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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. 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.
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...
INT 10h is fairly slow, so many programs bypass this BIOS routine and access the display hardware directly. Setting the video mode, which is done infrequently, can be accomplished by using the BIOS, while drawing graphics on the screen in a game needs to be done quickly, so direct access to video RAM is more appropriate than making a BIOS call ...
In a computer, an interrupt request (or IRQ) is a hardware signal sent to the processor that temporarily stops a running program and allows a special program, an interrupt handler, to run instead. Hardware interrupts are used to handle events such as receiving data from a modem or network card , key presses, or mouse movements.
The IBM PC (BIOS and MS-DOS runtime) does not follow the official Intel layout beyond the first five exception vectors implemented in the original 8086. Interrupt 5 is already used for handling the Print Screen key, IRQ 0-7 is mapped to INT_NUM 0x08-0x0F, and BIOS is using most of the vectors in the 0x10-0x1F range as part of its API.
Dialing *70 can prevent the call from completing when the phone line does not have the call waiting feature active. Leave this option unchecked if you are no longer able to connect. 3. Check or uncheck, “I have to dial this number to reach an outside line” depending on your telephone line. Normally, this should not be selected.
Scancodes on IBM PC compatible computer keyboards are sets of 1 to 3 bytes which are sent by the keyboard. Most character keys have a single byte scancode; keys that perform special functions have 2-byte or 3-byte scancodes, usually beginning with the byte (in hexadecimal) E0, E1, or E2.
The Alt key on an Apple keyboard. Since the 1990s, Alt has been printed on the Option key on most Mac keyboards. As of 2017, the newest Apple keyboards do not contain the Alt label. Alt is used in non-Mac software, such as non-macOS Unix and Windows programs, but in macOS it is always referred to as the Option key.