Technology Square

Technology Square in 1994; Building NE43 at lower right

Technology Square was the nickname for MIT building NE43; its formal address was '545 Technology Square', but everyone just called it by the shortened form, Tech Sq.

The Technology Square complex contained other buildings; in about 1968 the Beta building, a virtual clone of the 545 Tech Square building, was built on the other side of the main courtyard, at 575 Tech Square. A Honeywell branch, CISL (probably 'Cambridge Information Systems Laboratory'), where much Multics work was done, was on the third floor of Beta. Computer Corporation of America was housed on the fifth floor of Beta.

Entrance sign

545 Tech Square held Project MAC - later split into the AI Lab and the Laboratory for Computer Science (including the Dynamic Modeling, Mathlab, Macsyma Consortium, and Computer Systems Research - the group which did Multics, and a lot of early Internet work - groups), until they moved to the newly- and purpose-built Stata Center in 2004. These entities housed, for many years, the vast majority of significant computer work at MIT.

Their machine room was always on the top (9th) floor, which was almost all raised floor. The other floors held mostly offices (with occasional interjections, such as the DSSR/RTS group's small machine room, which was on the 5th floor - even though DSSR/RTS itself was housed on the 4th floor).

9th floor layout

Originally, the 9th floor held MIT's second CTSS machine, and the GE-635 and GE-645 of the Multics project.

Later on, space around the outer walls where the CTSS/Multics machines used to be was turned into enclosed offices; the remainder of that space was used to hold the MIT-MC KL10 ITS machine.

Floor plan (click to enlarge)

(A ping-pong table was behind MC, between it and the outer wall at the end of the building; this was later dispensed with, so the space could be used to hold the CSR group's PDP-11/40. Later the /40's CPU was swapped to EECS - they wanted it for a second front end on the EECS DECSYSTEM-20, which was named 'DeepThought' - for a PDP-11/45, which had been the EECS DELPHI machine, on which quite a few years of CS undergrads learned to program. Sic transit gloria mundi.)

The ARPANET IMPs (eventually three of them, in the C/30 generation) were along the outer sidewall where it says '1401'. The MIT-XX DECSYSTEM-20 TOPS-20 machine was installed right next them, along a new wall built approximately where the two pillars are; its disk drives were along the outer wall.

The MIT-DM KA10 ITS machine was between the DM PDP-6 and the MIT-ML KA10 ITS machine, and also along the outer wall behind that PDP-6. ML was mostly along the outer wall (much of it where room 923, which was demolished, was), with its DEC disk drives in front of it. When the KS10 ITS machines arrived, they went where ML used to be.

The Dover was eventually installed between the two doors into the lobby, on that side of the building. Room 922 was cut down, and re-numbered as 925 (MOON's office).

As the other end, the offices 919-921 were done away with, and that all became open raised floor, initially holding various robot arms, the Xerox Graphics Printer, etc, etc; later, CADR LISP machines were there (and elsewhere). The AI ITS KA10 was later replaced with the MIT-OZ TOPS-20 DECSYSTEM-20.

See also

• ITS machine configurations

External links

• SHUT DOWN - old instructions on how to power down everything on the floor
• Philippe Brou's images
  • Entrance to Computer Room - showing the end memory cabinet of the MIT-MC machine in the far background
  • Internet Interface - MIT's original 516 IMP (#6) on the left, with the 316 TIP (#44) on the right; the LSI-11 between them is the MIT-GW
  • LCS 20-60 - MIT-XX
  • ML PDP-10 - back row, from the right: CPU, pager, 4xMD10 memories, RP10? and its DF10?
  • Knight TV Controller - at short wall end
  • Xerox Alto - Tridents of the IFS? (possibly also/or a LISP machine) behind on left, and the 9th floor ping-pong table behind on right
  • MC KL-10 - several images
    • CPU
    • One wing - MF10's; also RH10 and its DF10 at the far end
    • Memories - ARM10 on right, with MF10's behind
    • The other wing - from right, the TM10, its DF10, the DL10, the 'I/O-11' (in blank cabinet), and the first Trident
• Tech Square - description of the entire complex
• MIT leaves behind a rich history in Tech Square
• Computer Resources - from the '1975 MIT Lab for Computer Science Brochure'; it includes some very rare images of the 9th floor machine room
• NE43 Memory Project Forum
• ABC docmentary "What About Tomorrow? - On The Side Of Man" from January 1973 has plenty of footage from inside Tech Square