Pertec T8640A Tape Transport

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I have a Pertec T8640A Tape Transport that is now working nicely on a QBUS PDP-11 system.

While I still have a lot to learn about the operation of magtape systems (and their advantages and limitations), I am now able to successfully “INItialize”, write to and read from magtapes in this Tape Transport.

This Tape Transport is currently mounted in a full-height DEC rack. The rack also has a General Robotics QBUS chassis in it, as well as an MPI SMD hard drive (Model 9448). The SMD drive actually has a fixed hard drive and a removeable cartridge drive in the one enclosure. I have not yet got the SMD drive working.

The QBUS chassis is fairly well equipped. It includes:

  • M8192 processor
  • [RAM board]
  • 2 x Webster terminal multiplexers
  • 2 x DEC DLV11-J 4-port SLU board
  • An Emulex SC02 board to support the SMD drive
  • An Emulex TC01 board to support the Pertec T8640A Tape Transort

I assume this Tape Transport once formed part of this PDP-11 system, but I have no way to verify this. The same rack also has one vacant set of rack slides in it (perhaps for an RX01/RX02 drive).

Unfortunately the QBUS chassis does not have a tape controller interface board in it – presumably this has been removed since the system was decommissioned.

The Tape Transport has 3 x 36-pin edge connectors on it. An Emulex cable kit connects 2 x 40-way ribbon cables to these edge connectors. At the other end of each of the Emulex cables is a 40-pin header connector (so two 40-pin header connectors in total). These two header connectors have handwritten notes on them that say respectively “long board” and “small board”, suggesting that they perhaps connected to a 2-board interface of some kind?

I am only at the early stages of attempting to get this drive running.

My first task is to figure out how this was connected to the QBUS PDP-11. I don’t know whether the two 40-pin connectors would have connected directly to a QBUS board (if so, which model?), or whether there was perhaps an external Pertec or Emulex Tape Formatter cabled between a QBUS board and the Tape Transport.

To complicate things a little, I also found an external Pertec Tape Formatter nearby. I suspect this is probably from a different system, as it has rack-mount slides on it that don’t match the vacant slides in the cabinet.

Any information about how this Tape Transport connects to a QBUS PDP-11 would be very welcome!

Photo Gallery

Here are some photos of the Tape Transport and the rack in which it was found.

Here are some photos of the Pertec Formatter (I am not sure if this is part of this system).

Manuals

I have the following hard-copy manuals:

  • Models T8640A and T8660A Synchronous Write Synchronous Read Tape Transports, Operating and Service Manual No. 103381
  • NRZI Formatter Model F8X9, Operating and Service Manual No. 101600

Tape Transport

The Tape Transport has 3 x 36-pin edge connectors numbered J101, J102 and J103.

The diagram on the right shows the pinouts for these connectors. It is page 2-6 from Manual 103881.

Formatter

Unfortunately this Formatter does not have any manufacturer name or model number on it, except for the “Pertec” badge on the front panel. It does however look very similar to the formatter shown in the F8X9 Manual listed above. So for the time being I assume that is what it is.

The F8X9 Formatter has 2 x 100-pin edge connectors numbered J101 and J102. J101 connects the Formatter to the Controller. J102 connects the Formatter to the Tape Transport.

The diagram on the right shows the pinouts for these connectors. It is page 2-4 from Manual 101600.

“Pertec Interface”

I am aware that tape drives on PDP-11 systems usually have two 50-pin header connectors (referred to as the “P1” and “P2” connectors).

Chuck Guzis has a webpage that describes the pinouts for the Pertec Interface.

A typical interface board for tape drives is the Dilog DQ132 board.

Loading RT-11 on to magtape

Copying RT-11 on to the magtape was easy.

Here are the commands:

  • INI MT0:
  • COPY/SYSTEM DD0: MT0:/POSITION:-1

However the COPY/BOOT command (COPY/BOOT MT0:RT11SJ.SYS MT0:) does not work. Need to work out how to make a magtape bootable.

Next Steps

At this stage I am not sure how to wire the DQ132 -> Formatter -> Tape Transport.

Perhaps these items are not compatible with each other?

More research is needed here.