On Sun, 03 Feb 2019 13:03:16 -0500, Dennis Lee Bieber wrote:

>  Xerox Sigma-6... Relatively fat machine for the mid-70s
> (four-bank/four-port, interleaved) 512kB (though I could swear ours was
> somehow doubled to 1Mb*). On a good day we'd often have between 40 and
> 60 terminals active, along with the batch queue (we actually had a
> Honeywell Level-6 being used as a terminal server, replacing racks of
> Gandalf equipment https://en.wikipedia.org/wiki/Gandalf_Technologies )
>
Different era - I was using the Elliott in 1967/68

>  Pretty sure we had 6 100MB drives, and it was a big thing when we
> obtained a 300MB drive to be used for swap space.
>
Same again - the 1903S was released in 1971 and was a medium scale
machine - and ours was a fairly small example.

>  The chip could access 1MB, but probably used some of that for
memory
> mapped I/O (rather than using the separate I/O port/control that Intel
> chips supported).
>
Sure, but you couldn't physically fit that much RAM into an IBM PC-AT or
PC-XT

Around 1980 I was working at the BBC, this time on ICL 2966 systems. The
production system was normally running 11 or 12 different online systems
that together supported around 400 green-screen 24x80 terminals. This
mainframe had 16MB of RAM. The development system also served as backup
for the live system and had even less RAM - 8MB - I never knew how many
developers it supported, but we were all using it interactively, writing
interactive systems in COBOL the used IDMSX databases.

Not that any of the above is relevant to my point - which is that before
multi-colour graphical displays became the norm, personal computers and
mainframes running typical back-office systems could and did routinely
use what now look like laughably small amounts of memory.


--
Martin    | martin at
Gregorie  | gregorie dot org

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