ence260 exam (computer architecture and embedded systems)

What is an embedded system

A small computer that has a specific task

Personal computer versus embedded system task type

General task versus specific task

What are the three main components of a computer

Memory and Buses and Central processing unit and Internal peripherals

What is a logic statement

A sentence that answers a yes or no question

What numerical values represent the boolean states FALSE and TRUE

0 and 1 respectively

What is the formula for the number of possible combinations in a sequence

M to the power of N where M is states per digit and N is sequence length

How many bits are in a byte

8 consecutive bits

What is a word in computer architecture

The default number of bits manipulated by a microcontroller CPU

What is the zeroth bit also referred to as

The least significant bit or LSb

How do you calculate the value of an unsigned binary sequence

The sum of d sub n times 2 to the power of n

What is a shortfall of the sign magnitude representation

It has a duplicate representation for positive and negative zero

Why is twos complement widely used for signed integers

It removes the duplicate zero and lends can perform subtractions using the same adder

What are the two steps to convert a positive binary number to a negative twos complement number

Invert each digit and add one ignoring overflow

How many bits are represented by a single hexadecimal digit

Exactly four bits

What is half a byte called

A nibble

What are the three components of a 32 bit floating point binary number

Sign bit and Exponent and Fractional part

How many bits are used in standard ASCII character encoding

7 bits

What type of logic circuit gives a system memory because output depends on previous states

Sequential logic

What is the simplest form of sequential circuit

The SR latch

What is an array of flip flops called

A register

What does the asterisk character do to a pointer in C

It gives the value pointed to by the address

What does the ampersand character do to a variable in C

It gives the memory address of the variable

What defines Von Neumann architecture

Programme memory and data memory are stored in the same physical memory space

What defines Harvard architecture

Programme memory and data memory are stored in separate memory spaces

What does the data bus do

Transports actual data between the CPU and memory and is bidirectional

What are the three fundamental logical functions

NOT and AND and OR

What does De Morgans Law state about the inverse of A AND B

It is equal to NOT A OR NOT B

What does De Morgans Law state about the inverse of A OR B

It is equal to NOT A AND NOT B

How must adjacent cells in a Karnaugh map differ

By a single variable

What is a minterm

A term written solely as ANDs of all inputs or their inverses where all inputs appear exactly once

What is the standard order of operations for boolean logic

NOT then AND then OR

What is the function of the Arithmetic Logic Unit

It performs arithmetic and comparisons and logic operations

Why are general purpose registers physically close to the ALU

To enable fast access and performance

What does the control and execute unit do

It controls data flow to the ALU and interprets instructions from program memory

What does the Zero flag indicate in the status register

A zero result in an arithmetic or logic operation

What does the Program Counter store

The address of the next instruction in the program memory

What are the outputs of a half adder

Sum and Carry

How is a full adder different from a half adder

It can accept an incoming carry bit

What does an n bit decoder produce

Exactly one HIGH output among 2 to the power n outputs

What does the input of a decoder represent

A binary number selecting one output

What is meant by one hot decoder output

Exactly one output is HIGH at a time

How does a decoder help select memory

It activates the row corresponding to the requested address

What output is HIGH in a 2 bit decoder for input 00

O0

What output is HIGH in a 2 bit decoder for input 01

O1

What output is HIGH in a 2 bit decoder for input 10

O2

What output is HIGH in a 2 bit decoder for input 11

O3

What logic produces O0 in a 2 to 4 decoder

NOT A1 AND NOT A0

What logic produces O1 in a 2 to 4 decoder

NOT A1 AND A0

What logic produces O2 in a 2 to 4 decoder

A1 AND NOT A0

What logic produces O3 in a 2 to 4 decoder

A1 AND A0

What does an encoder do

It converts one active input into its binary input number

What assumption does a basic encoder make

Exactly one input is HIGH

How many outputs does an encoder with 2 to the power n inputs have

n outputs

What does an 8 to 3 encoder output

The 3 bit number identifying the active input

What forms A0 in an 8 to 3 encoder

I1 OR I3 OR I5 OR I7

What forms A1 in an 8 to 3 encoder

I2 OR I3 OR I6 OR I7

What forms A2 in an 8 to 3 encoder

I4 OR I5 OR I6 OR I7

What is the purpose of a multiplexer

Select one of several inputs and connect it to the output

How many inputs can n mux selector bits choose from

2 to the power n inputs

What does a 2 to 1 mux output when S is 0

I0

What does a 2 to 1 mux output when S is 1

I1

What Boolean expression describes a 2 to 1 mux

NOT S AND I0 OR S AND I1

What is a bus multiplexer

Parallel muxes that select between multi bit input buses

What does an 8 by 2 to 1 bus mux contain

Eight parallel 2 to 1 muxes sharing one selector

What is the purpose of a demultiplexer

Route one input to one selected output

What does a 1 to 2 demux do when S is 0

Routes the input to O0

What does a 1 to 2 demux do when S is 1

Routes the input to O1

What happens to unselected demux outputs

They remain LOW

How are muxes and demuxes opposite

A mux selects an input while a demux selects an output

How can an ALU support several Boolean operations

Compute them in parallel then use a mux to select one

What role does the mux play in an ALU

It selects which operation result becomes the output

Why is XOR useful for controlled inversion

XOR with 0 preserves a bit and XOR with 1 flips it

How does an ALU switch between addition and subtraction

XOR each B bit with Sub and also send Sub to carry in

What happens when Sub is 0 (not what operation but the logistics behind it)

B passes unchanged and carry in is 0

What operation occurs when Sub is 0

The adder computes A plus B

What happens when Sub is 1

Every B bit is inverted and carry in adds 1

What operation occurs when Sub is 1

The adder computes A minus B

Why is carry in set to Sub during subtraction

It supplies the plus 1 needed after inverting B

How are embedded systems typically integrated

As purpose built electronics inside a larger device

What type of CPU is commonly used in embedded systems

A microcontroller

What microcontroller is used in the UCFK4

ATmega32U2

What is a microprocessor

A CPU implemented on a single integrated circuit

Where does a microprocessor usually get memory and peripherals

From components located off chip

What is a microcontroller

A CPU with memory and peripherals integrated on one chip

What hardware is commonly integrated into a microcontroller

Memory and I O ports and timers and other peripherals

What type of processor is commonly used in desktop computers

A microprocessor

How do embedded systems generally compare in physical size

They are smaller than general purpose computers

How do embedded systems generally compare in cost

They are cheaper than general purpose computers

How do embedded systems generally compare in memory capacity

They usually have less memory

How do embedded systems generally compare in computing power

They usually have less computing power

How do embedded systems generally compare in power consumption

They usually consume less power

What are the three registers that control each I O port

DDRx PORTx and PINx

What does DDRx control

Whether each port pin is an input or an output

What does a zero bit in DDRx mean

The corresponding pin is configured as an input

What does a one bit in DDRx mean

The corresponding pin is configured as an output

What does PORTx control for an output pin

The voltage state driven on the corresponding pin

What does a zero bit in PORTx mean for an output pin

The pin is driven LOW

What does a one bit in PORTx mean for an output pin

The pin is driven HIGH

What does PINx provide

The current logic state read from the port pins

How are pin numbers matched across DDRx PORTx and PINx

The same bit position refers to the same physical pin