Data Acquisition

0, 1, 2, 3, 4, 5, 6, 7Hence, the number 23471.6 8 would be represented as below: Table F.7Octal weighting structureThis translates into the following decimal number2 X 8 4 + 3 X 8 3 + 4 X 8 2 + 7 X 8 1 + 1 X 8 0 + 6 X 8 -1 = 10041.7510F.6 Binary coded decimalThe Binary coded decimal approach can be used to convert decimal numbers into binaryform and assigns four (4) binary digits to each decimal digit.For example, 4 decimal numbers could be represented as: This is represented as four decimal numbers indicated as follows:0 X 2 3 + 1 X 2 2 + 0 X 2 1 + 1 X 2 0 + 0 X 2 3 + 1 X 2 2 + 1 X 2 1 + 1 X 2 0 0 X 2 3 + 1 X2 2 + 0 X 2 1 + 0 X 2 0 + 0 X 2 3 + 0 X 2 2 + 0 X 2 1 + 1 X 2 0= 5 7 4 1 10There is a certain amount of wastage in this coding system as the maximum 4 bit binarycombination for BCD is 1001 2 or 9 10 . The binary combinations 1010 to 1111 are unused(and illegal) in a BCD encoding system.BCD notation is useful for applications where absolute precision is required (unlikefloating point notation which gives a high precision but no guarantee of absoluteprecision). Unfortunately, a specialized method of arithmetic operations has to be builtinto the system, as normal binary arithmetic is inadequate.F.7 Binary coded octal systemsThe binary coded octal system uses 8 bits to represent 3 digit octal numbers from 000 8 to377 8 . This approach is not often used today.The largest binary coded octal number could be represented as: This is represented as three octal numbers1 X 2 1 + 1 X 2 0 1 X 2 1 + 1 X 2 0 1 X 2 2 + 1 X 2 1 + 1 X 2 0=3 7 7 8