Some Eastern European, Arabic and Asian computers used other hardware code pages, and MS-DOS was able to switch between them at runtime with commands like KEYB, CHCP or MODE. In most cases typing a number greater than 255 produced the remainder after the number is divided by 256. Some would interpret the code as a command, but often it would be interpreted as a code to be placed on the screen at the location of the cursor, thus displaying the corresponding 8-bit character from the current code page. Applications reading keystrokes from the BIOS would behave according to what action they associate with that code. It would place the corresponding code into the keyboard buffer so that it would look (almost) as if the code had been entered by a single keystroke.
On IBM PC compatible personal computers from the 1980s, the BIOS allowed the user to hold down the Alt key and type a decimal number on the keypad.
