Q. Illustrate Character Coded Data?

The input output happens in the form of ASCII data. These ASCII characters are entered as a string of data. For illustration to get two numbers from console we can enter numbers as:

As every digit is inputwe will store its ASCII code in a memory byte. After first number was input number will be stored as follows:

Number is entered as:

Every one of these numbers would be input as equivalent ASCII digits and required be converted either to digit string to a 16-bit binary value which can be used for computation or the ASCII digits themselves can be added that can be followed by instruction which adjust the sum to binary. Let's use conversion operation to perform these calculations here.

Another significant data format is packed decimal numbers (packed BCD). A packed BCD comprises two decimal digits per byte. Packed BCD format has subsequent advantages:

• BCD numbers permit accurate calculations for nearly any number of significant digits.
• Conversion of packed BCD numbers to ASCII (and vice versa) is relatively fast.
• An implicit decimal point can be used for keeping track of its position in a separate variable.

The instructions DAA (decimal adjust after addition) as well as DAS (decimal adjust after subtraction) are used for adjusting result of an addition of subtraction operation onpacked decimal numbers. Though no such instruction exists for division andmultiplication. For the cases of division and multiplication the number should be unpacked. First divided or multiplied and packed again.