Midterm1

Question 1

What is a signed number

Answer 1

A negative number

Question 2

When do u use imul, idiv

Answer 2

In negative numbers

Question 3

Div edx,eax stores quotient and remainder where?

Answer 3

Quotient in eax

Remainder in edx

Question 4

How to detect overflow in unsigned equations

Answer 4

Carry flag is set (Jc,jnc)

Question 5

How to detect overflow in signed equations

Answer 5

Overflow flag is set (jo,Jno)

Question 6

How to tell if CF is set?

Answer 6

1: hex addition, if last addition in equation has a carry

Question 7

How to tell if OF is set?

Answer 7

Think of the two numbers as signed:
If they are a different sign then OF=0 no matter what

If they are the same sign, OF=1 only if the result of adding the two together makes no sense (sign+sign=unsign)

Ex. AF+84 = 33
Adding Two negative should not make it a positive

Question 8

When moving a greater quantity to a smaller quantity the bits on what side are dropped?

Answer 8

Left

Question 9

When increasing with movsx what happens?

Answer 9

Adds replicas of signed bit to the left

Question 10

When increasing with movzx what happens?

Answer 10

Adds zeros to the left

Question 11

What are jump instructions for unsigned numbers?

Answer 11

JE,JNE,JB,JNAE,JBE,JNA,JA,JNBE,JAE,JNB

B=below
A=above

Question 12

Jump instructions for signed numbers

Answer 12

JE,JNE,JL,JNGE,JLE,JNG,JG,JNLE,JGE,JNL

G=greater
L=less

Question 13

What is the memory layout in little endian?

Answer 13

If any memory that is not db, hex representation is stored backwards

Ex.
dd AABBCCAA

In register: AACCBBAA

Question 14

Mov eax,L2

Answer 14

Will make the “pointer” point to the first byte of L2

Question 15

Add eax,2

Answer 15

Will make the “pointer” move 2 bytes within the register

Question 16

Mov word[eax], 23

Answer 16

Will save the hex value of 23 where ever the pointer is pointing too as 4bytes (because of word)

Question 17

Adc al,0

Answer 17

Will make al+=0+carry

Basically will save 1 or 0 to determine with carry but was flipped on or off

Question 18

What can xor be used for?

Answer 18

To flip a bit

Ex.

XOR eax,ebx

Will flip the bit in eax when ebx where ebx is pointing to

Question 19

Octal/binary/hex -> decimal

Answer 19

base^n+……+#base^0=base decimal number

This goes for any bases
Binary (2), octal (8), hex(16)

Question 20

Binary -> decimal

Answer 20

Only is there is a one, you add the the decimal representation together:

Ex: 1010
8+2=10

256 128 64 32 16 8 4 2 1

Question 21

Binary arithmetic

Answer 21

1+1= 0 and a carry
0+0=0
1+0=1

Question 22

Hex addition?

Answer 22

If overflows, start back from 10, result will be whatever u counted when I start back from 10 and a carry

Question 23

A

Answer 23

10

Question 24

B

Answer 24

11

Question 25

C

Answer 25

12

Question 26

D

Answer 26

13

Question 27

E

Answer 27

14

Question 28

F

Answer 28

15

Question 29

A binary with d bits corresponds with integer values between...

Answer 29

0 and 2^d-1 bits

Question 30

1byte= .. bits

Answer 30

8 bits

Question 31

2bytes =

Answer 31

Word (dw) 16bits

Question 32

4bytes=

Answer 32

Double (dd) 32bits

Question 33

8bytes =

Answer 33

Quad word (dq)

Question 34

In binary, leftmost is 1 it's is

Answer 34

Negative, signed

Question 35

Twos complement?

Answer 35

In binary, flip bits and add 1

Question 36

Range of unsigned 1byte number

Answer 36

00-FF (0-254)

Question 37

Binary subtraction

Answer 37

1-0=1 1-1=0 0-0=1

Question 38

Charles Babbage made what?

Answer 38

Difference machine

Question 39

Von-Neumann structure

Answer 39

CPU,memory,input/output system

Question 40

1950, kilby and noice made

Answer 40

An integrated circuit

Question 41

1948 Bardeen Brattain and Shockley made...

Answer 41

Transistors

Question 42

1 kilobyte is

Answer 42

1024 bytes

Question 43

1 megabyte is

Answer 43

220 bytes

Question 44

1 gigabyte =

Answer 44

230 bytes

Question 45

1 terabyte =

Answer 45

240 bytes

Question 46

Fetch decode execute cycle

Answer 46

Fetches the next program instruction from memory, Decodes it, And the ALU executes the computation The new register value is stored in memory

Question 47

Oppose and operands are

Answer 47

Opcode= what instruction computes Operands= the input to the computation

Question 48

Compiler=> assembler => CPU

Answer 48

Compiler compiles high level code, Assembler create machine code

Question 49

Resx does?

Answer 49

Resx are uninitialized data Ex: L20 resd 100 100 in initialized 2-byte words

Question 50

``` Operands: Register Memory Immediate Implied ```

Answer 50

``` Register : are registers Memory : specifies an address in memory Immediate : a fixed number ex: add eax,2 Implied: not actually encoded in the instruction Ex: inc eax (really means eax+1) ```

Question 51

Eax= Ax= Al/ah=

Answer 51

32 bits 16 bits 8bits

Question 52

Unsigned can overflow

Answer 52

If result is negative or too big(has a carry)

Question 53

Short jump

Answer 53

Within 128 bytes in memory

Question 54

Near jump

Answer 54

Anywhere in segment, 4byte displacement

Question 55

Shl,shr is for .... numbers

Answer 55

Unsigned

Question 56

Sal,sar is for ....

Answer 56

Signed numbers, new bits entering are copies of the sign bit (Adds zero if bits added in on right, Most likely adds 1s if bits entering from left)

Question 57

Rol,ror

Answer 57

Rotate shifts

Question 58

Rcl,rcr

Answer 58

The carry flag and the source are rotated as one quantity Ex if have a 16 bit item it's technically is a 17bit item

Question 59

AND

Answer 59

Only turns on (1) if double 1 Turn off bits

Question 60

OR

Answer 60

Only turns off (0) if double 0 Turn on bits Put f in 000F00h where u want to turn but on

Question 61

XOR

Answer 61

Only turns on (1) if not double 0 or double 1 Flip bits By using F at any place u want to flip the bits

Question 62

NOT

Answer 62

flips all of the bits

Question 63

Decimal -> hex

Answer 63

Decide decimal number by 16 Take answer and multiple 16, and then add the remainder Repeat until 0 Remainders, in hex, will be answer Ex: 1237=77*16+5 77=4*16+13 4= 0*16+4 Hex answer= 4D5

Question 64

Shifting to the left is the equivalent of....

Answer 64

Multiplying by 2