Final Exam -- Closed book section

8 May, 1995

Choose the most appropriate phrase for terminating each sentence. Circle your choice. There are twenty multiple-choice questions. Each question counts 1.5 points.

One statement of DeMorgan's theorem is

• x + x y = x .
• x + x' = 1 .
• (x y)' = x' + y' .
• x (y + z) = x y + x z .

One law of associativity for Boolean algebra states that

• x + x y = x .
• x + x' = 1 .
• (x y)' = x' + y' .
• x (y + z) = x y + x z .

Assembly language statements look something like

• A056.
• STA X.
• insert tab A into slot B.
• #ifdef POSIXDEFS.

Sigma (1, 3, 4) is an example of a Boolean function specified with

• Karnaugh maps.
• sum-of-products notation.
• DeMorgan simplification.
• JK flip flops.

• The Boolean expression x + x' y equals
• x .
• x + x' .
• x + y .
• y .

The full adder has

• two inputs and two outputs.
• two inputs and three outputs.
• three inputs and two outputs.
• three inputs and three outputs.

Circuits whose outputs are determined solely by their present inputs are called

• Boolean circuits.
• combinational circuits.
• sequential circuits.
• digital circuits.

VLSI is an abbreviation for

• Very Large Scale Integration.
• Very Large Sequential Integration.
• Very Large Semiconductor Integration.
• Very Large Selector Integration.

A 8-to-1 line multiplexer has

• two selection inputs.
• three selection inputs.
• seven selection inputs.
• eight selection inputs.

The third state of a three-state (or TRI-state) bus is called the

• high-impedance state.
• closed state.
• resistent state.
• analog state.

The part of a machine instruction that specifies which operation should be performed is commonly called the

• indirect bit.
• RAM disc.
• state table.
• opcode.

Flip-flops that change states on the start or end of a clock pulse are called

• value-driven.
• edge-triggered.
• sequential.
• combinatorial.

The number of different values that can be stored in an eight-bit register is

• 32.
• 128.
• 256.
• 1024.

When people are talking about computers, 1k usually means

• 1000.
• 1024.
• one clock cycle.
• one kilometer.

The number of RTL statements used to specify the basic computer of the textbook was approximately.

• 4.
• 40.
• 400.
• 4000.

Usually, the first phase of a machine's instruction cycle is the

• store phase.
• decode phase.
• index phase.
• fetch phrase.

On a modern micro-processor the number of phases required to execute an addition instruction is about

• 5.
• 50.
• 500.
• 5000.

The microcode of a computer is usually stored in the

• dynamic RAM.
• control memory
• hardwired array.
• micro registers.

Before the code you write is executed on the computer, it is translated into

• machine language.
• microcode.
• Boolean logic.
• register transfer language.

The program you used to simulate circuits in some homework assignments was called

• csim.
• cc.
• diglog.
• unix.

Problem 1. (3 points)

What is the result of performing the following three shift operations on an eight-bit register containing the value 10101011?

• arithmetic left shift
• circular left shift
• logical right shift

Problem 2. (2 points)

Draw the truth table for an AND gate.

Problem 3. (2 points)

How is the decimal number 26 represented as a binary number?

Problem 4. (2 points)

How is the number -18 represented as a eight-bit twos-complement binary number?

Problem 5. (3 points)

What is the meaning of the following RTL statement:

• p: R <- S, S <- T

Problem 6. (2 points)

What decimal number corresponds to the binary point number 110.1?

Problem 7. (3 points)

Describe how a skip instruction, such as SPA for "skip if accumulator positive", can be used to implement the following C if-then statement

if (c<0)
  c = 0 ;

There is absolutely no need to write any code. You can give your answer in English.

Problem 8. (3 points)

Draw the graphical representation for the following three gates.

• AND
• NOT (invertor)
• NAND

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