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| An early PDS-4 at RAL (from here) |
So let's pick up where we left off, shall we?
Peripherals
Of course, a computer's not all that useful without ways of getting information into and out of it. The PDS-1 had a decent set of peripherals available for a machine that was intended to be a smart terminal.Storage
The staple of any computer in that day was Paper Tape. Simple, durable, and foolproof though quite slow, paper tape (via the PTP-1 option) was a good way to store programs and data for the PDS-1. The REL-1 option offered cassette-tape based storage. There weren't too many other local storage options -- in many cases program and data storage was provided by a larger remote host (a PDP-10 or PDP-11 or an IBM mainframe) that the PDS-1 was linked to over an asynchronous serial (usually RS-232) interface.The PDS-1D introduced a removable disk option (the IODISC 2002) with a capacity of up to 48 million bits (6MB or 3MW). I've read anecdotal reports that these drives were not particularly reliable, and I do not know how many of them were actually used.
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| The IODISC 2002 removable pack drive |
Input
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| The Imlac PDS-1D Keyboard (mine) |
Software
The PDS-1 was used for all manner of applications, most of which have been lost to the mists of time. It was commonly used as a terminal, and several terminal emulation packages were available (probably the most popular was of the Tektronix 4010). |
| An Imlac display, showing a circuit design application (from here) |
Applications for graphical editing of circuit designs (shown above) were available, as was a graphical frontend for FRESS, an early hypertext document editing system. There were compiler packages available for FORTRAN which was (understandably) very slow, and the usual suite of assemblers, linkers, and other utilities.
But of course no discussion of the Imlac would be complete without covering Maze War, which may be the first multiplayer 3D-shooter ever created. Played between two Imlacs linked together, or between multiple Imlacs linked to a larger PDP-10 host, Maze War pitted players against each other in a 3D Maze (as might be inferred from the game's name). Players hunted each other down and the last man standing was the winner.
Maze War started on PDS-1s at NASA in the early 70s. Tons of information about the original Maze War and its many many offspring can be found on the DigiBarn site here.
Other Imlac Computers
The PDS-1 was quickly followed by several other models. Some of these were simple revisions, while some had major enhancements over the original. Unfortunately, information is very scarce on many of these -- if you have any information about them, please do drop me a line! |
| An Imlac PDS-4 |
- PDS-1D: Introduced around 1972, this was a cleaner design of the PDS-1. It's rumored that the "D" stood for "Density" as the PDS-1D had a more dense configuration of components, allowing for greater expansion. This is the Imlac model that I will be working on restoring over the coming weeks and months.
- PDS-1G: Introduced in 1973. I can find nothing of substance about this model, other than that it existed.
- PDS-4: Introduced in 1974. A faster machine capable of refreshing many more vectors in the same amount of time as the PDS-1D; it also had hardware support for mirroring and rotation (in 90 degree increments) better scaling support, support for variable beam intensities and blinking (very, very important!) I have very little information about this machine, other than an instruction cheat-sheet. The instruction set is very similar to the PDS-1 series.
- Imlac Dynagraphics "Series II" Terminals. In 1979, Imlac was bought out by Hazeltine (a maker of terminals) and this appears to be the last terminal made with the Imlac name on it. From Wikipedia: "It had 2Kx2K resolution, 192 kilobytes of ram, and an 8086 microprocessor, all inside the monitor unit."
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