Introduction to Computer Systems (COE 251) - Levels of I/O Access and System Level Programming

These flashcards cover key terms and concepts in computer systems related to input/output access and system level programming.

Levels of Input-Output Access

Different tiers of communication between software and hardware, categorized from high-level programming to hardware communication.

High-Level Programming (HLL)

Languages such as C++ or Java that use functions for I/O operations, providing portability and convenience.

Operating System (OS)

Software that manages hardware resources and provides high-level functions for application programs.

Basic Input-Output System (BIOS)

A collection of low-level subroutines that facilitate communication between the operating system and hardware devices.

Application Programming Interface (API)

A set of functions and procedures allowing the creation of applications that access the features of an operating system or software.

Interrupts

Signals that allow external devices or processes to gain immediate attention from the CPU, crucial for high-priority processing.

Interrupt Service Routine (ISR)

A special program that executes in response to an interrupt, handling the required tasks.

Real-Address Mode

A 16-bit addressing mode with specific limitations, used by older operating systems like MS-DOS.

INT instruction

An assembly language command used to invoke an interrupt.

Interrupt Vector Table (IVT)

A data structure that holds addresses of interrupt handlers for each possible interrupt.

DOS Interrupt 21H

A set of functions provided by the MS-DOS Operating System for performing essential tasks such as input and output operations.

Function 09H of INT 21H

Used to display a string of text to the monitor, terminated by a dollar sign '$'.

Function 01H of INT 21H

Allows input of a single character from the keyboard with echo.

Function 07H of INT 21H

Allows input of a single character from the keyboard without echo.

Function 02H of INT 21H

Writes a single character to standard output.

Scroll Functions of INT 10H

INT 10H AH=06h scrolls the window up and AH=07h scrolls the window down.

Cursor Positioning with INT 10H

INT 10H allows setting the cursor position on the screen by specifying row and column values.