Could you write definitions of codes clearly ? (assembly code)

CNT3 APORT3 BPORT BPORT3 Q1 Q2 Q4. START: MAIN EQU 0FFFFH EQU 3FDOH EQU 3FD2H EQU 0FFFBH EQU 1EH EQU 2DH EQU 4BH EQU 87H CODE SEGMENT ASSUME CS: CODE, DS: CODE ORG SP, 2000H MOV MOV AX, CS MOV DS, AX MOV AL 90H MOV DX, CNT3 OUT DX,AL MOV a1, 80H DX,APORT3 MOV IN AL DX NOT AL DX,BPORT MOV OUT DX,AL CMP AL ,80H JE J2 CMP AL 01H JE J1 JMP MAIN