What Is a Bus Mouse? A Technical History of Early Microsoft Mouse Interfaces
2 days ago
- #Input Devices
- #Microsoft
- #Vintage Computing
- The term 'bus mouse' originated with Microsoft in the early 1980s, referring to specific connectors and pinouts.
- The original Microsoft Mouse (1983), known as the 'green-eyed mouse', was a bus mouse with a male DE-9 connector and 100 CPI resolution.
- A serial version with an RS-232 interface and female DB-25 connector was released in 1984.
- The bus mouse included an ISA card with a DE-9 female connector and an Intel 8255 Programmable Peripheral Interface (PPA) chip.
- Quadrature encoding was used to determine mouse movement direction and speed via phase differences in signals.
- Microsoft's second-generation mouse (1985) featured grey buttons, 200 CPI resolution, and retained the DE-9 bus mouse version.
- In 1986, Microsoft introduced the InPort interface with a Mini-DIN-9 connector, requiring +5V power for optical encoders.
- The PS/2 mouse standard (1987) replaced the bus mouse with a synchronous serial protocol via a Mini-DIN-6 connector.
- NEC PC-98 computers used a pin-compatible, 8255-based design similar to the Microsoft bus mouse.
- Various platforms like Atari ST, Commodore Amiga, and Acorn used similar quadrature signals but with different connectors and pinouts.
- Early Microsoft mice, especially the 'green-eyed' version, are now valuable collectibles.