ECE 252 Introduction to Electrical Engineering

ECE 252 Introduction to Electrical Engineering

Lesson 16. Computer Circuits Homework

Version S18Sol

Homework partner name: ______Homework partner name: ______

1. Homework policy: Copying homework and all other forms of academic dishonesty are forbidden.Use of homework assignments from previous terms is forbidden, as is looking up solutions on line, looking at the papers of others, showing others your papers, and comparing answers. Getting aid from other students on homework is acceptable if limited to general solution concepts and methods.The team members must work together, face-to-face, on all parts of the assignment, that is, dividing up the work is not permitted. To verify that you have worked together, each team member must initial each problem solutionat the time the problem is solved. If it is impossible for the team members to work together, each individual should turn in a separate homework assignment.

Please relate your experiences with applying this policy to your homework. You will be given credit so long as your comments are thoughtful and sincere.

Signatures: ______

2. Quickies. Circle the correct answer or fill in the blank:

a) SRAM is (faster than, slower than, the same speed as) DRAM.

b) How many transistors are used to make a DRAM cell? ______

c) How many transistors are used to make an SRAM cell? ______

d) The Pentium microprocessor uses (CISC, DISC, FRISC, RISC) technology.

e) Feature size in computer circuits has been decreasing for over 45 years. This makes it possible to put more transistors in the same space and increase the clock speed. But it also results in the following problems (circle all that apply): bubble propagation, dark silicon, greater quantum tunneling, more heat.

f) ______memory is memory that lies between the processor and main memory. The processor looks there first when it wants to access data.

g) Microprocessors are fast, but the processor-to-memory bus is slow. This leads to a problem called the ______.

h) A microprocessor that can fetch an instruction, decode another instruction, execute yet another instruction, and write back yet-again another instruction does this by a process called ______.

i) An embedded processor will most likely be a (microprocessor, microcontroller, ROM).

j) The analog input to an analog-to-digital converter contains frequencies that range between 750 Hz and 4000 Hz and voltages that range between 1 V and 4 V. The sampling rate of the A/D converter should be at least ______samples/second.

k) The input to a three-state buffer is logic 0. The gate of this three-state buffer is logic 0. The output of this three-state buffer is ______.

l) Which one of these devices requires refresh? (DRAM, SRAM, ROM, Flash)

m) Which one of these devices is used to make an SSD (solid-state drive)? (DRAM, SRAM, ROM, Flash)

n) (DRAM, SRAM, ROM, Flash) is usually the main memory of a PC.

o) Memory that is erased when the power is turned off is called ______memory.

p) The decimal equivalent of the binary number 1101 0110 is ______.

q) RAM stands for ______

r) A MOSFET has a gate-to-source voltage of zero. This MOSFET acts like a (closed, open, unknown) switch.

Signatures: ______

3. An 8-bit A/D converter has Vref- = -2.5V and Vref+ = 7.5V.

a) If vin = -3 V, what is the binary value on the A/D output pins?

b) If vin = 8 V, what is the binary value on the A/D output pins?

c) If vin = -.31V, what is the binary value on the A/D output pins?

d) Explain why the binary output value should never be allowed to fall below0000 0001.

e) EXTRA CREDIT: If this were a 12-bit A/D converter, what would be the answer to part c)?

a)

b)

c)

d)

e)

Signatures: ______

4. Below is a circuit made with D flip-flops. Initially, Q1 = 0, Q2 = 1, Q3 = 0, Q4 = 0. a) Explain what happens with each pulse of the clock. b) What are the values of Q1 through Q4 after two pulses of the clock? c) EXTRA CREDIT: What is this kind of circuit called?

a)

b)

c)

Signatures: ______

BONUS (No partial credit). What decimal number is represented by the following single precision floating point number in IEEE 754 format?

11000001 100010100000000000000000

The following formula may be useful:

X2 = (-1)Sign× Significand2× 2(Exponent – Bias)

Where the Significand is 1 + Fraction and Bias is 12710 (011111112).

Signatures: ______