A·30
HP 9895A Disc Memory
Command
Set
HP-IB CRC
Secondary
Type:
Control.
Purpose:
Description:
The HP-IB CRC secondary is part of the 9895A command
set to
be
compatible with future HP-IB devices which use
the CRC data tests of the future HP-IB control chips. The
9895A
will
ignore this command; that
is,
not set
1/
0 prog-
ram error when it is received.
The 9895A can
be
addressed to talk or listen.
If
addressed
to listen, any
number
of data bytes may
be
sent;
if
addres-
sed to talk,
an
EOI
will
be
sent over the HP-IB.
HP-IB Sequence:
Parallel Poll:
Door
Lock
Type:
Purpose:
Description:
ATN
rxx~DDRSI
Pnmary
Talk
or
Listen
ATN
PI110111
I
Secondary
I
P
p
E
The parallel poll response
is
re-enabled after the operation
is
completed, normally
or
abnormally.
Control.
This
command
will lock
the
disc
access
door
on
the
selected drive.
NOTE
Normal
operation
of
the
9895A will
lock
the
access
door
whenever a drive
is
selected for
an
operation.
When the door
is
locked, the
heads
are
also loaded. The heads
loaded
position represents the maximum wear condition for the
disc.
After sending the secondary, the
opcode
and
the unit
number, the 9895A
will
issue a command to the selected
drive to lock the door. The door
will
remain locked
and
the
heads loaded until
one
of the following conditions occur:
1.
A Door Unlock command,
2. A Clear command,
3.
An
Initiate Self-Test command.
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