Terminals and Peripherals


First on our peripheral tour (that's a joke, son), are terminals. Hard copy terminals, to be specific. The first terminal in the collection is the ASR-33 Teletype. This hardy little device was extremely popular on minicomputers and early microcomputers. It is also probably caused more frustration than almost any mechanical computer device around!

ASR 33 The ASR 33

The other hardcopy terminals in the collection are the LA36 DEC Writer and a DG Dasher hardcopy terminal. As the DG is currently stored in my garage (for lack of room in the basement) it has not yet been photographed. But, here's a picture of the LA36:

The LA36 LA36

The collection also has a couple of display terminals, the VT-52 and it's descendant, the immensely popular VT-100. The VT-52 was purchased from the "Second Bytes" used computer store in Milwaukee. The VT100 was obtained as a part of the PDP-11/24 system.

VT-52 The VT-52

The VT-100 serves as the console terminal for most of the PDP-11 systems (I only have power connections enough to run one system at a time).

The VT-100 VT-100


I have quite a collection of peripherals in the collection, but I have not photographed them all. Still, what is shown here is a pretty good sampling.

Tape Drives

First, we have a "classic" 9 Track (800 Bits Per Inch) tape drive, the TU10:

TU10 The TU10

However, because these tape drives were quite expensive to manufacture, less costly drives were invented. The original LINC systems had a 3/4" wide tape on a 4" reel, called LINC Tape. The PDP-12 has a somewhat modern version of LINC Tape. The PDP-11 used a newer version, and DEC named it DEC Tape. It had a capacity of around 256K Bytes.

The TU56 DEC Tape TU56

The unit in the rack just below the TU56 drive itself is the TC-11 controller used to control the TU56 from a PDP-11. It has a special window cut into the panel, so that the lights and switches can be observed.

The DEC Tape and LINC Tape tapes and drives are quite hardy. Most of the drives in the collection still operate, and I am finding the tapes still readable 20 years after they were first written. They are also very noteworthy because they were block addressed, rather than just sequential as was typical of tape devices of the day. In that respect, they were not unlike the current QIC (Quarter Inch Cartridge) tapes sometimes used on home PC's these days.

Disk Drives

There is quite a variety of disk drives in the collection. Some of the disks are hidden behind panels (such as the DEC RC-11 and the disk drives on the DG systems), so there are no pictures of those here. However, here are some of the disk drives I do have pictures of:

RK03 The RK03

These RK03 disk drives are part of my friend Hannes' PDP-11/20 system.

The RK03, which was later replaced by the functionally similar RK05, had a capacity of 1.2 Million words (2.4 MB). It's track to track seek time was a respectable 15ms, with an average seek time of 70ms.

The RK05 RK05

The RK05 soon replaced the RK03. It had the same capacity, but had faster seek times: 10ms track to track, 50ms average. These drives were very very popular on PDP-11 systems (as the RK11 disk subsystem) and on PDP-8/e systems (as the RK8/e disk subsystem). But, time marched on, and the need for disk storage grew, so along came the RK06 and RK07 disk subsystems. I declined an offer for RK06 drives (I was out of room), but the PDP-11/24 system came with two RK07 disk drives. The RK06 had a capacity of 14MB. The RK07 had a capacity of 28MB, with average seek times of 36.5ms.

RK07 The RK07

The RK07 was somewhat large, heavy and expensive. A popular alternative was the RL01 (and RL02) with a capacity of 5.2MB (10.4MB) and average seek speeds of 55ms.

The RL01 RL01

Finally, DEC also had floppy disk drives: the RX01 and RX02. They were used quite a lot on the LSI series of PDP-11 minicomputers.

RX01 The RX01

Other Peripherals

One interesting peripheral I have obtained is an IBM 1627 plotter. Under the covers it is really a CalComp plotter. This same model plotter was also sold by DEC for it's PDP-12 systems. I could use it but, like my friend Paul, I have no plotter interface for my PDP-12 (see my wish list). From it's number, I deduce that it was originally part of an IBM 1620 system. (The 1620 system did it's arithmetic using the adders that were part of it's index registers, using table lookup. For that reason, it was sometimes called the "CADET" computer (for "Can't Add, Doesn't Even Try"). The popular ECAP (Electronic Circuit Analysis Program) was originally written for the 1620. Anyway, here it is:

The 1627 Plotter IBM 1627

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©1996, 2000 Jay R. Jaeger