Unknown: Ken creates `Space Travel'. It was first written on Multics, then transliterated into Fortran for GECOS, then Ken and Dennis rewrote Space Travel to run on the PDP-7 [http://cm.bell-labs.com/cm/cs/who/dmr/hist.html]

Mid-year: Bell Labs finally withdraws from the Multics project. Dennis says: “It was pretty obvious many months in advance that the support was likely to go away, and the machine stayed around for months after.” [QCU pg 8]

April, May, June: Ken is interested in writing a file system. Dennis says: “The interest was older than this. He did experiments with simulation of paging on Multics, for example. He also wrote a rudimentary, completely stand-alone system for the Multics machine that achieved the equivalent of “Hello World” but gave it up when it became obvious that the hardware would not last.” [QCU pg 8]

Mid-year: Ken brings the file system to life on the PDP-7 in a month [QCU pg 10]

Unknown: Ken develops the B language. Dennis says: “By the time B was developed, PDP-7 Unix was a 2-user system that already did a basic core of ancestral commands and was self-supporting (development done on itself). So during the next months, extending into 1970, a useful programming environment visibly ancestral to current Unix was developed. B was just a part of this.” [QCU pg 34], [http://cm.bell-labs.com/cm/cs/who/dmr/chist.html]

Unknown: Peter Neumann coins the term `Unics', which is subsequently changed to `Unix' [QCU pg 9]

Unknown: Alternatively, Brian Kernighan suggests the name `Unix' [http://cm.bell-labs.com/cm/cs/who/dmr/hist.html]

Dennis says: “I think the Neumann connection was an invention of my own fevered brain. I wasn't sure who created the name and I assumed Peter because of his propensity for puns. He has since denied involvement and Brian has claimed it, so I think things are as certain as they can be at this point.”

Mid-year: The PDP-11/20 is ordered, but it arrives with no disk drives as they were not ready yet [QCU pg 35], [http://cm.bell-labs.com/cm/cs/who/dmr/hist.html]

Unknown: Ken has recoded the Unix kernel and some commands in PDP-11 assembly code. Dennis writes: “Much of the recoding occurred before the disk was delivered. The basic system was running and executing commands, with a basic shell, cp and whatnot. The 12KWords were divided into 8KB for the system code and data, 8KB for running user programs, 8KB for an in-memory file system. This all used a cross-assembler written in B that ran on the PDP-7 and generated the -11 object programs.” [http://cm.bell-labs.com/cm/cs/who/dmr/chist.html]

3 months later: The disks for the PDP-11/20 arrive [http://cm.bell-labs.com/cm/cs/who/dmr/chist.html]

January-March: PDP-11 version largely rewritten during this period, but was not truly self-supporting. [http://cm.bell-labs.com/cm/cs/who/dmr/notes.html]

February: PDP-11 Unix beccomes “operational” [http://cm.bell-labs.com/cm/cs/who/dmr/cacm.html]

Throughout 1971: Dennis extends B to be NB [http://cm.bell-labs.com/cm/cs/who/dmr/chist.html]

Spring: roff rewritten in PDP-11 assembler language, starting from the PDP-7 version that had been transliterated from McIlroy's BCPL version on Multics, which had in turn been inspired by J. Saltzer's runoff program on CTSS [http://cm.bell-labs.com/cm/cs/who/dmr/hist.html]

November: First Edition manuals were published [QCU pg 43]

January: The Labs issues a technical memorandum, written by Ken, describing the B language on the PDP-11 [http://cm.bell-labs.com/cm/cs/who/dmr/kbman.html]

January-May: Most of the 0405-magic binaries on the s2-bits tap archive, using the 1st Edition API. date(1) has 1971 as its epoch. [timestamps on files in the tap archive]

March: First manual for cc(1) [QCU pg 48]

March: UNIX is running on at least 5 PDP-11/20s [http://cm.bell-labs.com/cm/cs/who/dmr/notes.html]

June: DEC starts to ship the PDP-11/45. The Labs purchases one soon after this [http://www.village.org/pdp11/faq.pages/11model.html]

June: Second Edition manuals were published. 10 UNIX installations [QCU pg 43]

June-July: The C compiler binaries and associated utilities (as, nm, size, ld, un) on the s2-bits tap archive, with 0407-magic and using the 2nd Edition API. The files in the last1120c C compiler are contemporaneous. [timestamps on files in the tap archives]

Unknown: Ken adds pipes to the assembly-language version of the kernel [QCU pg 51], [http://cm.bell-labs.com/cm/cs/who/dmr/hist.html]

December: The prestructc C compiler sources. This compiler assumes a load address of 0, unlike last1120c which has 040000. This implies that the kernel now used the 11/45 memory management. [timestamps on files in the tap archive]

February: Third Edition manuals were published. 16 UNIX installations [QCU pg 43] Kernel is still the assembly-language version [private email from dmr dated 7 Jan 1999]

August: the `nsys' kernel in the PUPS archive, written in C. The source code uses structures; the C compiler must therefore have supported them by now. [timestamps on the files]

September: The C version of the kernel is adopted over the assembly-language version [private email from dmr dated 18 Jan 1999]

October: First UNIX paper by Ken and Dennis, presented by Ken at the Fourth ACM Symposium on Operating Systems Principles [http://cm.bell-labs.com/cm/cs/who/dmr/cacm.html]

November: Fourth Edition manuals were published [QCU pg 43]