AIS Chapter 13 Input Processing Output

Input Controls (Processing Integrity)

Companies must establish control procedures to ensure that all source documents are authorized, accurate, complete, properly accounted for, and entered into the system or sent to their intended destination in a timely manner.

• Turnaround document (Form Design)

a record of company data sent to an external party and then returned by the external party for subsequent input to the system

• Field check (Data Entry Control)

an edit check that tests whether the characters in a field are of the correct field type

• Sign check (Data Entry Control)

an edit check that verifies that the data in a field have the appropriate arithmetic sign

• Limit check (Data Entry Control)

an edit check that tests a numerical amount against a fixed value

• Range check (Data Entry Control)

an edit check that tests whether a data item falls within predetermined upper and lower limits

• Size check (Data Entry Control)

an edit check that ensures the input data will fit into the assigned field

• Completeness check (Data Entry Control)

an edit check that verifies that all data required have been entered

• Validity check (Data Entry Control)

an edit test that compares the ID code or account number in transaction data with similar data in the master file to verify that the account exists

• Reasonableness test (Data Entry Control)

an edit check of the logical correctness of relationships among data items

• Check digit (Data Entry Control)

ID numbers can contain an check digit computed from other digits

• Check digit verification (Data Entry Control)

recalculating a check digit to verify that a data entry error has not been made

• Sequence check (Data Entry Control)

an edit check that determines if a batch of input data is in the proper numerical or alphabetical sequence

• Batch totals (Data Entry Control)

the sum of a numerical item for a batch of documents, calculated prior to processing the batch, when the data are entered, and subsequently compared with computer-generated totals after each processing step to verify that the data was processed correctly

• Financial total (Data Entry Control)

a type of batch total that equals the sum of a field that contains monetary values

• Hash total (Data Entry Control)

a type of batch total generated by summing values for a field that would not usually be totaled

• Record count (Data Entry Control)

a type of batch total that equals the number of records processed at a given time

• Closed-loop verification (Online Data Entry Control)

an input validation method that uses data entered into the system to retrieve and display other related information so that the data entry person can verify the accuracy of the input data

• Prompting (Online Data Entry Control)

an online data entry completeness check that requests each required item of input data and then waits for an acceptable response before requesting the next required item

Processing controls

• Header record (Processing Control)

typer of internal label that appears at the beginning of each file and contains the file name, expiration date, and other file identification information

• Trailer record (Processing Control)

type of internal label that appears at the end of a file; in transaction files, the trailer record contains the batch totals calculated during input

• Transposition error (Processing Control)

an error that results when numbers in two adjacent columns are inadvertently exchanged (46, 64)

• Cross-footing balance test (Processing Control)

a processing control which verifies accuracy by comparing two alternative ways of calculating the same total

• Zero-balance test (Processing Control)

a processing control that verifies that the balance of a control account equals zero after all entries to it have been made

• Concurrent update controls (Processing Control)

controls that lock out users to protect individual records from errors that could occur if multiple users attempted to update the same record simultaneously

• Checksum (Output Control)

a data transmission control that uses a hash of a file to verify accuracy

• Parity bit (Output Control)

an extra bit added to every character; used to check transmission accuracy

• Parity checking (Output Control)

a data transmission control in which the receiving device recalculates the parity bit to verify accuracy of transmitted data

• Fault tolerance (Availability)

the capability of a system to continue performing when there is a hardware failure

• Redundant arrays of independent drives (RAID)

(Availability)

a fault tolerance technique that records data on multiple disk drives instead of just one to reduce the risk of data loss

• Uninterruptible power supply (UPS) (Availability)

an alternative power supply device that protects against the loss of power and fluctuations in the power level by using battery power to enable the system to operate long enough to back up critical data and safely shut down

• Backup (Availability)

a copy of a database, file, or software program

• Recovery point objective (RPO) (Availability)

the amount of data the organization is willing to reenter or potentially lose

• Recovery time objective (RTO)

(Availability)

the maximum tolerable time to restore an organization's information system following a disaster, representing the length of time that the organization is willing to attempt to function without its information system.

• Real time mirroring (Availability)

maintaining complete copies of a database at two separate data centers and updating both copies in real-time as each transaction occurs

• Full backup (Availability)

exact copy of an entire database

• Incremental backup (Availability)

a type of partial backup that involves copying only the data items that have changed since the last partial backup. This produces a set of incremental backup files, each containing the results of one day's transactions.

• Differential backup (Availability)

a type of partial backup that involves copying all changes made since the last full backup. Thus, each new differential backup file contains the cumulative effects of all activity snce the last full backup.

• Archive (Availability)

a copy of a database, master file, or software that is retained indefinitely as a historical record, usually to satisfy legal and regulatory requirements

• Disaster recovery plan (DRP) (Availability)

a plan to restore an organization's IT capability in the even that its data center is destroyed

• Cold site (Availability)

a disaster recovery option that relies on access to an alternative facility that is prewired for necessary telephone and internet access, but does not contain any computing equipment.

• Hot site(Availability)

a disaster recovery option that relies on access to a completely operational alternative data center that is not only prewired but also contains all necessary hardware and software

• Business continuity plan (BCP) (Availability)

a plan that specifies how to resume not only IT operations but all business process in the event of a major calamity.

• Deduplication (Availability)

ses hashing to identify and back up only those portions of a file or database that have been updated since the last backup. Each chunk is hashed, and the chunk’s hash value is compared to the hash values of all chunks in the hash file from the previous backup.