[TUHS] core

Arthur Krewat krewat at kilonet.net
Sun Jun 17 08:38:47 AEST 2018


On 6/16/2018 6:14 PM, Johnny Billquist wrote:
> I believe the KS-10 made use of that, though.

Absolutely.

The 36-bit transfer mode requires one memory cycle
(rather than two) for each word transferred. In 36-bit
mode, the PDP-11 word count must be even (an odd word count
would hang the UBA) . Only one device on each UBA can do
36-bit transfers; this is because the UBA has only one
buffer to hold the left 18 bits, while the right 18 bits
come across the UNIBUS. On the 2020 system, the disk is the
only device using the 36-bit transfer mode.



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