10 Aug
2020
10 Aug
'20
11:08 p.m.
On 2020, Aug 10, at 10:02 AM, Noel Chiappa
<jnc(a)mercury.lcs.mit.edu> wrote:
“A pain to run” and “tense” indeed! The Dover printing system was an Alto (6 MIPs
<microinstructions>) driving “Orbit” hardware about half the size of the Alto
itself*, driving the raster video to the printer. The hardware was called “orbit” because
it could directly “OR” bits into the raster image, rather than requiring read-modify-write
cycles. “Spruce” was the spooler and printer driver that ran on the Alto. Evidently the
hardware is a typical Butler Lampson knife edge design up in the corner of what was
possible, implemented by Bob Sproull and Severo Ornstein. Additional software by Dan
Swinehart.
There’s a page about this in https://bwlampson.site/38-AltoSoftware/Abstract.html
<https://bwlampson.site/38-AltoSoftware/Abstract.html> and a patent
https://patents.google.com/patent/US4203154
<https://patents.google.com/patent/US4203154>. I have a feeling I’ve seen a longer
description of Orbit somewhere but I can’t remember where.
Like most Stanford folks of the era I printed my thesis on one, assisted about 1 AM by
Lyle Ramshaw who knew where to get a new drum for the printer.
In any event, a vast improvement over the XGP and a godsend for those of us who
<didn’t> have a phototypesetter.
* An earlier one-off called EARS had printer hardware about 3 times the size of the
attached Alto. That one was font-image based. To do things like lines and graphics the
software constructed custom font glyphs to make up the image.
From: Lars Brinkhoff
I haven't investigated it thoroughly, but I
do see a file .DOVR.;.SPOOL
8 written in C by Eliot Moss.
...
When sending to the DOVER, the spooler waits until Spruce is
free before sending another file.
Ah, so there was a spooler on the ITS machine as well; I didn't know/remember
that.
I checked on CSR, and it did use TFTP to send it to the Alto spooler:
HOST MIT-SPOOLER, LCS 2/200,SERVER,TFTPSP,ALTO,[SPOOLER]
I vaguely recall the Dover being named 'Spruce', but that name wasn't in
the
host table... I have this vague memory that 'MIT-Spooler' was the Alto which
prove the Dover, but now that I think about it, it might have been another one
(which ran only TFTP->EFTP spooler software). IIRC the Dover as a pain to run,
it required a very high bit rate, and the software to massage it was very
tense; so it may have made sense to do the TFTP->EFTP (I'm pretty sure the
vanilla Dover spoke EFTP, but maybe I'm wrong, and it used the PUP stream
protocol) in another machine.
It'd be interesting to look at the Dover spooler on ITS, and see if/how one
got to the CHAOS network from C - and if so, how it identified the protocol
translating box.
Noel