assume cs:code,ds:data
data segment
	db 'BaSiC'
	db 'InfoMaTion'
data ends
;------------------------------------
;做法一
code segment
start:	        mov ax,data
		mov ds,ax
		mov bx,0	;設(shè)置ds:bx指向數(shù)據(jù)段		
		mov cx,5	;對(duì)于第一個(gè)字符串進(jìn)行循環(huán)轉(zhuǎn)換
s:		mov al,ds:[bx]
		and al,11011111B  ;將字符的第五位轉(zhuǎn)換成0，轉(zhuǎn)換成大寫字母
		mov ds:[bx],al
		inc bx
		loop s 
		mov bx,5	;指向第二個(gè)字符串
 		mov cx,11
s0：		mov al,ds:[bx]
		or al,00100000B	  ;將字符的第五位轉(zhuǎn)換成1，轉(zhuǎn)換成小寫字母
		mov ds:[bx],al
		inc bx
		loop s 
		mov ax,4c00h
		int 21h
code ends
;------------------------------------
;做法二，改進(jìn)版：利用bx+idata實(shí)現(xiàn)代碼的簡(jiǎn)化
 
code segment
start:	        mov ax,data
		mov ds,ax
		mov bx,0
		mov cx,5
s:		mov al,ds:[bx]
		and al,11011111b
		mov ds:[bx],al
		mov al,ds:[bx+5]
		or al,00100000b
		mov ds:[bx+5],al
		inc bx
		loop s 
code ends
;------------------------------------
end start

assume cs:code,ds:data
data segment
	db '1. file         '
	db '2. edit         '
	db '3. search       '
data ends
code segment
start:	        mov ax,data
		mov ds,ax
		mov bx,0	;ds:bx指定數(shù)據(jù)段，同時(shí)bx作為定義行的變量 
		mov cx,3
s:		mov al,ds:[bx+3]	;3作為常量，定義第一個(gè)字母
		and al,11011111b
		mov ds:[bx+3],al
		add bx,16
		loop s 
		mov ax,4c00h
		int 21h
code ends
 
end

assume cs:code,ds:data,ss:stack
data segment
	db 'ibm             '
	db 'dec             '
	db 'vax             '
data ends 
;--------------------------------------------
;做法一
code segment
start:	        mov ax,data
		mov ds,ax
		mov bx,0 
		mov cx,3
s0:		mov dx,cx	;同時(shí)使用同一個(gè)變量進(jìn)行循環(huán)，需要對(duì)外層循環(huán)的值保存
		mov si,0
		mov cx,3	;cx設(shè)置成內(nèi)層循環(huán)的次數(shù) 
s:		mov al,ds:[bx+si]
		and al,11011111b
		mov ds:[bx+si],al
		inc si		
		loop s
 		add bx,16
		mov cx,dx	;用dx中存放的外層循環(huán)恢復(fù)外層循環(huán)的計(jì)數(shù)器
		loop s0
 		mov ax,4c00h
		int 21h
code ends 
;--------------------------------------------
;做法二，利用棧保存外層循環(huán)的值
stack segment
	dw 8 dup(0)		;利用棧段保存cx的值
stack ends
code segment
start:	        mov ax,stack
		mov ss,ax
		mov sp,16	;ss:sp指向棧段 
		mov ax,data
		mov ds,ax
		mov bx,0	;ds:bx指向數(shù)據(jù)段
 		mov cx,3
s0:		push cx
		mov si,0
		mov cx,3 
s:		mov al,ds:[bx+si]
		and al,11011111b
		mov ds:[bx+si],al
		inc si
		loop s 
		add bx,16
		pop cx
		loop s0
 		mov ax,4c00h
		int 21h
code ends
;-------------------------------------------- 
end start

assume cs:code,ds:data,ss:stack
data segment
	db '1. display      '
	db '2. brows        '
	db '3. replace      '
data ends
stack segment
	dw 8 dup(0)
stack ends 
code segment
start:	        mov ax,stack
		mov ss,ax
		mov sp,16 
		mov ax,data
		mov ds,ax
		mov bx,0 
		mov cx 3	;設(shè)置外層循環(huán)只有3行
s0:		push cx
		mov si,0
		mov cx,4	;設(shè)置內(nèi)層循環(huán)只需4次 
s:		mov al,ds:[bx+si+3]		;設(shè)置需要改變的第一個(gè)字母
		and al,11011111b
		mov ds:[bx+si+3],al
		inc si
		loop s 
		add bx,16
		pop cx
		loop s0 
		mov ax,4c00h
		int 21h
code ends
 
end start

assume cs:code,ds:data
data segment
	db 'conversation'
data ends
 
code segment
start:	                mov ax,data
		        mov ds,ax
		        mov si,0		;ds:si指向字符串所在空間的首地址
		        mov cx,12		;cx存放字符串的長(zhǎng)度
		        call capital
		        mov ax,4c00h
		        int 21h
 
capital:	        and byte ptr ds:[si],11011111b
			inc si
			loop capital
			ret
code ends
 
end start

assume cs:code,ds:data
data segment
	db 'conversation',0
data ends 
code segment
start:		        mov ax,data
			mov ds,ax
			mov si,0			;ds:si指向數(shù)據(jù)段的開始處 
			call capital
 			mov ax,4c00h
			int 21h 
capital:	        mov cl,ds:[si]		
			mov ch,0
			jcxz ok				;如果字符串為0，則會(huì)跳出循環(huán)
			and byte ptr ds:[si],11011111b
			inc si
			jmp short capital	        ;跳轉(zhuǎn)實(shí)現(xiàn)循環(huán) 
ok:			ret				;結(jié)束循環(huán) 
code ends
end start

assume cs:code,ds:data,ss:stack
data segment
	db 'word',0
	db 'unix',0
	db 'wind',0
data ends
stack segment
	db 8 dup(0)
stack ends 
code segment
start:		        mov ax,data
			mov ds,ax
			mov bx,0 
			mov cx,3		;外循環(huán)實(shí)現(xiàn)
s:			mov si,bx
			call capital
			add bx,5		;內(nèi)循環(huán)的實(shí)現(xiàn)
			loop s 
			mov ax,4c00h
			int 21h 
capital:	        push cx
			push si 
change:		        mov cl,ds:[si]
			mov ch,0
			jcxz ok
			and byte ptr ds:[si],11011111b
			inc si
			jmp short change 
ok:			pop si
			pop cx
			ret 
code ends
end