LEC 1

Question 1

Memory Machine

Answer 1

• Input/Output communicates information between memory and outside world
• CPU manipulates information from memory
• CPU interprets information from memory as data or instructions

Question 2

How many can 8 bits represent?

Answer 2

255

Question 3

What is 16 bytes in bits in SIMD mode?

Answer 3

128

Question 4

How is byte sequence interpreted as?

Answer 4

data in continuous bit sequences

Instructions with distinct fields

Question 5

What is operation field?

Answer 5

what is to be done

Question 6

What is operand fields?

Answer 6

what is to be manipulated

• absolute value
• register number
• address of value in memorry

Question 7

Where does the CPU fetch instructions from?

Answer 7

The memory

Question 8

What type of sequences does the memory have?

Answer 8

Byte sequence

Question 9

What does the program counter do?

Answer 9

• Register
• Holds memory address for next instruction-
• Automatically increment after each instruction
• Branch instruction changes instruction sequence

Question 10

What are the examples of instructions to manipulate registers?

Answer 10

• E.g. load register with value from memory
address
• E.g. add value to register
• E.g. store value from register at memory address

Question 11

Instructions can also change program

counter with an example?

Answer 11

To change order of execution
E.g. branch to new address
E.g. branch to new address depending on values in
other registers

Question 12

What can instructions do ?

Answer 12

• manipulate registers

- Change program counter

Question 13

Machine code is very hard to?

Answer 13

• write
• read
• debug
• not portable between different CPUS
• very rarely constructed by hand
• as fast as it gets

Question 14

What is the characteristics of assembly language?

Answer 14

 One to one correspondence with machine code
• No loss of efficiency
 Assembly language is CPU specific
• No universal assembly language
• Not portable between CPUs
 Translated to machine code by assembler program
• How to write very first assembler…?
 Improvement from machine code but very limited
abstractions
 Hard to read/write/debug
 Specialist skill
 E.g. device drivers, BIOS, small embedded systems,
(part of) computer OS

Question 15

What is the textual memory description of assembly language?

Answer 15

• Address -> Label

* Bit sequence ->Constant

Question 16

What is the textual instruction fields of assembly language?

Answer 16

• Operations ->mnemonics
• Operands
Value -> Constants
Address->Label
Register ->Mnemonic

Question 17

What is C’s overview?

Answer 17

Strict, strongly typed, imperative system
programming language

Combines high-level constructs with low
level access to type representations and
memory

Question 18

What does stack in memory organisation contain?

Answer 18

• Allocated
automatically
• Global declarations
• Local declarations
• Function parameters

Question 19

what does heap do in memory organisation?

Answer 19

• Allocated by program
• C.f. Java “new”
• No garbage collection

Question 20

what does type var_name do?

Answer 20

• Allocates space for new variable of type

called name on stack

Question 21

what does var_name do?

Answer 21

• Can contain letters, digits and “_”
• Must start with a letter
• C convention
lower case = variable name
UPPER CASE = symbolic constant

Question 22

Can group declarations for same type?

Answer 22

yes

Question 23

What does the amount of space for type depend on?

Answer 23

type
platform
compiler

Question 24

How to measure type sizes in bytes?

Answer 24

int sizeof(type)

returns the number of bytes for type

Question 25

Declaration: type name

Answer 25

Associates name with enough memory for

type

Question 26

&name

Answer 26

Address of 1st byte allocated to variable

name

Question 27

What is constant? as expression

Answer 27

value of constant

Question 28

What is name? as expression

Answer 28

value from memory