CSE331

4a.asm

org 100h

; Set the address
MOV AX, 3010h
MOV DS, AX
MOV BX, 0000h

; Move the contents of the selected address to BL
MOV BL, BYTE PTR DS:[BX]

; Copy BL to BH to do some calculations regarding odd/even
MOV BH, BL
; BH will only have the LSB
AND BH, 0001h
; Is LSB = 0?
CMP BH, 0000h

; Copy BL to AL for port output
MOV AL, BL

JZ EVEN
JNZ ODD

; odd
ODD:
    OUT 03h, AL
    JMP EXIT
; even
EVEN:
    MOV DX, 0303h
    OUT DX, AL
    JMP EXIT ; not necessary, but keeping it for consistency
    
EXIT:
    ret
    

4b.asm

org 100h

; BL = Arbitrary
MOV BL, 10111001b
MOV BH, 0

MOV CX, 8

L:
    SHR BL, 1
    ADC BH, 0

LOOP L

; BH now has the number of set bits in BL

ret

4c.asm

org 100h

; BL = Arbitrary
MOV BL, 00001001b

XOR BL, 10000000b

AND BL, 10000000b

CMP BL, 00000000b

JZ PS
JNZ NG

; positive
PS:
    MOV DL, 00h
    JMP EXIT
    
; negative
NG:
    MOV DL, 01h
    JMP EXIT
    
EXIT:
    ret

4d.asm

org 100h

; BL = arbitrary
MOV BL, 9AH
AND BL, 0F0H

CMP BL, 90H
JG GT
JNG LT

; BL's higher nibble > 9
GT:
    MOV AL, BL
    OUT 00h, AL
    JMP EXIT
; BL's higher nibble <= 9
LT:
    MOV AX, 0F000h
    MOV DS, AX
    
    MOV BX, 0FF2h
    MOV BYTE PTR DS:[BX], BL
    JMP EXIT
    
EXIT:
    ret