[COFF] Butler Lampson's 1973 Xerox PARC memo "Why Alto?"

[Noel Chiappa]

    > From: steve jenkin

    > What struck me reading this is the estimated price (~$10K) to build an
    > .. [ a note elsewhere says $4,000 on 128KB of RAM. 4k-bit or 16-kbit
    > chips? unsure ]

16K (4116) - at least, in the Alto II I have images of. Maxc used 1103's
(1K), but they were a few years before the Alto.


    > I believe the first "PDP-11" bought by 127 at Bell Labs was ~$65k fully
    > configured

I got out my August 1971 -11/20 price sheet, and that sounds about right. The
machine had "24K bytes of core memory .. and a disk with 1K blocks (512K
bytes ... a single .5 MB disk .. every few hours' work by the typists meant
pushing out more information onto DECtape, because of the very small disk."
("The Evolution of the Unix Time-sharing System"):

 11,450	Basic machine CPU + 8KB memory
  6,000	16KB memory (maybe 7,000, if MM11-F)
  4,000	TC11 DECtape controller
  4,700	TU56 DECtape transport
  5,000	RF11 controller
  9,000	RS11 drive
  3,900	PC11 paper tape
-------
 44,050

(Although Bell probably got a discount?)

The machine later had an RK03:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1/u0.s

but that wasn't there initially (they are 2.4MB, larger than the stated
disk); it cost 5,900 (RK11 controller) + 9,000 (RK03 drive).

Also, no signs of the KE11-A in the V1 code (1,900 when it eventually
appeared). The machine had extra serial lines (on DC11's), but they weren't
much; 750 per line.

    > Why the price difference?

Memory was part of it. The -11/20 used core; $9,000 for the memory alone.

Also, the machine was a generation older, the first DEC machine built out of
IC's - all SSI. (It wasn't micro-coded; rather, a state machine. Cheap PROM
and SRAM didn't exist yet.)

	Noel