General Interface Systems GIS 4-Port Data Switch DB25 Parallel Serial Selector

General Interface Systems GIS 4-Port Data Switch DB25 Parallel Serial Selector

This is a General Interface Systems, Inc. (GIS) 4-Port Manual Data Switch, a compact desktop device used to route data signals from a single host to one of four peripherals — or to share a single peripheral among multiple devices — by turning a rotary selector knob. No software, drivers, or power source are required; switching is fully mechanical and instantaneous. The unit uses DB25 (25-pin) connectors and is compatible with RS-232 serial and standard parallel interfaces common in legacy computing environments.

Specifications & What's Included

• Brand: General Interface Systems, Inc. (GIS)
• Type: Manual 4-Port Data Switch / Port Selector
• Number of Ports: 4 (selectable via front-panel rotary knobs)
• Connector Type: DB25, 25-pin — female connectors on rear panel
• Interface Compatibility: RS-232 serial, parallel (Centronics-compatible via DB25)
• Switching: Manual rotary selector knobs — no power required
• Form Factor: Desktop / freestanding enclosure
• Enclosure: Cream/off-white plastic housing
• Unit only — no cables included

Applications

Manual data switches like this GIS unit were standard tools in offices and small computer rooms from the late 1980s through the mid-1990s, when RS-232 serial ports and parallel printer ports were the dominant peripheral interfaces. They allowed a single computer to be connected to multiple printers, plotters, or other serial/parallel devices — or let multiple computers share a single printer — without physically swapping cables. GIS produced a range of these mechanical switch boxes for business and light industrial use. Today they remain useful in legacy computing and industrial environments where older RS-232 serial equipment (terminals, PLCs, instruments, barcode scanners, label printers) is still in service and cable-sharing or signal-routing between devices is needed without adding software overhead.