1. Commercial Data Processing
Lesson 4:
CDP Cycle: Processing, Storage & Output

2. By the end of this lesson you will be able to:
interactive processing
batch processing
sequential access
direct access
types of output for a CDP process
multi-user database (credit).

3. The Data Processing Cycle
Data is collected on a source document (which may be a turnaround document).
data collection & preparation
Data is entered into the computer for processing.
Automatic data entry reduces the mistakes made by people and makes this inputting quicker.
data input
Data is processed either: interactively or in a batch.
Processed data is stored to backing store.
data processing & storage
Processed data is either: displayed on a monitor, printed onto paper (often as a turnaround document) or output to a file.
output of data

4. Processing of CDP Data Interactive Processing
Data input into a CDP process will be processed either using:
Interactive Processing or
Batch Processing.
Interactive Processing
Interactive processing processes a transaction data immediately.
Interactive processing needs instant access to the mainframes processing power.
Interactive processing is used for tasks that cannot wait eg ATMs, Flight Check-in, Train tickets.

5. Batch Processing
Batch processing is used when a large amount of data is collected into a large transactions file (batch).
The batch is processed at a later time.
Batch processing can only be used for tasks that don’t require an immediate response eg payrolls and updating bank accounts.
Batch processing is used to reduce demand on the mainframe’s processing power at peak times.

7. Storing of CDP Data Data must be stored to backing store.
The backing storage used depends on the type of processing to be used and the purpose of the storage.
Backing storage devices are classified into:
Type of Access
Medium
Processing
Sequential Access
Data stored on tape eg magnetic tape.
Batch File
Random Access
Data stored on disc eg hard disc.
Interactive

8. Type Of Access Sequential Direct (Immediate) Method Problems Uses
Data is stored one item after another.
Each record has be read in the order in which it was stored.
Data is stored where ever the device decides.
The device keeps a storage allocation table so that data is retrieved instantly.
Problems
It is time consuming to find a particular file.
Devices are usually more expensive than tape.
Uses
Backing-up files
Save data for batch processing.
Data for interactive processing.
Backing-up files.
Not suitable for tasks requiring:
immediate access.
lots of data being read.

10. Output from CDP Data output from a CDP processed can be: 1. Paper
Bills and statements will be printed so that they can be sent to customers.
Printing by the CDP process tends to be on pre-printed stationery. Pre-printed stationery is paper has had the expensive coloured features printed on by a specialist company. Pre-printed stationery is used to make printing from the CDP process faster and cheaper.
2. Screen
Information can be output and sent via the internet so that customers can look at their bills/statement on their monitor.
This method saves money – print onto paper and no need to post. It also allows the customer to look at the information when convenient.
File
Output can be saved to backing store for use later.

11. Multi-user Databases
A multi-user database is a database that can be accessed by many users at the same time. Companies will store their product catalogue, sales records, etc so that more than one member of staff can be updating records at the same time.
Multi-user access is possible because the file is held on a central computer either a mainframe or a file server.
Multi-user databases need to be able to:
Allow many users to look at the data at the same time, but
Prevent the same record being altered by 2 users at the same time
Lock out prevents 2 users changing one record at the same time.

12. Answer the following questions in your jotter.
Explain the term interactive processing.
Explain the term batch processing.
Suggest the most suitable type of processing:
Cash withdrawal from an ATM.
Totalling cost of shopping basket.
Processing a companies monthly payroll.
Customer booking a holiday.
Explain the term sequential access backing store.
Explain the term direct access backing store.
Suggest the most suitable type of backing store the transactions in question 3.
Suggest a suitable output method for payroll programs.
Why might a customer preferred to be ed their bank statement?
Explain why companies used multi-user databases (credit).
Explain why multi-user database must have a lock out system (credit).