[Simh] BLISS and C

[Phil Budne]

Rich Alderson wrote:
> Ken had no tools for the PDP-7, which was part of a Graphics-1 setup (with a
> Type 340 display)

A nit, but I think the display controller was Bell designed, custom
hardware.  PDP-7 UNIX used it as a glass TTY (independent from the
console TTY).  I simulated JUST enough of it (character display,
keyboard and auto-pressing the clear screen key) in SIMH so that you
can have two users active!  I worked from BTL documents to implement
the simulation.

Since the world has changed so much since I did the original XY
display code that's now integrated into SIMH (tho I wrote it to be
simulator agnostic and stand-alone), I thought about making a Web UI
that lit the light that says "display list memory area full", and
forced the user to click on an HTML button to clear the screen!

It seemed like the majority of Graphics-1 systems built were PDP-9's
so it's possible the PDP-7 was a cast-off prototype.

Somewhere I've a description of the Graphics system being as large as
the PDP-7 itself. In addition, ISTR the disk system cost as much as
the CPU (I think the same type of disk was also used as a swap device
on KA10 timesharing systems), and fast enough to swap the high half
(4K) of memory in/out for each process painlessly.  ISTR that one or
both of the above recollections were from Doug McIlroy....

Phil