跪求几个汇编程序的答案！高人进！

1：编程实现求S=（X^2+Y^2)/2的值，并将结果放入RESULT中
2：求出从1~100中所有的偶数
3：在数据段中有一个字节数组，编程统计其中正数个数放入A单元，负数放入B单元。
4：编写实现 计算函数值S=X/2（X<0) S=X/3 (0<=X<=20) S=X/4 (X>20)

第三题：
正数放在PLUS_BUF单元中，负数放在MINUS_BUF单元中

DATA SEGMENT
BLOCK DB 0BH,4BH,0F4H,0AFH,0AH,90H,87H,50H,0F4H,0F3H,21H
DB 99H,0FFH,40H,77H,88H,0B3H,9EH,06H,08H,02H,3AH,91H
CNT EQU $-BLOCK
PLUS_BUF DB CNT DUP(0)
MINUS_BUF DB CNT DUP(0)
STO1 DB 1 DUP(0)
STO2 DB 2 DUP(0)
STO3 DB 'The positive numbers are: $'
STO4 DB 'The negatives are: $'
STO5 DB 'The number of positive number is: $'
STO6 DB 'The number of negative is: $'
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA,ES:DATA
START:
MOV AX,DATA
MOV DS,AX
MOV ES,AX
MOV BX,0
MOV DX,0
LEA SI,BLOCK
LEA DI,PLUS_BUF
LEA BP,MINUS_BUF
MOV CX,CNT
CLD
NEXT:LODSB
TEST AL,80H
JNZ MINUS
STOSB
INC BL
JMP AGAIN
MINUS:XCHG BP,DI
STOSB
INC DL