I believe tht the reliability problem with the 701
was not hard tube failures, but transient errors
in the Williams tube memories. This problem was
corrected when IBM transitioned to core memory.
--Bill
--- William Donzelli <aw288_at_osfn.org> wrote:
> > I was reading that 1961 BRL survey, and found the
> user reports
> > of the IBM 701 fascinating. They apparently had an
> average
> > uptime of about 2-4 hours. That doesn't seem like
> much by
> > today's standards, but then how often does Windows
> crash on you?
>
> One of the often told stories of the early days of
> computers is that of
> the completely unreasonable downtime, due to tube
> failure. There is even a
> myth (pretty much disproved) about AN/FSQ-7 SAGE
> techs wearing roller
> skates to replace the constantly dying tubes.
>
> Basically, tube computers were not that bad, all of
> the time. The use of
> "average" is being distorted here. When a 701 or 650
> or whatever was
> placed into service, you could expect tubes to die
> out (rarely from
> "burnout" - loss of emission was the main culprit)
> at an alarming
> rate. One every two hours is probably not
> unreasonable, as the marginal
> tubes in their infancy are weeded out. Once these
> tubes were gone - I have
> heard this could be six months - tube computers were
> quite reliable. Often
> whn an old IBM or Burroughs module is unearthed, a
> quick look at the
> datecodes on the tubes will reveal that most are
> probably originals to the
> machine.
>
> William Donzelli
> aw288_at_osfn.org
>
>
>
Received on Thu Oct 28 2004 - 19:08:49 BST