（1）
（2）
（3）汇编代码如下
assume cs:code,ds:data,es:table
data segment
db 'welcome to masm!'
data ends
table segment
dw 4000 dup (0)
table ends
code segment
start: mov ax,data
mov ds,ax
mov ax,0b800h
mov es,ax
mov bx,0
mov si,0
mov cx,16
s0: mov ax,[bx]
mov es:[bx+720h][si],ax
mov al,2
mov es:[bx+721h][si],al
inc bx
inc si
loop s0
mov bx,0
mov cx,16
mov si,160
s1: mov ax,[bx]
mov es:[bx+720h][si],ax
mov al,36
mov es:[bx+721h][si],al
inc bx
inc si
loop s1
mov bx,0
mov cx,16
mov si,320
s2: mov ax,[bx]
mov es:[bx+720h][si],ax
mov al,113
mov es:[bx+721h][si],al
inc bx
inc si
loop s2
mov ax,4c00h
int 21h
code ends
end start
