8341 / optional EAE board 2
-- M8310 \_ KK8E CPU control
-- M8300 / KK8E CPU registers
-- M837 - Extended Memory & Time Share control
Expandability: This machine could be expanded using all PDP-8/E OMNIBUS
peripherals, including the external expansion chassis. The
relatively small internal power supply and the lack of room for
a 20 slot bus expander inside the first box were the only
limitations. There were minor compatability problems with some
options, for example, the power-fail auto-restart card, as
originally sold, was incompatable with the PDP-8/F power supply.
Survival: As with the PDP-8/E, these machines are moderately common on
the surplus market, and frequently in working condition.
--
Tim Shoppa Email: shoppa_at_trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Received on Fri Apr 09 1999 - 19:21:51 BST