Interrupt
at
Channel
End
(Bit Position 35).
An
I/O
interrupt
may
be
requested when the
device
signals a "channel
end"
(signifying
that
the
current
order has been
either
com-
pleted
or
terminated) by coding the Interrupt
at
Channel
End
(ICE) flag as a
1.
If the
I/O
interrupt level within the
interrupt
system (location XISC') is armed,
enabled,
and
not
inhibited,
the request will
be
processed by the
BP
in
ac-
cordance
with the priority
that
prevai
Is
within the interrupt
system, the
lOPs, and the
I/O
subchannels
of
the MIOP.
The
occurrence
of
an
I/O
interrupt
because
of
a
"channel
end
ll
is reported as status information (bit position
11
of
register
R)
when the
BP
executes
an
AIO instruction (nor-
mally
part
of
the
I/O
interrupt-handling
routine).
The
I/O
interrupt
request may
be
processed without affecting the
I/O
operation.
(Note:
Specific
conditions under which a
IIchannel end
ll
signal may be
generated
are
dependent
upon
the
characteri
sti cs
of
the devi
ce.
Refer to an appropri
ate
Xerox peripheral
reference
manual for further detai
Is.
)
Halt
on Transmission Error Flag (Bit Position 36).
The
fol-
lowing errors (or "unusual
end"
condition) may be
detected
by the MIOP when
an
lOCO
is being
executed:
1.
Bus
check
fault
(BCF)
whi
Ie
fetching
data.
2. Transmission Data Error
(TDE);
may also be
detected
by
device
controller.
3.
Transmission Memory Error
(TME).
4.
Write Lock Violation
(WLV),
during
input
operations
only.
5.
Incorrect length,
conditional;
see "Suppress Incorrect
Length
Flag".
6.
Memory Interface Error
(MIERR)
whi
Ie
fetching
data.
If
the
HTE
flag is coded as a 0, the above errors
are
recorded
when
detected
and reported as status information when the
BP
executed
an
SIO,
TIO, or HIO instruction, but the
I/o
operation
is not
halted.
If
the
HTE
flag
is
coded as a 1, and
any
error
(as
listed
above)
is
detected,
the
I/o
operation
is
terminated
im-
mediately.
The
error is also reported as status information
when
the
BP
executes
an
SIO,
HIO,
or TIO instruction.
The
HTE
flag must
be
coded
identically
in every lOCO
as-
sociated
with the same logical record. Thus,
if
data
chain-
ing is
specified,
the
HTE
flag in
the
new
lOCO
must
be
the
same as the
HTE
flag in the previous
lOCO.
This
restriction
applies
to
data
chaining
only,
and not to command
chaining.
In
addition
to the "unusual end" conditions listed
above,
which
may terminate the
I/O
operation
only
if
the
HTE
flag is
coded
as a
1,
any
of
the following "unusual
end"
conditions
wi
II unconditionally terminate the
I/O
operation:
1. Memory Address Error (MAE).
2.
lOP
Control Error (IOPCE).
128
Input/Output
Processor (lOP) Fundamentals
3.
Control
Check
Error (CCF).
4.
lOP
Memory Error (IOPME).
5.
Bus
Check
Fault
(BCF)
whi
Ie
fetching an
10CD.
6.
Memory
interface
Error
(MIE)
while
fetching
an
lOCO.
Interrupt on Unusual
End
Flag (Bit Position 37).
If
an
I/O
Interrupt is to be requested when an "unusual end" condition
is
detected
whi
Ie
either
fetching
or
executing
an
10CD,
the
Interrupt on Unusual
End
(IUE)
flag must be coded as
a
1.
If the
I/O
interrupt level within the interrupt system
(location
X
I
5C')
is armed,
enabled,
and
not
inhibited,
the
re-
quest
wi
II
be processed by the
BP
in
accordance
wi
th the
priority
that
prevalis within the interrupt system, the lOPs,
and the
I/O
subchannels within an MIOP.
The
occurrence
of
an
I/O
interrupt because
of
an "unusual
end"
condition
is reported as status information (bit position
12
of
reg-
ister
R)
when the
BP
executes
an
AIO instruction (normally
part
of
an
I/O
interrupt-handling
routine).
The
I/O
inter-
rupt request may be processed
wi
thout affecti
ng
the
progress
of
the
I/O
operation.
If the
IUE
flag is coded as a 0, an "unusual
end"
condition
may be
detected
but
no
interrupt
wi"
be requested.
Suppress Incorrect Length Flag (Bit
Position 38).
An
incor-
rect
length condition may
occur
when the specified
byte
count
is not equal to a fixed or prescribed byte count for a
record (e.
g.,
attempting to read more than 80 columns
of
data
from a punched card).
Specific
conditions under which
an
incorrect
length signal
is
generated
are
dependent
upon
the
device.
Refer to an appropriate Xerox peripheral
equip-
ment reference manua I for further
detai
Is.
If the Suppress Incorrect Length
(SIL)
flag is coded as a 0
when an
incorrect
length condition
is
detected,
it
is
re-
ported as an
incorrect
length and, depending upon the
de-
vice,
may be reported as an "unusual
end".
If
the
HTE
flag
is aiso coded as a
I,
the
I/O
operation is terminated and
reported as an "unusual
end".
If the
SIL
flag is coded as a 1 when an
incorrect
length
con-
dition is
detected,
it
is reported as an
incorrect
length but
suppressed as
an
"unusual
end".
Hence, the
I/o
operation
is
not
terminated.
The
presence or absence
of
an
incorrect
length condition
is reported as status information when the
BP
executes
an
SIO,
HIO,
AIO,
or TIO instruction.
Skip Flag (Bit
Position 39). If the Skip
(S)
flag is coded as
a
0,
it
has no
effect
upon the
I/o
operation.
If the
S flag is coded as a
1,
the
lOP
is
inhibited
from
ac-
cessing main memory and consequently no
data
is
transferred
between the main memory and the
data
buffers
of
the
I/O
subchanne
I.
All
other
operations or functions within the
To Next Page
Loading...
Need help?
General
