If you want to play with the hardware you need to be a driver. Otherwise any user program can hang or crash the system. Like back in the Windows 3.1 days.
There are drivers around to let you play with the printer port. But you can not hold the system to control the timing. serial or parallel. Preemptive multitasking. You can do things in increments of system clock ticks. But, the timing may not be very solid.

DOS may still run on a newer system. Unless it is too fast. but I guess you could clock it down.

Other wise write a program for a micro to do it.