| Abkürzung | Bedeutung |
| AAD | Analog Alignment Diskette |
| ABC | Atanasoff-Berry Computer |
| ABE | Agent Building Environment |
| ABIOS | Advanced Basic Input/Output System |
| AC | Alternating Current |
| ACF | Advanced Communications Function |
| ACK | Acknowledgement |
| ACL | Access Control List |
| ACPI | Advanced Configuration and Power Interface |
| ACS | Automatic Class Selection |
| ADC | Analog Digital Converter |
| ADCCP | Advanced Data Communications Control Procedures |
| ADP | Automated Data Processing |
| ADPCM | Adoptive Differential Pulse Code Modulation |
| ADSC | Adobe Document Structuring Conventions |
| ADSI | Active Directory Services Interface |
| ADSL | Asymmetric Digital Subscriber Line |
| AF | Auxillary-Carry Flag |
| AFC | Automatic Frequency Control |
| AFP | AppleTalk File Protocol |
| AGC | Automatic Gain Control |
| AGIS | Apex Global Information Services |
| AGP | Accellerated Graphics Port |
| AI | Artificial Intelligence |
| AIN | Advanced Intelligent Network |
| AIX | Advanced Interactive Executive |
| AKM | Apogee Kick Motor |
| ALI | Acer Laboratories, Inc. |
| ALIVE | Artificial Life Interactive Video Environment |
| AMD | Advanced Micro Devices |
| AMI | Alternative Mark Inversion |
| AMI | American Megatrends, Inc. |
| AMS | Access Method Services |
| ANA | Automatic Number Announcement |
| ANI | Automatic Number Identification |
| ANSI | American National Standards Institute |
| AOL | America On-Line |
| APA | All Points Addressable |
| APC | American Power Conversion |
| API | Application Program Interface |
| APM | Advanced Power Management |
| APPC | Advanced Program-to-Program Communications |
| ARC | Attached Resources Computing |
| ARLL | Advanced Run Length Limited |
| ARP | Address Resolution Protocol |
| ARPA | Advanced Research Projects Agency |
| ARPANET | Advanced Research Projects Agency Network |
| ARQ | Automatic Repeat Request |
| AS | Autonomous System |
| ASAP | Any Service/Any Port |
| ASCII | American Standard Code for Information Interchange |
| ASG | Advanced Systems Group |
| ASIC | Application Specific Integrated Circuit |
| ASME | American Society of Mechanical Engineers |
| ASP | Association of Shareware Professionals |
| ASPI | Advanced SCSI Programming Interface |
| ASR | Automatic Send/Recieve |
| AST | Asynchronous Systems Trap |
| AT | Advanced Technology |
| AT | Attention |
| ATA | AT Attachment |
| ATAPI | AT Attachment Packet Interface |
| AT&T | American Telephone & Telegraph |
| ATM | Adobe Type Manager |
| ATM | Asynchonous Transfer Mode |
| AUI | Attachment Unit Interface |
| AVI | Audio/Video Interleaved |
| AVN | Ameritech Virtual Network |
| AWB | Aglets Workbench |
| AXP | Almost Exactly Prism |