Imlac PDS-1

The Imlac PDS-1 kicked off the world of networked graphics workstations. I donated mine to the Vintage Tech Archive. Thanks to Uncle Al for the scanned docs.
	fuzzy image of PDS-1 name plate

According to Jim Davis: The Imlac was a minicomputer (what you'd call a workstation now) that was sort of an expanded PDP-8 with a built in vector display processor. It was programmed in assembly language. Imlac's big product was a phototypsetting system, CES, which took advantage of the raster graphics to offer a kind of WYSIWYG interface for the typesetting. This was before laser printers. From Steve DeRose: What, you never heard of the Imlac? That was the high-end vector display on which FRESS shone: where it could do multi-window WYSIWYG editing of text and graphical hypermedia. Perhaps its best feature was that it used a lightpen instead of a mouse. Pointing to text or menus on the screen and then stomping on the foot-pedal provided a certain catharsis unmatched by the modern mouse button. 4 huge panes full of 9-point text did tax the vector engine's ability to draw little strokes, though.

From L. Peter Deutsch: Yikes! From John Mock: Amusing, though, i haven't heard of a gr'Imlac in decades... Deutsch's response seemed appropriate... We had three at SAIL, on at the C.S. Dept. Library on campus, one at McCarthy's house and i forget where the third on lived. We hacked the Network Graphics Protocol which run off a GT40, on a network UNIX system at Berkeley in 1975. (Hint: That was before BSD meant anything.) 'actually ran display programs on SAIL machine remotely with little or no modification. It was kinda slow compared to setting in front of the old III displays, whose vector character seemed like they were hand-drawn. (And if the diode-ROM-based character drawing wasn't tuned up, equally illegible). The gr'Imlac (pronounced 'grim-lack') was a little more legible, but not alot. Yes, we needed that character RAM; SAIL had approximately 125 printable characters.

Imlac Facts

• Made around 1970 by the Imlac Corporation of Needham, MA (founded 1968).
• Mine is serial number 12.
• Built-in display list processor.
• RAM-based (vectorized?) character set.
• 4096 16-bit words of RAM (core).
• I've heard that the computer is similar to the DEC PDP-8.

Historical Perspective

• DEC 338
• DEC 340
• IBM 2250

Imlac was important in the early days of the internet (then called the ARPAnet) when network graphics protocols were first being considered. They are mentioned in several early RFCs (see links below).

One of the first hypertext systems, FRESS (late 1960's), used an Imlac for display.

The Imlac PDS-1 was the first machine that let you get in trouble for wasting time on the net. From the X Window man page of MazeWar:

MazeWar first appeared at MIT in the early 1970s, using Imlac displays and the ArpaNet network. Legend has it that, at one point during that period, MazeWar was banned by DARPA from the ArpaNet because half of all the packets in a given month were MazeWar packets flying between Stanford and MIT.

MazeWar appeared again at the Xerox Palo Alto Research Center in the late 1970's on the Alto, the first personal computer.

GUI Timeline

• December, 1968: Doug Engelbart describes A Research Center for Augmenting Human Intellect at SRI. The interactive graphical environment he develops is called NLS (oN Line System).
• 1972: Peter Deutsch demos DNLS (Display NLS) on a Imlac PDS-1 and PDP-10 at ICCC.
• 1973: Xerox creates the Alto.
• 1982: Apple creates the Lisa.

State of the Machine

Console

• Front view of damaged CRT
• Side view of damaged CRT

Computer Hardware

• One of the component cards (sort of a flip-chip)
• The CPU and memory rack (desk bottom)

Documention

Printsets

Software

Links to Other Information

• Tom Uban has an Imlac PDS-1D
• 01/05/1971: RFC 86, Proposal for a Network Standard Format for a Data Stream to Control Graphics Display, S.D. Crocker
• 04/18/1971: RFC 126, Graphics Facilities at Ames Research Center, J. McConnell
• 06/08/1971: RFC 174, UCLA Computer Graphics Overview, J. Postel, V.G. Cerf
• 07/13/1971: RFC 190, DEC PDP-10-IMLAC communications system. L.P. Deutsch.
• 07/13/1971: RFR 191, Graphics implementation and conceptualization at Augmentation Research Center, C.H. Irby
• 10/08/1971: RFR 249, Coordination of equipment and supplies purchase, R.F. Borelli
• 03/24/1972: RFR 321, CBI Networking Activity at MITRE, P.M. Karp
• 07/12/1972: RFC 372, Notes on a Converation with Bob Kahn at the ICCC, R.W. Watson
• 07/14/1972: RFC 373, Arbitrary Character Sets, J. McCarthy
• 09/22/1972: RFC 398, ICP Sockets, J.R. Pickens, E. Faeh
• 08/18/1978: Imlac Introduces the Dynagraphic Graphics Terminal (in German)
• Ward Cunningham at an Imlac

More Images

• The backplane wiring (desktop removed)
• Close-up of back of memory susbsystem
• Big honkin' connectors