> On Apr 21, 2016, at 3:55 PM, Chuck Guzis <ccl...@sydex.com> wrote:
>
> ...
> Ten was a number that figured into various aspects. The clock was
> nomially 10 MHz;
In serial numbers 1-7 only nominally -- the clock was a ring oscillator, tuned
by tweaking wire lengths. Starting with serial number 8, there's a crystal
oscillator (in the ECS controller if ECS is present, otherwise in the CPU).
> ...
> Initially, the maximum central memory size was 131KW; late in the
> series, a 262KW option was added, necessitating extensive code changes,
I thought the 70 series (6000 series) was 131 kW max because the top bit is the
"ECS active" bit. 170 series makes it 262k.
> ...
> For a couple of years, I worked on the development a system using up to
> 4 CPUs with a common 4MW of bulk core (ECS). Since ECS transfers, after
> an initial startup overhead ran at full memory speed, a model was
> contrived that divided programs up into modules to create "chains", with
> inter-module communication, each module resident in either ECS or in a
> CPU.
Neat. PLATO made extensive use of ECS, swapping per-terminal state and
programs in and out of ECS for fast interactive service. ECS was also where
most I/O buffers went, with PPUs doing disk and terminal I/O from/to ECS rather
than central memory. A dual mainframe 6500 system (4 "unified" processors
total) did a decent job supporting 600 concurrent logged-in terminals, out of a
total of 1008 connected. That was around 1977 when I worked on that system at
the U of Illinois.
paul
