Logitech C7-3F-9F Serial 3-Button Ball Mouse DB9 RS-232 COM Port Vintage PC

Logitech C7-3F-9F Serial 3-Button Ball Mouse DB9 RS-232 COM Port Vintage PC

The Logitech C7-3F-9F is a three-button mechanical ball mouse designed for RS-232 serial port connections. It connects via a DB-9 (9-pin D-sub) female serial connector and communicates over a standard RS-232 COM port, making it compatible with DOS-era and early Windows PCs equipped with a serial port. Made in the USA by Logitech, the C7-3F-9F carries FCC ID DZL6QBC and bears the UL mark.

Specifications & What's Included

• Manufacturer: Logitech
• Model: C7-3F-9F
• FCC ID: DZL6QBC
• Country of Manufacture: USA
• Number of Buttons: 3 (three square tactile buttons on top surface)
• Tracking Technology: Mechanical ball (rubber ball + tracking wheel assembly)
• Interface: Serial RS-232
• Connector: DB-9 female (9-pin D-Sub)
• Connection: Wired — attached cable with DB-9 serial connector
• Color: Beige/cream
• Design credited to: A. Cahen (Patent Pending per label)
• Includes: Mouse with attached serial cable only — no additional accessories

Applications

Serial ball mice like the Logitech C7-3F-9F were standard pointing devices for IBM PC-compatible computers throughout the late 1980s and into the 1990s, before PS/2 and USB interfaces became dominant. They connect to the 9-pin or 25-pin RS-232 serial (COM) port found on PC/XT, PC/AT, and 286/386/486-class machines, and communicate using the Microsoft or Logitech serial mouse protocol. The three-button layout was particularly valued in CAD, technical, and Unix-on-PC applications where a middle button or chord commands were used. Today these mice remain sought after for retro computing, vintage machine restoration, and legacy industrial or scientific systems that still rely on a working serial port and do not support USB input devices. They can also be used with modern systems via a USB-to-serial adapter, provided the appropriate serial mouse driver is loaded.