What is self testing?

Answer 1

It's where the printer will go through it's diagnostics and check the print head to make sure the heads aren't clogged and will basically go through the "motions" of printing a page to make sure the drive mechanisms, paper drive, etc, work ok.

Answer 2

Most electronic devices have been designed to run a self-test when first turned on. They take a look at their internal condition looking for problems.

The next thing that might happen is a test of any other devices that might be attached to them - ensure that those devices have a good line of communication, and they themselves are not reporting any problems.

The best example of course is a computer - the 'motherboard' executes a POST (post on self test) that is extensive in what it is looking at: internal routes of communication such as the norht & south bridges, integrated functions such as sound chipsets, cpu, power supply, attached hard drives / dvd-drives, keyboard, network interface cards, video, etc etc. And most of those devices, notably the hard drive(s) have conducted their own self-test.

If the device finds any problems during the self test, there will be a error code presented - such as the dreaded beeping w/ a black screen from a computer(!) - count the beeps to determine what the problem is... Arrrgh... Bad memories ;(