1. IGCSE ICT
Stock Control

2. The syllabus says you must:
Understand the need for and use of automated stock control systems
Be able to discuss the advantages and disadvantages of automated stock
control systems
Understand the role of the check digit
as a form of validation

3. Stock control : the old way
Price labels were handwritten and stuck on manually
Staff/time/cost
Labels could be misread/changed
Yearly stock-check: closed for business

4. The problems Slow Costly Required many staff Impact on revenue
Accuracy?
Lost revenue through wrong or misread labels
Lost revenue through stock-taking closures
Stock control done by guesswork

5. The technology behind ASCS
ASCS rely on barcodes
Barcodes allow quick identification of product details when the barcode is scanned
The barcode reader scans the barcode using a laser
It retrieves the price and the
details from the database

6. What’s in a bar code?
Bar codes are made of alternating dark and light lines of varying thickness

7. What’s in a bar code?
The barcode contains data about the type of product, size, manufacturer and the country of origin. 
It also contains a check digit, so that the computer can validate that the data has been read in correctly.

8. What’s in a bar code?
The barcode does not contain price. The price is held in the database instead.
This makes it easy to change if there are special offers or prices go up. Imagine if the price was part of the barcode. Every time the price changed, you would have to replace all of the packaging.

9. What’s in a bar code?
Once the barcode has been recognized by the database and the price found, the data is sent from the central computer to the till (Electronic Point of Sale - EPOS).

10. The check digit The check digit is a form of validation
It is used to ensure no errors occurred when the barcode was read in
There are a number of ways of calculating check digits depending on how many digits there are in the barcode

11. This method works for codes with 11 digits:
Add the digits in the odd positions, multiply by 3
( = x3=48)
Add the digits in the even position: =9
Add the two together: = 57
Check digit is 3 (needs to be added to make next multiple of 10). Checked every time a bar is scanned!
even digit positions
odd digit positions

12. Where are bar codes used?
Library book systems
Administration systems (eg hospitals)
Passport & ID card systems
Equipment checking systems (eg fire extinguishers)
Automatic stock control systems

13. Sequence of events
Barcodes on all items: each is associated with a stock file holding details of price, stock level, description etc.
Customer goes to checkout: barcodes scanned
Stock file is searched, record by record, until a match is found
Appropriate record is accessed
Price & description sent to EPOS
Stock level reduced by 1: new stock level written to file

14. Sequence of events
If new stock level is = or 1 less than re-order quantity, new batch is automatically ordered
Flag assigned to item to indicate order (stops re-order being made for EVERY purchase!)
This is repeated for every item in basket/trolley
Itemized bill given to customer
Loyalty card updated/takings file updated
Barcodes on cartons of new goods used to update stock file & flags removed

15. Advantages & Disadvantages
Accuracy
Speed
Optimum stock levels
Patient safety
Equipment safety
Analysis
Automatic re-ordering
Automatic scheduling of updates etc
Disadvantages
Cost
Training
Over-reliance on technology

16. Today’s assignment:
Download the file Electronic Fund Transfer Simulation
Enter some purchases and look carefully at the following:
Banking/EFTPOS data
Stock levels
Receipt

17. Homework
Read the information at
Go to and complete the homework assignment.