Data Processing Techniques - All about the IBM 1130 Computing ...

Section Subsections Page20 10 20 05Control techniques and devices. A list of controldevices and techniques, many of which can beincorporated into the procedure for any data processingsystem, includes:• Serial numbering. The serial numbering oforders, invoices, checks, etc., provides controlwhile the data is in transit. Each item or documentin the series or group is assigned a successivenumber; an indication of the beginning and endingnumbers accompanies the group.• Batching with a document or item count. Inbatching data with a document or an item count, theitems or documents are counted instead of numbered;an indication of the count accompanies the group.This technique can be used to control data, bothbefore and after it is punched into cards--for example,requisitions, changes, receiving reports,and punched cards for various analysis reports.• Batching with a control total. In batching witha control total, some data field that is common toall items or documents is accumulated for the controltotal, which then becomes the basis for balancingoperations during processing. The control fieldmay be an amount, a quantity, an item code, anaccount number, etc.; totals based on an accountnumber or code are known as "hash" totals. Anadvantage of this technique is that balancing canoften be performed during regular machine processingoperations at no extra cost in time.• Crossfooting. Crossfooting is the additionand/or subtraction of factors in a horizontal spreadto prove processing accuracy. It can be used on apayroll register to prove that the final totals ofnet pay and deductions equal the final total earnings;this provides control on report preparation as wellas calculating and card-punching operations. Inposting transactions to records that are temporarilystored in a computer (for example, accounts receivable),crossfooting is used to prove the accuracyof posting, either as each transaction isposted, or collectively at the end of the run, or both.• Zero balancing. Zero balancing is an effectivemethod of verification when both detail items(for example, accounts payable distribution cardsor records) and their summary (for example, anaccounts payable disbursement card or record) areprocessed together. Each detail item is accumulatedminus, and the summary plus. The result is a zerobalance if both are correct.• Negative balance test. It is possible to detecta change in sign during arithmetic operations andeither stop the machine or signal the condition forsubsequent review. In payroll applications the signcheck is used to indicate the condition in whichdeductions exceed gross pay; in accounts receivable,accounts payable, inventory, and general ledgerapplications it can be used to recognize any balancethat becomes negative.• Blank field test. This means checking anydata field for all blank positions. As a computercontrol, it can be used to prevent the destructionof existing records in storage, indicate when thelast item from a spread card has been processed,skip calculation if a rate or factor field is blank,etc.• Comparing. Comparing, as a control technique,permits data fields to be machine-checkedagainst each other to prove the accuracy of matching,merging, coding, balancing, reproducing,gang punching, and record selection.• Sequence checking. Sequence checking is usedto prove that a set of data is arranged in eitherascending or descending order before it is processed.It is generally a mechanized operation andmay be performed in a separate machine run orsimultaneously with another operation in one run.• Visual comparisons. Comparisons are basedprimarily upon experience, past performance, anda knowledge of trends that have intervened. Byknowing the status as of a certain time and observingtrends since that time, it is possible to determineto some degree whether present recordsrepresent a complete and accurate picture. Forexample, present-period payroll is often comparedagainst last-period payroll to spot any questionablevariations.Controls on processing operations. The numberof available techniques indicates the need for athorough study of your application and equipmentinorder to come up with a system of controls whichis adequate but which does not overcontrol and delayprocessing. In so doing, it is desirable to mechanizeas many controls as possible. Mechanized controlsare always performed at a constant, rapidspeed; manual ones are not. A study of the applicationwill reveal:1. How closely it is to be controlled.2. Points in the procedure at which controlsmust be placed.3. The correcting and restart procedures to beemployed at each point, in case the operation doesnot balance. If the procedure is a manual one, itshould be clearly documented for operator referenceand training purposes.4. How accounting control responsibilities areto be divided.The basis for control during processing must beestablished as data enters your installation. This