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From: Tim Bradshaw <tfb@tfeb.org>
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Date: Thu, 21 Jun 2018 00:53:52 +0100
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References: <201806202011.w5KKBOT5040344@tahoe.cs.Dartmouth.EDU>
To: Doug McIlroy <doug@cs.dartmouth.edu>
Subject: Re: [TUHS] core
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Making tube (valve) machines reliable was something originally sorted out by=
 Tommy Flowers, who understood, and convinced people with some difficulty I t=
hink, that you could make a machine with one or two thousand valves (1,600 f=
or Mk 1, 2,400 for Mk 2) reliable enough to use, and then produced ten or el=
even Colossi from 1943 on which were used to great effect in.  So by the tim=
e of Whirlwind it was presumably well-understood that this was possible.

(This is not meant to detract from what Whirlwind did in any way.)

> On 20 Jun 2018, at 21:11, Doug McIlroy <doug@cs.dartmouth.edu> wrote:
>=20
> If you extrapolate the rate of replacement of vacuum tubes in a 5-tube
> radio to a 5000-tube computer (say nothing of the 50,000-tube machines
> for which Whirlwind served as a prototype), computing looks like a
> crap shoot. In fact, thanks to the maintenance protocol, Whirlwind
> computed reliably--a sine qua non for the nascent industry.