VAXen and minimal memory (was Re: The PDP11/04 has landed..)

Huw Davies huw.davies at
Fri Feb 12 07:25:53 CST 2016

> On 12 Feb 2016, at 06:48, Rich Alderson <RichA at> wrote:
> DEC was the first company to build timeshared large systems as standard[1],
> beginning with the PDP-6.  The PDP-10 (a reimplementation of the PDP-6) was
> successful enough to go through 3 generations (renamed to DECsystem-10 and
> DECSYSTEM-20) of market success, enough to inspire 2 research labs (Xerox
> PARC and Stanford Artificial Intelligence Laboratory) and 3 manufacturers
> (Foonly, Systems Concepts, and XKL) to design and, except for SAIL[2], to
> build clones.  The PDP-6 came out in 1964, the PDP-10 in 1967 (KA-10), with
> later members of the family in 1971 (KI-10), 1974 (KL-10), and 1979 (KS-10).
> All of them were capable of handling up to 100 users.

Thanks for getting the case correct for DECsystem-10 and that other one :-)

When I started managing VAX/VMS on an 11/780 we had two RM03 disk drives and 1.25MB of memory supporting 16 users. It was really important to get more than 1MB of memory to ensure that you got the larger memory boards that would allow expansion to 2 (4?) MB.

ISTR that with educational discount our 11/780 cost about AUD$250K in 1982.

I guess I’m lucky in that I still manage OpenVMS systems today 30+ years later…

Huw Davies           | e-mail: Huw.Davies at
Melbourne            | "If soccer was meant to be played in the
Australia            | air, the sky would be painted green" 

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