Memory

Question 1

how to change a value in memory

Answer 1

store in a register, change that, store back into memory

Question 2

how do we terminate a string in memory

Answer 2

null terminate eg 0x00

Question 3

psuedo code for loading a bytesized character from memory

Answer 3

ch = byte [address]

Question 4

psuedo code for storing a byte into register

Answer 4

byte [address] = ch

Question 5

ldrb means

Answer 5

load with byte

Question 6

strb means

Answer 6

store byte

Question 7

ldrh means

Answer 7

Load half word

Question 8

ldr means

Answer 8

load word

Question 9

strh measn

Answer 9

store hafl word

Question 10

str means

Answer 10

store word

Question 11

which has a reversed operand order str or ldr

Answer 11

STR

Question 12

what does rom stand for

Answer 12

read only memory

Question 13

what does ram stand for

Answer 13

random access memory

Question 14

can rom be modified by a running program

Answer 14

no

Question 15

can ram be modified by a running program

Answer 15

yes

Question 16

how to add one to address in memory and also load the byte from memory into a register (R1)
memory in r4

Answer 16

LDRB R1, [R4], #1

Question 17

what happens when we load a byte sized value from memory into a word sized register

Answer 17

byte value in stored in least significant bit,

3 remaining bytes are set to 0

Question 18

what is little endian byte storing

Answer 18

when the least significant byte of the word/halfword is stored at the lower address in memory

Question 19

what is big endian byte stroing

Answer 19

when the most significant bit of the word/halfword is stored in the lower address of memory

Question 20

default on vs code little endian or big endian

Answer 20

little endian

Question 21

how to use ldr with signed numbers

Answer 21

ldrs

Question 22

what will the remaining digits in the word be padded with if negative

Answer 22

1s