[windows]uninstall TCP/IP stack

Yestoday, my classmate's laptop is inspection. after cleaned the
virus. TCP/IP stack is broken

when i run ipconfig , it output nothing.

I decide to uninstall TCP/IP, then Google & Baidu.

the method is

change 0xa0 to 0x80 in the file "%windir%\inf\nettcpip.inf"

[MCU]exchange in PIC

Today, the teacher ask us to implenting exchanging the contents of two
file without use third-party file register.

Then, this is my answer

movf a, w
xorwf b, w
xorwf a, f
xorwf b, f

to proof

A xor B = C
C xor A = B
C xor B = A