Specifications
Status
Bits
13=1
14=1
15=1
Status
Unit 0/1
Data
available
ADT
mode
Description
1 =
Unit 1 selected,
o = Unit 0 selected
Data available from read or echo
operation
Auto data transfer
mode
selected
183~-1/2/3
Storage
Module
Drive
and
1867
Drive
Unit
In
this section,
CU
is
the control unit and
DMA
is the direct
memory access bus.
Status
Bits
0=1
1=1
2=1
3=1
4=1
5=1
6=1
Status
Busy
Interrupt
CU
selected
Transfer
complete
Alarm
Seek
complete
End
of
cylinder
Description
The drive interface or control
unit is
busy
with the previous
operation (read, write, function,
seek, or poll).
It
is cleared
by
operation completion, abort, or
clear function.
The interrupt is active. Bits
2,
3,
4,
5,
6,
and 7 indicate the
cause· of the interrupt.
The control unit
is
selected
by
this drive interface.
The read or write operation is
completed.
The drive interface detected lost
direct memory access data,
forced disconnect condition,
memory address error, direct
memory access parity error, pro-
tect
fault, or control unit error.
One
or more drives completed
seek operations. The
CPU
should
poll the drive interface to find
the drives concerned.
The read or
write reached a
cylinder boundary. Data
on
the
current cylinder
may
be trans-
ferred, however. A
new
seek
com
mand and disk addresses
must
be
supplied for data
on
the
next cylinder.
7=1
Alternate The drive interface
was
inter-
drive interface rupted
by
the other drive
interrupt interface
in
a dual
CPU
configu-
ration.
Status
Bits
8=1
9=1
10=1
11=1
12=1
13=1
14=1
15=1
Status
Protected
Lost data
on
DMA
Forced
disconnect
Description
The protect jumper is installed;
the disk system is operating in
the protected mode.
The transfer
rate
of communica-
tions adapter and drive exceeded
the direct memory access ability
to
handle the data. The read or
write operation
was
terminated.
The alternate channel executed a
forced release function. The
drive interface disconnects from
the control unit, and the
alter-
nate channel gains control. The
operation
in
progress terminates
at
the end of the current sector.
Memory
The
drive interface attempted
to
address error address a nonexistent location in
the
CPU
main memory. The
operation
in
progress terminates
at
the end of the current sector.
D~A
Parity Parity error
on
direct memory
error access; the operation terminates
at
end of the current sector.
Protect error
An
unprotected drive interface
operation attempted to write
data into the protected
CPU
memory. The
CPU
inhibits the
write and the operation termi-
nates
at
the end of the current
sector.
CU
error The drive interface detected an
error
in
the control unit opera-
tion. The
CPU
must read the
drive interface and/or control
unit status to determine the
error.
Address field
The drive is operating
in
the
sector address field.
The storage module drive also has a variety of other status
information available. The other status words are obtained
by
sending the normal
WES
code during
an
input command
with the D value specifying the status type requested.
Table 6-1 summarizes the status types. For a standard
CYBER
18-20 or 18-30 Timeshare Computer System with
one storage module drive,
WESD
is
070x
16
when
x = D
in
range 0 through F
16
•
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