>< used in the 7000-series computers to SLT (hybrid integrated circuits on
>< ceramic substrates, first used in System/360 in 1964).
> Yep.
> I disagree that a 286 had more raw cpu performance than some of the big
> transistor machines. I still remember the BOCES/LIRICS KA10 running some
> 300 users. I've never seen a 286 run more than 4. Same applies to IBM
> 2060s.
It's a thruput problem - if the main CPU has to handle every
byte in and out, you're just doomed. Just about calculating
(Additions per second etc.) a 286 can catch up. It's more
about the I/O concepts and devices. Add a versitale IOC and
blockmode operations and you could run dozends of users on
a 286. Even when using a clumbsy unix like byte orientated
OS. And wehn using applications, specialy designed to be
aware and operate in blockmode even a hunded might be possible.
Ten years ago I designed a small 286 system to act as a
terminal/dial up server running a stand alone aplication
and accesing a database/transactionsystem running under
SIEMENS BS2000 (an /390 compatible system) - in a testrun
we had up to 64 users with an accestime below 1s per full
screen, with up to 12 concourent requests, even including
the mainframe transaction (needed in about 70% of all
requests). And still only a CPU usage of less than 20%
on a 6 MHz 80286!
To be honest, this system had a little helper - all serial
I/O has been handled by an I/O subsystem with one Z80 for
each two ports - only if a reciving transmission was completed
the 286 had to act - and for sending only the data had to
be transmited to the Z80 memory window via DMA.
The host connection was based on a 230 kbit serial line
also operating in a kind of blockmode, using a HDLC like
multiplex protocoll.
The neat thing was that the OS was just linear and message
driven - no real time and no preemptive multitasking.
Everything was just so fast that a cooperative sheme did
work out quite well.
So don't underestimate the power of a micoprocessor. We
just bring them unde a yoke, no 'real' processor ever
har to carry.
Gruss
H.
--
Ich denke, also bin ich, also gut
HRK
Received on Mon Oct 19 1998 - 09:03:16 BST