Homework 16

ECE 252 Introduction to Electrical Engineering
Lesson 16. Computer Circuits Homework
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-toface, 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 sign each problem solution at 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. Do you think the homework policy is
fair? What can be done to improve the policy? 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) The decimal equivalent of the binary number 0111 1011 is ___________________________
b) A MOSFET with a positive gate-to-source voltage acts like a(n) ______________ switch between the source
and drain.
c) RAM is _______________________. This means that RAM loses its data when the power is shut off.
d) SDRAM is a type of (DRAM, SRAM, ROM, Flash).
e) DRAM requires ________________________, the periodic reading and updating of its memory cells.
f) Which type of memory would most likely be found as the main memory of a laptop computer?
(DRAM, SRAM, ROM, Flash).
g) High-Z, high impedance, or floating are terms referring to one of the output states of a
_________________________________ buffer.
h) It is not possible to rewrite single bytes in flash memory. Instead, memory must be erased in
__________________ before new memory values can be stored.
i) Microcontrollers are usually found in ___________________________ applications. That is, the application is
intended for a special purpose, rather than a general purpose.
k) The continuing exponential increase in processing power of microprocessors is called ________________
l) Modern microprocessors break up each machine instruction into several parts, such as instruction fetch,
instruction decode, data fetch, execution, and write-back. This process is called _____________________, and it
allows speed-up through simultaneous execution of different parts of different instructions.
m) _____________________ memory stores recently-used program code and data that can be quickly accessed
for reuse.
n) Reduction in the size of transistors on microprocessor and memory chips has resulted in greater power density
(and therefore heat). One method used to mitigate this problem is lowering the operating ___________________.
o) What type of computer architecture is characterized by few instructions, all of the same length and all
executing in the same amount of time? ________________________________
p) A certain A/D converter has an input analog signal varying from 0.1 V to 3.5 V and containing frequencies in
the range of 30 Hz to 200 Hz. To get an accurate representation of the analog signal, the A/D converter should
have a sampling rate of at least __________________ samples/second.
q) What company (in 1971) made the first microprocessor? ________________________
r) What two Steve’s founded Apple in the mid-1970s? ____________________ and ____________________.
Signatures: ________________________________________________________________________
3. An 8-bit A/D converter has Vref- = -2.5 V and Vref+ = 4.5 V.
a) If vin = -5 V, what is the binary value on the A/D output pins?
b) If vin = 6 V, what is the binary value on the A/D output pins?
c) If vin = -.45 V, what is the binary value on the A/D output pins?
d) Explain why the binary output value should never be allowed to rise above 1111 1110.
e) EXTRA CREDIT: If this were a 12-bit A/D converter, what would be the answer to part c)?
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?
Signatures: ________________________________________________________________________
BONUS (No partial credit): What is Dr. Cleaver's age in hexadecimal? (Don't ask, because I’m not telling.)
Signatures: ________________________________________________________________________