CODEWITHSUNDEEP
assemblyx86dos
Dwayne Radar
Dwayne Radar

Reputation: 195

purpose of 'and' in assembly

Can someone define me the exact purpose of the and keyword in assembly? I have provided a code here can someone explain me what the and does in this code? By the way the and is located somewhere under begin just for you to locate it easily.

code segment
assume cs:code;ds:code
org 100h

begin:

mov ah, 09
mov dx, offset msg1
int 21h

mov ah,01h ;ask user
int 21h
and al,01h
jz EVENn
mov ah, 09 ;display string
mov dx, offset oddmsg
int 21h
jmp ENDd

EVENn:

mov ah, 09 ;display string
mov dx, offset evenmsg
int 21h

ENDd:
int 20h

msg1:db 'enter a number: $'
evenmsg:db 0ah,0dh, 'EVEN $'
oddmsg:db 0ah,0dh, 'ODD$'

code ends
end begin

Upvotes: 0

Views: 4032

Answers (1)

Guffa
Guffa

Reputation: 700152

The and opreator does a logical and operation.

In this case it's used to mask out a single bit in a value. If you for example get the value 6Dh in al (the character m read from STDIN), the operation leaves only the least significant bit:

6Dh  01101101
01h  00000001
--------------- and
     00000001

An even character code gives the result 00h, and an odd character code gives the result 01h.

Upvotes: 1

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