Xerox Alto I User Manual

Alto Hardware Manual
llB
F2 VALUE
lOB
llB
12B
l3B
14B
15B
16B
BS VALUE
3
4
STROBE
NAME
INIT
RWC
RECNO
XFRDAT
SWRNRDY
NFER
STROBON
NAME
"KSTAT
"KDATA
Section 6: Disk and Controller
48
Initiates a disk seek operation. The KDATA register must have
been loaded previously, and the
SENDADR bit of the KCOMM
register previously set to 1.
EFFECT
NEXT
.. NEXT OR (if WDTASKACT AND WDINIT) then 37B else 0)
NEXT" NEXT OR (if current record to be written then 3 elseif
current record to be checked then 2 else 0)
NEXT"NEXT OR MAP (current record number) where
MAP(O) = 0
MAP(l) = 2
MAP(2) = 3
MAP(3)
= 1
NEXT"NEXT OR (if current command wants data transfer then 1
else 0)
NEXT"NEXT OR (if disk not ready to accept command then 1 else
0)
NEXT"NEXT OR (if fatal error in latches then 0 else 1).
NEXT"NEXT OR (if seek strobe still on then 1 else 0).
EFFECT
The KSTAT register is placed on BUS. It has the format of a disk
status word.
The disk
mput data register is placed on BUS.
A feature of interest mostly to the diagnostic microcode writer is that if one reads the disk input data
register
while writing, what should appear is delayed written data correctly aligned on word boundaries.
This
is a painless way of checking most of the data paths in the disk controller hardware.

Xerox Alto I Specifications

General

Brand	Xerox
Model	Alto I
Category	Desktop
Language	English