Input/Output Instructions in Assembly Language
Input/output instructions in assembly language facilitate communication between the program and external devices, such as reading from or writing to files, displaying output, or receiving input.
Displays a string of characters to the output (e.g., console).
Reads a string of characters from the input (e.g., keyboard).
Displays an integer value to the output.
Reads an integer value from the input.
Open and Close Files
Opens and closes files for input/output operations.Example (Open):
How to use I/O instructions
To use I/O instructions in assembly language, the programmer must first identify the device that they want to communicate with. Once the device has been identified, the programmer can use the appropriate I/O instruction to read or write data to the device.
For example, the following assembly language instruction will read a character from the keyboard and store it in the register AL:
The in instruction is a generic I/O instruction that is used to read data from a device. The first operand of the in instruction is the register where the data will be stored. The second operand of the in instruction is the port address of the device. The port address is a unique identifier for the device.
To write a character to the monitor, the programmer can use the following assembly language instruction:
The out instruction is a generic I/O instruction that is used to write data to a device. The first operand of the out instruction is the port address of the device. The second operand of the out instruction is the register where the data to be written is stored.
Input/output instructions enable communication between a program and external devices, such as displaying output or reading input. These instructions, often involving syscalls and register manipulation, facilitate interactions with files, strings, integers, and other data sources in low-level programming.