| Alto_Interfaces_Nov78.pdf | | XEROX
PALO ALTO RESEARCH CENTER
Computer Science Laboratory
April, 1973 - CSL Archieve # 3AL-038
retyped November 7, 1978
To: Alto Group
From: C. Thacker
Subject: Alto Interfaces
This memo is in response to the request for a description of the Alto I/O system. Familiarity
with the Alto is assumed 1 . .
There are two basic ways in which I/O devices may be connected to the Alto. A device may
appear to a program as one or more memory locations in the range 177000-177777, in which
case it responds to addresses from MAR, for its selection, and transfers data on the memory
data bus, MD(00)'-MD(15)'. Alternatively, a device may connect directly to the processor bus,
and be selected by task-specific F1 or F2 signals. The latter interface will usually |
