“Assembly Language”, 3rd Edition by Wang Shuang
Chapter 14: Ports
Checkpoint 14.1 (Page 267)
(1) Program to read the content of cell 2 in CMOS RAM.
(2) Program to write 0 to cell 2 in CMOS RAM.
================Reference Answers(1) Reference code is as follows:
assume cs:codecode segment start: mov al, 2 ; Address and business data can only be placed in al or ax out 70H, al ; Send the address of the target storage cell through port 70H in al, 71H ; Read the data of cell 2 from port 71H into al
mov ax, 4c00H int 21Hcode endsend start (2) Reference code is as follows:
assume cs:codecode segment start: mov al, 2 ; First, place the address in al out 70H, al ; Send the address to port 70H mov al, 0 ; Place the data in al out 71H, al ; Send the data to port 71H
mov ax, 4c00H int 21Hcode endsend start