If you still have an old computer, the problem is to connect to it modern mouse may be familiar to you. Old mechanical mouse, sooner or later
come into disrepair - cable wear, buttons do not work, etc. In general, modern laser mouse is usually much nicer than the devices of the last
Because the serial mouses are no longer produced, then the for PC without a PS/2 port is still two options: adapt the PS/2 or USB mouse.
With PS/2 mouse everything is much easier - this protocol can be implemented in almost any microcontroller, such as ATMega8.
The adapter is built on ATMega8 microcontroller and uses MAX232 to match the TTL signal levels with a serial port levels.
The microcontroller receives data from the PS/2 mouse and transmits them via the UART.