Arnet MA-165-02 Rev.3 MultiPort-2 IBM PC ISA Serial I/O Card 8-Port RS-232

Arnet MA-165-02 Rev.3 MultiPort-2 IBM PC ISA Serial I/O Card 8-Port RS-232

The Arnet MA-165-02 MultiPort-2 is an 8-port asynchronous serial I/O expansion card designed for IBM PC, PC/XT, and PC/AT systems using the ISA bus. Produced in 1988, this card allowed a single ISA slot to support multiple RS-232 serial ports simultaneously — a critical capability for connecting multiple terminals, modems, printers, or serial peripherals to a single host machine. The board is marked Rev. 3 and carries the Arnet MultiPort-2 designation on the PCB silkscreen.

Specifications & What's Included

• Manufacturer: Arnet Corporation
• Model: MA-165-02
• Revision: Rev. 3 (printed on PCB)
• Product Line: MultiPort-2
• Bus Interface: ISA (Industry Standard Architecture) — full-length card
• Serial Interface: RS-232 asynchronous
• Number of Ports: 8
• External Connector: DB-25 female on bracket
• Logic ICs visible on PCB: SP8836, DM74LS138N, DM74LS02N (National Semiconductor/Signetics DIP packages)
• PAL devices: PAL16L8NC visible on PCB
• Form Factor: Full-length ISA expansion card with blue plastic card guides
• Year of Manufacture: 1988
• Compatible With: IBM PC, PC/XT, PC/AT, and ISA-bus compatible systems
• Included: Card only — no cables, driver software, or documentation

Applications

Multi-port serial I/O cards like the Arnet MultiPort-2 were a staple of 1980s PC-based computing, particularly in environments requiring connections to multiple RS-232 devices from a single host. Typical deployments included multi-user systems running multi-tasking operating systems such as UNIX, Xenix, or SCO, where each serial port served a separate terminal or dumb terminal session. They were also widely used in industrial automation and data acquisition environments, point-of-sale systems, and anywhere a PC needed to communicate with several serial instruments, barcode readers, or plotters simultaneously. Arnet was a well-regarded U.S. manufacturer of serial expansion hardware in the mid-to-late 1980s, competing with products from DigiBoard and Boca Research. ISA-bus serial cards of this type were largely superseded by PCI-based serial cards and USB-to-serial adapters through the 1990s, but systems requiring period-accurate ISA hardware for legacy software or retro computing still have genuine demand for these cards today.