#1. How many cells can be in a computer's main memory if each cell's address can be represented by two hexadecimal digits? What if four hexadecimal digits are used? Explain your answer.
Hexadecimal digits is a base 16 number system and it ranges between 0 and F i.e. 0 - 9 and A - F (10 -15). (Table 1 below shows binary, decimal and hexadecimal representation). Two hexadecimal digits will be between 00 and FF and this will make up to 256 cells i.e. 0 – 255 (16 bits) and for four hexadecimal digits will be between 0000 – FFFF and this makes up to 65536 cells i.e. 0 – 65535 (32 bits).
BINARY NUMBERS| DECIMAL NUMBERS| HEXADECIMAL NUMBERS|
0000| 0| 0|
0001| 1| 1|
0010| 2| 2|
0011| 3| 3|
0100| 4| 4|
0101| 5| 5|
0110| 6| 6|
0111| 7| 7|
1000| 8| 8|
1001| 9| 9|
1010| 10| A|
1011| 11| B|
1100| 12| C|
1101| 13| D|
1110| 14| E|
1111| 15| F|
Table 1: Decimal and hexadecimal representation
#2. Suppose that only 50GB of your personal computer’s 120GB hard-disk drive is empty. Would it be reasonable to use CDs to store most of the material you have on the drive as a backup? What about DVDs? Explain your answer.
With 120GB of storage and 50GB space free that amounts to 70GB of data to back up, the maximum a CD can take is 700MB (0.7GB) that amounts to 100 CDs. The size of an average DVD-R is about 4.7GB this will make up to 15 DVDs and this makes a lot sense than using 100 CDs.
#3. Suppose three values (x, y, and z) are stored in a machine's memory. Describe the sequence of events (loading registers from memory, saving values in memory, and so on) that lead to the computation of x + y + z. How about (2x) + y?
I. To compute x + y + z, each of the values must be retrieved from memory and placed into the register, the sum of x and y must be computed placed into the registry and the value of the sum must be added to z and...