PDP-11/05 and Friends

Quite a lot of PDP-11 and similar computers were used at the Laboratory over a long period of time.


This photo of a PDP-11/15 in use at Daresbury dates from 1973. Note the well populated CAMAC crate above it.


This looks like a different model in the Daresbury machine room in 1981.

PDP-11 unknown model

PDP-11/05 SN 8204

Some more pictures and facts for the PDP-11/05 at Daresbury in 1974.

This PDP is serial number 8204 built on 6/11/1974.


The next two pictures are from Dave Cable taken at the British Association of Science mini festival on 4/10/2009. For more pictures see Dave's Flickr site.

PDP-11/05 a PDP-11/05 b


M7260Data paths module
M7261Control logic module
G110purpose not known
G2318K decode latch
H2148K 16-bit stack


We have recently found this machine which was used for data acquisition on the SRS. It looks like an LSI-11/23 with M-8186 KDF11-A CPU board from c.1981, so is probably a 22 bit machine. This had a 3.3 MHz clock.

The LSI-11 was manufactured from 1979 and intended as the successor of the PDP-11/03. It was based on the F-11 chipset, it had a double height KDF11-A processor card. It has a Q-Bus back plane allowing custom cards to be slotted into the chassis. The memory management was 22 bit (4 MB addressing space), but in some revisions (KDF11-A Rev. A) only 18 lines were used. The LSI-11/23 instruction set consists of 97 standard and 46 optional floating-point instructions. The microcycle time of the CPU is around 300 ns.


LSI-11/23 Modules

M-8186 (KDF11-A cpu)M-7504 (ethernet)
DILOG (unknown)AXV21 (unknown)
M-8043 (4-line async to serial link)SensionLtd. PCB 820C (unknown)
M-8059 KC (MOS memory)HYTEC 1104-23 CAMAC interface card

The KDF11-A module has four 40-pin sockets for the chipset. One is for the DCF11 two chip hybrid (21-15541-AB data path and 23-001C7 control chip), one's for the KTF11 MMU option (21-15542-01) and one's for the KEF11 floating point micro-code option (23-002C7 and 23-003C7, another two chip carrier). The MMU must be installed to use the FPP option). Ours has all three. This works with 18 and probably 22 bit addressing.

KDF11-A cpu

This system would have run under the RT-11 O/S. We have the accompanying disc unit with RT-11 base O/S 8 inch floppy.

We are currently seeking more information about CAMAC. The HYTEC 1104 interface card would have connected to a HYTEC 1000 executive crate controller.


A second similar machine was rescued on 9/11/2010. The cards in this machine indicates that it is from around 1982, but it may be as late as 1984.

LSI-11/23 Modules

M-8186 (KDF11-A cpu)M-7504 DEQNA (ethernet)
DILOG 57086B (unknown)(unknown)
M-8043 (4-line async to serial link)SensionLtd. PCB 820C (unknown)
M-8059 KF (128k MOS memory)Technical Magic (unknown)

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