FINAL REVIEW Slides "Weeks 01 through 04"

Question 1

What is professor Adams’ Email

Answer 1

gba@purdue.edu

Question 2

What is software?

Answer 2

Description of a computation expressed in a programming language, any necessary data, and documentation

Question 3

What executes software?

Answer 3

An interpreter: A system that directly executes instructions expressed in a programming language

Question 4

what are compiled programming languages?

Answer 4

high-level programming languages without an interpreter are compiled

Question 5

memorize and look at the diagram of compiling for C (Figure 4.6, slide 21)

Answer 5

ok daddy

Question 6

which step in the figure passes C language statements from input to output unchanged?

Answer 6

preprocessor

Question 7

_____ code is interpreted by a machine

Answer 7

object

Question 8

Where was the germanium crystal made?

Answer 8

Purdue

Question 9

Today electronic computers are built from _____ elements

Answer 9

Silicon (Si)

Question 10

Basic Capabilities an interpreter should have:

Answer 10

-Accept input
-Store values (include the memory function)
-Update / change existing values (variables)
-Compute (perform functions on value(s))
-Create output

Question 11

Harvard Architecutre:

Answer 11

Had two separate memories, one for instruction memory and one for data memory. Also had processor (circuit to carry out computation) and input/output

Question 12

Von Neumann Architecture:

Answer 12

One memory for both program and data, also had processor and I/O. Design was more flexible, and hence, economical, however less secure than Harvard since there was only 1 memory.

Question 13

How many distinct bands in volatge?

Answer 13

2

Question 14

4 parts of digital logic signal voltage waveform

Answer 14

1) low level 2) rising edge 3) high level 4) falling edge

Question 15

how many wires does a k-bit bit string have?

Answer 15

k wires

Question 16

a collection of k wires carrying the k bits of a k bit string

Answer 16

bus

Question 17

how many distinct k-bit strings are there?

Answer 17

2^k (Product Rule of combinatorics)

Question 18

Kibi

Answer 18

2^10

Question 19

Mebi

Answer 19

2^20

Question 20

Gibi

Answer 20

2^30

Question 21

Tebi

Answer 21

2^40

Question 22

unsigned integer, base 2, weighted positional

Answer 22

Add together powers of 2 if they’re “on” (1)

Question 23

sign magnitude integer representation

Answer 23

leftmost bit represents sign: 0 = +, 1 = -, remaining bits are magnitude as usual (However, has + and - 0

Question 24

two’s complement integers

Answer 24

Weighted, but MSB weight is negative:
-2^(n-1), + 2^(n-2), + …, + 2^1, + 2^0

Question 25

Given a bit string A, how do you obtain -A using 2's comp?

Answer 25

flip bits and add 1

Question 26

sign extension:

Answer 26

drag the bits out to go from 4 bit to 8 bit representation (in 2's comp)

Question 27

big endian:

Answer 27

most significant bye, "Big" byte, comes first (placed in lowest-numbered memory location), in MSB to LSB order

Question 28

Little endian:

Answer 28

the reverse of big endian; least significant byte, "little" byte, placed in lowest address followed from remaining bytes in LSB to MSB order

Question 29

True or false: Order of bits within a byte is NEVER changed for big / little endian

Answer 29

True

Question 30

what do you need to know to define floating point?

Answer 30

Number of bits, sizes of fields within the bit string, encoding used for each field

Question 31

precision:

Answer 31

resolution of a representation system -defined as the minimum difference between any two representations -precision of 32-bit integers is +/-1

Question 32

range:

Answer 32

the bounding number pair (smallest, largest) of a given representation - for 32-bit unsigned integers range is (0, 2^32 - 1)

Question 33

32 bit IEEE Floating Point Standard 754 has:

Answer 33

32 bits: 1 sign bit (31), 8 exponent bits (23-30) 23 bit mantissa (0-22)

Question 34

64 bit IEEE Floating Point Standard 754 has:

Answer 34

64 bits: 1 sign bit (63) 11 exponent bits (52 - 62) 52 bit mantissa (0-51)

Question 35

The IEEE 754 representation fields are sign, ____ exponent, and mantissa

Answer 35

biased

Question 36

Normalized mantissa has ___ significant digit(s) to the left of the radix point

Answer 36

One

Question 37

a k-bit pointer has how many locations in memory?

Answer 37

2^k locations

Question 38

how many bits would a register be that's formed from four 1-bit latches

Answer 38

4-bits

Question 39

a decoder is a circuit with:

Answer 39

n input wires with voltages to encode a memory address, A, from a set of 2^n memory addresses 2^n output wires, one for each available memory address

Question 40

selects 1 of 2_n k-bit input buses to connect to the k-bit output bus

Answer 40

multiplexer, used to read (copy) bits from a memory location

Question 41

connects the k-bit input bus to 1 of the 2^n k-bit output buses

Answer 41

demultiplexer, used to write bits into a memory locations

Question 42

transporting a bit string from one of many storage locations to a processor circuit is called a ____

Answer 42

fetch

Question 43

clock rate upper bound set by _____

Answer 43

worst case circuit propagation delay

Question 44

CPU Time =

Answer 44

(Instructions / Program) * (Clock cycles / Instructions) * (seconds / clock cycle) = (seconds / program)

Question 45

True or false: When last instruction is executed, computer keeps running

Answer 45

True; need an idle loop or else computer will crash without any instructions

Question 46

what is the process called that starts the fetch / execute cycle?

Answer 46

bootstrapping

Question 47

What are the machine instruction fields?

Answer 47

Opcode | operands 1, 2, ... | Results

Question 48

opcode is...

Answer 48

selects ALU result to use, aka what to do

Question 49

operands are...

Answer 49

input to ALU, see opcode to determine how many (if any) are needed for that opcode

Question 50

results are...

Answer 50

a pointer to a storage location, also optional depending on the opcode used

Question 51

2 choices for machine instruction bit string length:

Answer 51

fixed length and variable length

Question 52

variable length machine instruction:

Answer 52

concatenate fields with no limitations on number of or sized of the fields

Question 53

fixed length machine instruction:

Answer 53

encode all instructions in a fixed number of bytes

Question 54

advantages / disadvantages of variable length machine instruction

Answer 54

Adv: -unlimited capability of ISA, just add bytes -can select short encodings for commonly occurring instructions to reduce program size Disadv: -hard to prevent Marketing from adding to ISA -instruction decryption is complex: how many bytes to examine, what do they say? -makes hardware slower

Question 55

advantaged / disadvantages of fixed length machine instruction

Answer 55

adv: -easy to quickly fetch a fixed size object from memory -instruction decryption is fairly simple -ISA criteria are largely technical because cannot add byres Disadv: -hard to expand ISA

Question 56

True / False: Operands and Result fields drive up instruction length

Answer 56

True, 3 memory pointer fields, memory locations are 1 byte in size

Question 57

What do compilers do?

Answer 57

Translate HLL to target language

Question 58

Hiding underlying details

Answer 58

Abstraction

Question 59

Operation result is greater than max representable value

Answer 59

Overflow

Question 60

Result is less than smallest representable value

Answer 60

Underflow

Question 61

Set of operations chosen

Answer 61

ISA