External And Internal Interrupts - IBM 1710 Manual

External
and
Internal Interrupts
External interrupts are interrupts that occur as the
result of conditions in the process. These interrupts
cause the 1710 to give almost immediate attention to
a situation or occurrence in the process whenever re-
quired.
Internal interrupts originate within the 1710 Con-
trol System and facilitate the concurrent handling of
many programs.
External Interrupts
A maximum of twelve external (process) interrupts are
available with the External Interrupt feature. An in-
dicator is provided for each interrupt. Once an inter-
rupt indicator is turned on by its related interrupt, it
remains on until it is interrogated by the program.
The External Interrupt indicators are assigned indi-
cator codes 48 through 59.
Internal Interrupts
Nine internal interrupts are available in groups of
three, as follows:
Basic Interrupt Feature
Operator Entry (18)
Any Check (19)
CE (Customer Engineer) Interrupt (27)
Input/Output Interrupts Feature
Multiplex Complete (40)
Seek Complete (42)
Any slOe (Serial Input/Output Channel) (45)
Timed Interrupts Feature
Analog Output Setup
One Hour
One Minute
(41 )
(44)
(43)
An indicator is provided for each interrupt listed
above, and is identified by the number in parentheses.
An interrupt condition turns on its associated indica-
tor, which remains on until program recognition occurs.
Operator Entry Interrupt (Indicator 18). The Oper-
ator Entry interrupt provides for the entry of data pre-
viously set in the seven Manual Entry switches on the
1711 Operator's Panel. When the process opera tor posi-
tions the Manual Entry switches and presses the Oper-
ator Entry key, the Operator Entry indicator turns on
and the computer branches to the program subroutine
that causes the contents of the Manual Entry switches
to be read into core storage.
26
This indicator is a basic feature of the system; its
interrupt function is available as part of the Basic
Interrupt feature.
Any Check Interrupt (Indicator 19). The Any Check
indicator (19) is turned on by any of nine error con-
ditions shown here:
Read Check Indicator 06
Write Check Indicator 07
MAR Check Indicator 08
MBR-E Check Indicator 16
MBR-O Check Indicator 17
TAS Check Indicator 21*
Function Register Check Indicator 22*
Analog Output Check Indicator 23*
Any Disk Check Indicator 39*
*These indicators are available only if their associated
special features are installed on the system.
When one of these errors occurs, the Any Check in-
terrupt is initiated and the computer can branch to the
Interrupt Identification routine (Figure 18). (Thus,
all of the indicators shown above initiate an interrupt,
through the Any Check interrupt.) This routine identi-
fies the interrupt and initiates a branch to the Any
Check Interrupt subroutine or Error Analysis subrou-
tine. The programming philosophy of this subroutine
is to keep the process in operation, regardless of errors,
if at all practical. Thus, as shown in the logic diagram
(Figure 18), each error check is tested individually
with a Branch Indicator instruction, and, if that indi-
cator is on, a one is added to the count of that indi-
vidual error. The count of each type of error can be
reviewed by the
IBM
Customer Engineer during diag-
nostic testing and analysis. Note that the
TAS
error is
handled differently if the error occurs during an An-
alog I/O operation - here, the analog instruction will
repeat until it is executed correctly or until three con-
secutive errors occur. When three consecutive
TAS
errors
occur on an analog input or output operation,
It
IS
assumed that the control system is unreliable, and
system operation is discontinued.
The Any Check indicator is a basic feature of the
system, its interrupt function is available as part of the
Basic Interrupt feature.
CE (Customer Engineer) Interrupt (Indicator 27).
The CE Interrupt provides the
IBM
Customer Engineer
with a rapid method of transferring the 1710 from
normal program operation of the process to 1710 diag-
nostic programming. For example, the CE can initiate a
routine maintenance check of the 1710 Control System
by simply depressing the CE Interrupt - the computer