Page 221 - Accounting Information Systems

192 PART II Transaction Cycles and Business Processes

Appendix

Batch Processing Using Sequential

Files

igure 4-22 illustrates a legacy sales order system that uses batch processing and sequential files.
Because this system uses the sequential file structure for its accounting records, either tapes or
F disks may be employed as the physical storage medium. For day-to-day operations, however, tapes
are inefficient because someone must mount them on a tape drive and then dismount the tape when the
job ends. This approach is labor-intensive and expensive. The constant decline in the per-unit cost of disk
storage in recent years has destroyed the economic advantage of using tapes. Typically, an organization
using sequential files will now employ disk storage devices. The operational features of sequential files
are the same for both tape and disk media, but the disk storage devices can be left online for ease of
access, requiring no human intervention. Today, tapes are used primarily as backup devices and for stor-
ing archive data. For these purposes, they are an efficient and effective storage medium.
The computer processing phases of a batch system with sequential files was discussed in detail in
the Appendix to Chapter 2. The main points of that discussion are briefly reviewed in the following
paragraphs.

Keystroke

The process begins with the arrival of batches of shipping notices from the shipping department. These
documents are copies of the sales orders that contain accurate information about the number of units
shipped and information about the carrier. The keystroke clerk converts the shipping notices to magnetic
media to produce a transaction file of sales orders. This is a continuous process. Several times throughout
the day, the keystroke clerk receives and converts batches of shipping notices. The resulting transaction
file will thus contain many separate batches of sales orders. Batch control totals are calculated for each
batch on the file.

Edit Run

Periodically, the batch sales order system is executed. In our example, we will assume that this occurs at
the end of each business day. The edit program is the first run in the batch process. This program vali-
dates transactions by testing each record for the existence of clerical or logical errors. Typical tests
include field checks, limit tests, range tests, and (price quantity) extensions. Recall from Chapter 2 that
detected errors are removed from the batch and copied to a separate error file. Later, these are corrected
by an authorized person and resubmitted for processing with the next day’s business. The edit program
recalculates the batch control totals to reflect changes due to the removal of error records. The clean trans-
action file is then passed to the next run in the process.