From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Subject: Re: OS-8
Date: Thu, 8 Oct 1992 14:29:15 GMT
Distribution: na
Organization: University of Iowa, Iowa City, IA, USA

From article <1992Oct7.185551.8168@pony.Ingres.COM>, by kerry@Ingres.COM (Kerry Kurasaki):
> How many other operating systems do you know where the resident portion
> was only 256 12-bit words?

I wrote a console monitor system for the DDP-516 where the resident system
was 15 words of ROM plus 6 words of dedicated peripheral interface
registers.  The DDP-516 was a 16 bit minicomputer made by Computer Control
Corporation and later by Honeywell.  My code ran on the 16K word version
of this machine (there were options to expand the memory to 64K words).

The 15 words of ROM were the bootstrap program that, when started with a
program number in the B register, would load that program from disk and
run it.

The 6 words of dedicated peripheral interface registers held the stream
pointers for standard input, standard output and standard binary.  One word
was either -1 or a disk sector address.  If it was -1, that stream was
directed to the console, otherwise, the stream was from the indicated disk
address.  The other word was the byte offset in the sector of the next byte
to be read from or written to on that stream.

I wrote a shell that used this.  The shell included the code needed to
translate program names to program numbers, it did I/O redirection for
applications run under it, and it had conditional and iterative control
structures that operated in terms of the success or failure of the programs
it ran (as indicated by termination codes left in the accumulator by those
programs).

I also wrote patches for the standard Honeywell assembler, Fortran compiler,
and linking loader to make them undestand the streams, standard input,
standard output and standard binary.  As delivered by Honeywell, these were
purely paper-tape oriented software; as previously patched, these ran to
and from dedicated disk addresses.

All this was done at the Bell Labs Accoustics Research Department (Dept
1227) between the summer of 1973 and the summer of 1974.

It's worth noting that the DDP 516 computers we had at Bell were
workstations on a LAN.  There were 3 user workstations, and a 4th DDP 516
used as a file server (it had 4 disk pack transports).  There was also a
CSP 30 compute-server on the net; this was a 1 mip machine, and it had no
I/O except the network.  The network was Pierce Loop slotted ring, one of
the very first ring networks (I know of only two other experimental token
ring networks that existed at the time).

Our DDP 516 workstations were, in retrospect, fitted out as good prototypes
of modern workstations.  Each had a graphics display (backed by two
dedicated disk tracks), a mouse, a set of knobs for analog input, a votrax
synthesizer for sound output, a high speed ADC for sound input, an
electrostatic (Versatek) printer for graphics and text output, and a
Diablo Hi Type terminal for a console terminal.  In departure from the
modern perspective, each also had a card reader, and there was a keypunch
beside each workstation.  We didn't have a text editor!

					Doug Jones
					jones@cs.uiowa.edu
Newsgroups: alt.sys.pdp8