IBM 1130 User Manual page 114

Section
Subsections Page
20 10
I
20 05
Control techniques and devices. A list of con-
trol devices and techniques, many of which can be
incorporated into the procedure for any data proc-
essing system, includes:
• Serial numbering. The serial numbering of
orders, invoices, checks, etc., provides control
while the data is in transit. Each item or document
in the series or group is assigned a successive
number; an indication of the beginning and ending
numbers accompanies the group.
• Batching with a document or item count. In
batching data with a document or an item count, the
items or documents are counted instead of numbered;
an indication of the count accompanies the group.
This technique can be used to control data, both
before and after it is punched into cards--for ex-
ample, requisitions, changes, receiving reports,
and punched cards for various analysis reports.
• Batching with a control total. In batching with
a control total, some data field that is common to
all items or documents is accumulated for the con-
trol total, which then becomes the basis for balanc-
ing operations during processing. The control field
may be an amount, a quantity, an item code, an
account number, etc.; totals based on an account
number or code are known as "hash" totals. An
advantage of this technique is that balancing can
often be performed during regular machine proc-
essing operations at no extra cost in time.
• Crossfooting. Crossfooting is the addition
and/ or subtraction of factors in a horizontal spread
to prove processing accuracy. It can be used on a
payroll register to prove that the final totals of
net pay and deductions equal the final total earnings;
this provides control on report preparation as well
as calculating and card-punching operations. In
posting transactions to records that are temporarily
stored in a computer (for example, accounts re-
ceivable), crossfooting is used to prove the accu-
racy of posting, either as each transaction is
posted, or collectively at the end of the run, or both.
• Zero balancing. Zero balancing is an effec-
tive method of verification when both detail items
(for example, accounts payable distribution cards
or records) and their summary (for example, an
accounts payable disbursement card or record) are
processed together. Each detail item is accumulated
minus, and the summary plus. The result is a zero
balance if both are correct.
• Negative balance test.
It
is possible to detect
a change in Sign during arithmetic operations and
either stop the machine or signal the condition for
subsequent review. In payroll applications the sign
check is used to indicate the condition in which
deductions exceed gross pay; in accounts receivable,
accounts payable, inventory, and general ledger
applications it can be used to recognize any balance
that becomes negative.
• Blank field test. This means checking any
data field for all blank positions. As a computer
control, it can be used to prevent the destruction
of existing records in storage, indicate when the
last item from a spread card has been processed,
skip calculation
if
a rate or factor field is blank,
etc.
• Comparing. Comparing; as a control tech-
nique, permits data fields to be machine-checked
against each other to prove the accuracy of match-
ing, merging, coding, balancing, reproducing,
gang punching, and record selection.
• Sequence checking. Sequence checking is used
to prove that a set of data is arranged in either
ascending or descending order before it is proc-
essed.
It
is generally a mechanized operation and
may be performed in a separate machine run or
simultaneously with another operation in one run.
• Visual comparisons. Comparisons are based
primarily upon experience, past performance, and
a knowledge of trends that have intervened. By
knowing the status as of a certain time and observ-
ing trends since that time, it is possible to deter-
mine to some degree whether present records
represent a complete and accurate picture. For
example, present-period payroll is often compared
against last-period payroll to spot any questionable
variations.
Controls on processing operations. The number
of available techniques indicates the need for a
thorough study of your application and equipment in
order to come up with a system of controls which
is adequate but which does not overcontrol and delay
processing. In so doing, it is desirable to mechan-
ize as many controls as possible. Mechanized con-
trols are always performed at a constant, rapid
speed; manual ones are not. A study of the appli-
cation will reveal:
1.
How closely it is to be controlled.
2. Points in the procedure at which controls
must be placed.
3. The correcting and restart procedures to be
employed at each point, in case the operation does
not balance.
If
the procedure is a manual one, it
should be clearly documented for operator refer-
ence and training purposes.
4. How accounting control responsibilities are
to be divided.
The basis for control during processing must be
established as data enters your installation. This