LINC: Laboratory INstrument Computer

Here follows the text of a message sent out on the Internet to 12-bit computer enthusiasts on 9 June 1992. An article of the same title, based on this, was written and illustrated by John Cook of MIT-RLE (Research Laboratory of Electronics) and printed in RLE-currents Volume 6 Number 1 issued Fall 1992.

Subject: Lights out for last LINC

Time is running out for what we believe is the last running LINC. The LINC (Laboratory INstrument Computer) was designed by Wes Clark in 1962 and may be one of the first "Personal Computers". About 60 of them were built in the summer of 1963 at an MIT "Summer Camp" where researchers from across the country met to put together computers that they could use right in their laboratory - a novel idea at that time of batch-processing in the central Computer Center.

The LINC is built with Digital Equipment Corporation modules - that was how their business started, before they actually built computer themselves - using diode-transistor and diode-capacitor gate logic. Word size was 12 bits, CISC architecture (in contrast to the PDP-8, which is a RISC architecture). Originally the LINC had 1k (yes, thats 1024 words) of core memory, later expanded to 2k.

The LINC is designed for interactive use via Graphical User Interface, with a 256 x 256 CRT display and four `knobs' (the equivalent of a mouse in those days) to enter variable parameters. The Soroban keyboard, for alpha-numeric entry, has keys which lock down when pressed, and pop back up when the computer has read them, thereby solving the problem of type-ahead! The screen editor of LAP-6 (LINC Assembly Program) is integrated with the Assembler and File System. Removable media - two LINCtape drives, of course. The predecessor of DECtape, each spool holds 512 blocks of 256 12-bit words, or 512 bytes - the characters (upper-case, plus various greek and math symbols) fit into 6 bits.

In later years, DEC mounted a LINC and a PDP-8 in the same cabinet and called it a PDP-12, but that's a horse of a different (green) color. Ours is the original blue, and will probably be decommissioned within the month, after 28 years of almost daily service doing what a LINC does best - gathering real-time data, processing and displaying results for the scientist.

Any LINC afficianados out there?

Postscript

Picture of LINC JPEG image, 20k
Later that summer (August 1992) John Cook, RLE photographer, came over to record photographically the retirement party for the LINC. The front panel is in the center with LINCtapes and CRT, Soroban keyboard at the bottom - the CPU itself is a large rack out of sight. From left to right, John Guinan, David Steffens, Ishmael Stefanov-Wagner, Nelson Kiang. EPL Engineers David and Ishmael may be the last persons to have written LINC code, with program development continuing into the 1980s.

The Eaton-Peabody Laboratory LINC was finally transferred to the MIT Museum on 15 August 1995. When it left here, it was still in operable condition. Engineering drawings and historically significant correspondence were given over to the MIT Archives.


Corrections, additions or comments?
Send email (if supported by your browser) to the author, ijs@mit.edu.
Original 27 October, 1995
Last Modified: Jul 21 07:36 EDT 1998 / ijs@mit.edu