min

sseq segment stack
b db 256 dup(?)
sseq ends

dseq segment
mass db 13,2,78,-78,0
len db 5
dseq ends

cseq segment
start: assume cs:cseq, ds:dseq, ss: sseq
    mov ax, dseq
    mov ds, ax

    mov cx, offset len
    mov ax, -127
    mov bx, 0
l:
    mov dl, mass[bx]
    mov dh, 0
    cmp dl, al
    jl ok
    mov ax, dx
ok:
    inc bx
    loop l

    mov ax,4C00h
    int 21h

cseq ends
end start