Dennis Richie (standing) and Ken Thompson in front of a significant PDP-11 system. The equipment racks (left to right) are :-

• The first rack, which is almost completely obscured by Ken, contains a TU10 tape drive.

• RF11 disk controller. There is a status display panel at the top.

• RK03 disk drives

• TU56 DECtape with spools of tape stored below.

• Additional TU56 DECtape.

• PC11 paper tape reader/punch. There is glimpse of a PDP11/45 (hidden by the second ASR33) under the punch.

• PDP11/20. It's not one of the earliest, since you can see the /20 on the decal. According to Dennis, it's probably the second 11/20 at the labs and contains a KS-11 memory expansion unit (see Odd Comments and Strange Doings in Unix)

• VT01A display (Tektronics 611 storage display) and 4x4 button box

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