PDP-11/53 – Overview

PDP-11/53.

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I picked up this PDP-11/53 in Feb 2014. You can read a little about it here.

Case/Chassis.

Somewhat unorthodox to say the least but strangely practical. It appears that a previous owner has taken the card cage from a DEC chassis such as a BA-23 and mounted it in a 19″ cabinet. There is space above the card cage for a couple of full-height 5.25″ drives.

06deb3285e7f43917474be0687d2ae7dAt the back.

I haven’t followed the internal wiring through yet and so I haven’t found out why there are two mains sockets. When I run the machine I connect to the socket on the main PSU and use the switch on the back.

The card cage is completely exposed as you can see. Currently there is plenty of space for expansion.

Above the card cage is the space of drives and to the left of that an aluminium plate with 2, 25 way serial connectors. These are connected to the two serial ports on the processor board. One for the console the other is labelled “Printer” but is a general SIO. These are known as SLU0 and SLU1.

The Cards.

My machine has the following cards…

  • M7554 – CPU – KDJ11-DA Q J11 CPU 15MHz, 512-Kbyte RAM, 2 SLUs, LTC
  • M7551 – CA – Memory – MSV11-QC Q 4-Mbyte 22-bit parity/CSR MOS RAM
  • M7555 – Disk controller – RQDX3 Q MFM Winchester and floppy disk controller (RX50/RX33/RD50-54/RD31/RD32/RD33)
  • M7516 – Ethernet – DELQA-M Q Ethernet interface (replaces DEQNA)
  • M7546 – TK50 – TQK50-AA Q TMSCP controller for TK50 tape unit.