- Option
- Optimize
- Optical scanner
- Optical disk
- Open architecture
- Open
- On-line service
- On-line help
- On-line
- On-board
- OLE/Object Linking and Embedding
- Offset
- Off-line
- Office automation
- OEM/Orginal Equipment Manufacturer
- Odd parity
- ODBC/Open DataBase Connectivity
- Octal
- OCR/Optical Character Recognition
- OOP/Object Oriented Programming
- Object oriented graphics
- Object oriented
- Object kode
- Object
- Numlock key
- Numeric keypad
- Null modem cable
- Null character
- NTSC/National Television Standards Comittee
- Not operator
- Z buffer
- Option key
- Os/2
- Outline font
- Output device
- Pad character
- Padding
- Page break
- PDL/Page Description Language
- Page down key
- Page printer
- Page up key
- Pagination
- Palette
- Paperless office
- Parallel
- Parallel interface
- Parallel port
- Parallel processing
- Parameter
- Parıty Checking
- Park
- Pascal
- Pathname
- PCI/Peripheral Component Interconnect
- PCL/Printer Control Language
- Abacus
- Abort
- A+
- Amiga
- Append