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Laurel Message

From: SPG Date: 26 JUL 1979 0903-PDT

Subject: Change to lOP Module

To: Fairbairn

XEROX
\Ve have incQrporated the following change into the lOP ~Iodule as a
result of investigation into Keyboard-Mouse sampling. The problem
uncovered was that the 8748 in the Keyboard was expecting the Tl
input(Start Transmission') to stay low until the 8748 could respond to
the request to send data. Since this signal was driven by the
UART on the lOP, it would normally only be active for one bit time
(the Start bit) of a character containing zeroes. This would only
be about 16 microseconds every 33milliseconds. The 8748 only looks
-:.t t-hn -linn -:>h.1"\11t nnl"o nun-rtl 'lJ\{) TYlir-rnenr-Anrte en TYI~n" r&>1"111&>('tc to
""" U.I.'- J.J..I.J."" UVV"",... V..\.J.....,...., ,.., l' ".I. J JVV .1..1..1.1.,,'" V"''''''''',-,.I..I.'-6-U r...J'''' .