I plead with the programming gurus in the forum to help me in designing a program for this problem:
A local phone company is developing a coin operated telephone boxes for public use, and will include each installation a small VDU screen which will be used to inform users how to operate the telephone and to respond for the call. This time will then operate on a count down basis to indicate the time remaining for the call and will disconnect calls when the time has expired. Telephone calls are to be charged as follows:
Local calls: 10p for 20 seconds
Trunk calls: 10p for 10 seconds
International: 10p for 4 seconds
The program when executed, shall remain in a wait state until RETURN is pressed from the keyboard.
On depression of RETURN the program will request entry of the type of call required indicating; Local, Trunk, or International. This is to be entered as 'L', 'T' or 'I'. This entry must be validated.
When the user has indicated the type of call required the program shall respond with a request for coin entry; such as
"Please insert your coins now..."
There must, at this time, be a screen display which indicates the charges for the type of call requested such as
"You have requested a local call"
"The charge for this type of call is
"10p per 20 seconds"
This shall enable the users to determine what coins to enter to purchase the time they are likely to require. Coins shall be entered by typing in the value of the coins. Only the following coin figures shal be valid entries: 5, 10, 20, 50, 100.
Entry shall be indicated on screen together with the cumulative entry. Coin insertions shall be terminated by thenetry of the value zero. These entries must be validated.
On entry of the zero value coin, the screen shall clear and a new screen shall appear which requests the number to be dialed. The number to be dialed is enterd as a string. Depression of the RETURN key shall terminate number entry and at this stage the screen must clear and indicate the number dialed together with the message:
After a short pause the message shall be changed to:
"Connected - Please start your conversation"
Immediately following the 'connected...' message, a display of the time remaining must appear on the bottom right of the screen. This must be a count down of the remaining time.
When the count down time equals zero a final message must appear informing users that their time is up.