CS 135 Homework 1: Fall 2010

Due: September 12th 11pm.

 

Ques.1: Number conversions.

(a)    Convert the binary number 01100101 to decimal.

(b)   Convert the decimal number 17 to an 8-bit unsigned binary representation.

(c)    Convert the 8-bit 2’s complement binary number 11001010 to decimal.

(d)   Convert the decimal number -101 to an 8-bit 2’s complement binary representation.

(e)    Convert the decimal number -101 to an 8-bit signed magnitude binary representation.

(f)    Convert the 8-bit unsigned binary number 11011110 to hexadecimal.

(g)    Convert the unsigned hexadecimal number 24 to unsigned 8-bit binary.

 

Ques.2: Arithmetic and logical operations.

Let A = 00110101 and B = 11001011 be 2’s complement integers. Compute the following. Assume a fixed width of 8 bits (i.e., your answers must be 8 bits). Please show your work  -- failure to do so means you get zero points.

(a) A +B

(b) A OR B

(c) A AND B

(d) B A

(e) A B

(f) A +B’ + 1  (B’ refers to complement of B)

 

 

Ques.3: Consider the following 8-bit 2’s complement numbers:

A = 01111111, B = 00000101, and C = 10001011. Assume that only 8 bits are available to represent values.

Show your work.

 

(a)    Evaluate A+B. Give your answer as an 8-bit 2’s complement number. Convert this number to decimal. Does this represent the sum of A and B? If your answer is No, then explain.

 

(b)   Evaluate CA. Give your answer as an 8-bit 2’s complement number. Convert this number to decimal. Does this represent the difference of C and A? If your answer is No, then explain.

 

Ques.4: Logical operations. Complete the following truth tables. The notation A’ refers to complement of logical variable A (i.e., the operation NOT A).

 

 

A

B

C

(A AND B) OR C

(A AND C) OR (B AND C)

0

0

0

 

 

0

0

1

 

 

..

..

..

..

..

1

1

1

 

 

 

A

B

C

(A AND B) AND (A’ AND B’) OR C