Solution:

Data Transfer:

• Data refers to groups of bits that convey some type of information.

• Binary data, which are represented by digital waveforms, must be transferred from one device to another within a digital system or from one system to another in order to accomplish a given purpose.

• For example, numbers stored in binary form in the memory of a computer must be transferred to the computer’s central processing unit in order to be added.

• The sum of the addition must then be transferred to a monitor for display and/or transferred back to the memory.

• As illustrated in Figure, binary data are transferred in two ways: serial and parallel.

(a) Serial transfer of 8 bits of binary data:

• When bits are transferred in serial form from one point to another, they are sent one bit at a time along a single line, as illustrated in Figure(a).

• During the time interval from t0 to t1 , the first bit is transferred. During the time interval from t1 to t2 , the second bit is transferred, and so on.

• To transfer eight bits in series, it takes eight time intervals.

(b) Parallel transfer of 8 bits of binary data:

• When bits are transferred in parallel form, all the bits in a group are sent out on separate lines at the same time.

• There is one line for each bit, as shown in Figure (b) for the example of eight bits being transferred.

  -To transfer eight bits in parallel, it takes one-time interval compared to eight time intervals for the serial transfer.

• To summarize, an advantage of serial transfer of binary data is that a minimum of only one line is required.

• In parallel transfer, a number of lines equal to the number of bits to be transferred at one time is required.

• A disadvantage of serial transfer is that it takes longer to transfer a given number of bits than with parallel transfer at the same clock frequency.

• For example, if one bit can be transferred in 1 ms, then it takes 8 ms to serially transfer eight bits but only 1 ms to parallel transfer eight bits.