From mboxrd@z Thu Jan  1 00:00:00 1970
From: tytso at mit.edu (Theodore Y. Ts'o)
Date: Mon, 9 Jul 2018 01:23:33 -0400
Subject: [COFF] Other OSes?
In-Reply-To: <3bcafd7f-26be-8770-c754-b179e9cff4a5@spamtrap.tnetconsulting.net>
References: <82df833ae2a587b386b4154fc6051356a3510b19@webmail.yaccman.com>
 <129a13eb-de93-3d6b-b7b5-d0df13e60c87@spamtrap.tnetconsulting.net>
 <20180709015650.GA29373@thunk.org>
 <3bcafd7f-26be-8770-c754-b179e9cff4a5@spamtrap.tnetconsulting.net>
Message-ID: <20180709052333.GB29373@thunk.org>

On Sun, Jul 08, 2018 at 09:25:27PM -0600, Grant Taylor via COFF wrote:
> 
> Please forgive my assumption and ignorance.  What OS ran on the PDP-8/i or
> PDP-15/30?

There were multiple OS's for the PDP-8 and PDP-15.  What I used on the
PDP-8/i was the 4k disk monitoring system, so named becasue it only
required 4k of 12-bit wide core memory.  The resident portion of the
OS only required 128 12-bit words, loaded at octal 7600, at the top of
the 4k memory.  It could be bootstrapped by toggling in 4 (12-bit
wide) instructions into the front console which had about 24 binary
switches[1].

[1] https://www.youtube.com/watch?v=yUZrn7qTGcs

The OS was distributed on paper tape, which was loaded by toggling in
18 instructions of the RIM loader, which was then to load the BIN
loader from paper tape into core memory.  The RIM loader was designed
to be simple and easy to toggle into the console.  (ROM?  EPROM?  We
don't need no stink'in firmware in read-only memories!)  The BIN
loader could read in a more effoiciently packed data stored in punched
paper tape.  The BIN loader would then be used to load the disk
builder program which would install the OS into the DF-32 (which
stored 32k 12-bit words on a 12" platter).

Later PDP-8's would run more a sophisticated OS, such as OS/8, which
had a "Concise Command Language" (CCL) that was designed to be similar
to the TOPS-10 system running on the PDP-10.  OS/8 was a single-user
system, though; no time-sharing!


The PDP-15/30 that I used had a paper tape reader and four DECtape
units.  It ran a background-foreground monitor.  The background system
was what was used for normal program development.  The foreground job
had unconditional priority over the background job and was used for
jobs such as real-time data acquisition.  When the
background/foreground OS was started, initially only the foreground
teletype was active.  If you didn't have any foreground job to
execute, you'd start the "idle" program, which once started, would
then cause the background teletype to come alive and print a command
prompt.  So it was a tad bit more sophisticated than the 4k disk
monitor system.

> Will you please elaborate on what you mean by "editor scripts"?  That's a
> term that I'm not familiar with.  —  I didn't see an answer to this
> question, so I'm asking again.

There have been times when I'll do something like this in a shell
script:

#!/bin/sh

for i in file1 file2 file3 ; do
   ed $i << EOF
/^$/
n
s/^Obama/Trump/
w
q
EOF
done

This is a toy example, but hopefully it gets the point across.  There
are times when you don't want to use a stream editor, but instead want
to send a series of editor commands to an editor like /bin/ed.  I
suspect that younger folks would probably use something else, perhaps
perl, instead.

					- Ted