Where keystrokes go ...
Press a key on today's PC, and you'll generate a hardware interrupt. Your system's BIOS contains some tiny bit of code which will record your keypress into buffer in RAM. (It will also translate this keypress into the appropriate character.) When finished, control will be returned to whatever was happening prior to the interrupt (keypress).
Now, the record of the keypress is in RAM. Some program, either operating system or application, will/may use or expect user action, and will take appropriate action. Here's where the water gets milky --- some operating systems use virtual memory, which is essentially a disk file containing data held in RAM. This data MAY contain the results of your keypress, or it may not: It depends on too many factors to predict with confidence.
However, in many cases, programs store user input for their own use. Typically, a word processor stores text, which is simply a series of characters, each entered with a keypress(or mouseclick). Continuing with the word processor example, the WP may feature periodic, timed, work saving, where the data is written to disk automatically, or the user is reminded to save the work manually, or, in rare cases, the user remembers to save the work without reminders.
Eventually, the user may decide to store the finished work permanently on disk. Until stored, the data is exposed to the dangers of loss; either accidental or inadvertently: Stupidity being more common than electrical outages.
It is also quite common for a system to take an action based on a keypress or mouseclick. In this case, there is no reason to store the value of this click beyond deciding what response to take. Keypresses used in this sense are the least likely to be stored on disk, or anywhere else.
You mentioned credit card use. Credit card numbers would probably not be quickly discarded by your system, but on the other hand, most likely should be. It all depends on what the developer had in mind when your system was coded. You could imagine the variety of possibilities match the vast array of programming practices found worldwide.
Enjoy the day, F.D. |
