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From: Arrigo Triulzi <arrigo@alchemistowl.org>
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To: Paul Winalski <paul.winalski@gmail.com>
Subject: Re: [TUHS] Old mainframe I/O speed (was: core)
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On 21 Jun 2018, at 16:00, Paul Winalski <paul.winalski@gmail.com> wrote:
[...]
> for the microcode to customers.  There were several hacks in there to
> slow down the disk I/O so that it didn't outperform the model 30.

Is this the origin of the lore on =E2=80=9Cthe IBM slowdown device=E2=80=9D?=


I seem to recall there was also some trickery at the CPU level so that you c=
ould =E2=80=9Cfield upgrade=E2=80=9D between two models by removing it but a=
) I cannot find the source and b) my Pugh book is far and cannot scan throug=
h it.

Arrigo=20