1.

*(a) How many data bits are required to store one of the decimal digits 0 through 9? *(b) How many parity bits are required to detect a single error? (c) Write a single-error detection code using even parity. Underline the parity bits. (d) What is the code distance of your code?

2.

A set of eight data bits is transmitted with the single-error correction code of Figure 9.25. For each of the received bit patterns below, state whether an error occured. If it did, correct the error.

*(a) 1 0 0 1 1 0 1 0 1 0 0 1

(b) 1 1 0 1 0 0 1 1 0 0 1 0

(c) 0 0 0 0 1 0 1 1 0 1 0 0

(d) 1 0 1 1 0 0 1 0 0 1 0 0

Figure 9.25:

3.

You have a RAID level 4 system with eight data disks and one parity disk. (a) How many disk reads and disk writes must you make to write one data stripe if you do not make use of the old data and parity values? (b) How many disk reads and disk writes must you make to write one data stripe if you do make use of the old data and parity values?

FIGURE 9.25 The position of the four parity bits in a single-error-correcting code with eight data bits. 1 2 3 4 5 6 7 8 9 10 11 12