Lab2

        org 100h
Start:
        mov ah, 09h
        mov dx, Condition
        int 21h

        mov ah, 09h
        mov dx, NewLine
        int 21h

        mov ah, 0ah
        mov dx, Buffer
        int 21h

        mov ah, 09h
        mov dx, NewLine
        int 21h

checkLength:

        mov bh, [Buffer + 1]
        cmp bh, 7
        jb AnswerNo
        cmp bh, 9
        ja AnswerNo

checkEqualSymb:

        mov bh, [Buffer + 5]
        cmp bh, [Buffer + 6]
        jne AnswerNo

checkFifthLetters:

        or byte [Buffer + 6], 32

        cmp byte [Buffer + 6], 'a'
        jl AnswerNo

        cmp byte [Buffer + 6], 'z'
        jg AnswerNo

checkNum:

        xor bh, bh
        mov bl, [Buffer + 1]
        sub bl, 2

        cmp byte[Buffer + bx], '0'
        jb AnswerNo

        cmp byte[Buffer + bx], '9'
        ja AnswerNo

AnswerYes:

        mov ah, 09h
        mov dx, Yes
        int 21h
        jmp Exit

AnswerNo:
        mov ah, 09h
        mov dx, No
        int 21h
Exit:
        mov ah, 08h
        int 21h

        ret

Condition:
        db "Enter your string (6 < length <= 9, 4th and 5th are equal, 5th - letter, symbol [length-3] - number ):$"

NewLine db 13, 10, 24h
No      db "NO$"
Yes     db "YES$"
Buffer  db 10, 0, 10 dup(?)