clear:汇编源码系列的clear
这个都是过去DOS时代
汇编源码
虽然已经过去了
但是对于学习汇编还是有帮助
汇编语言只是
员
门基础语言
大多人掌握即可
不
定要深入研究.......
name clear
page 55,132
title 'CLEAR --- control PC display'
;
; CLEAR Utility to clear display
; and 
character attributes
;
; Ray Duncan, Uncopyright (u) August 1983
; This program may be freely copied,
; mangled, enhanced, redistributed.
;
input equ 080h ;command line tail buffer
cr equ 0dh ;ASCII carriage 
;
cseg segment 
assume cs:cseg,ds:cseg
;
org 0100h ;since this will be
; a COM file
;
clear: ;initialize display...
;call BIOS video driver to
mov ah,15 ;get current display mode:
10h ;s AL = mode, and
;AH = no. of columns.
cmp al,7 ;
we are in graphics modes
je clear0 ;(modes 4,5,6) then exit
cmp al,3 ;but we are in mode 0-3
ja clear9 ;or 7 then continue.
clear0: ; up size of window to
;be initialized...
xor cx,cx ; upper left corner of
;window to (X,Y)=(0,0)
mov dh,24 ; Y to 24 for lower right
mov dl,ah ;corner, and X to the number
dec dl ;of columns ed by BIOS
;minus 1
mov bh,7 ;initialize attribute
;to "normal" video display,
;i.e. white _disibledevent=0
xor dx,dx
10h
;
clear9: 20h ;exit to PC-DOS
;
cseg ends
;
end clear
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