The unit must be connected to a dedicated serial port (either 9 or 25 pin) on your computer that is free of COM port and Interrupt (IRQ) conflicts. It is not required that the serial port reside on any particular COM number or IRQ value. This is important only to application software that you may be running in conjunction with the unit. The requirements for computer CPU speed, disk drive space, memory, and operating system are determined by the software application you are running.