IBM 16F0487 Token Ring Network Adapter Short ISA Card PC AT XT

IBM 16F0487 Token Ring Network Adapter Short ISA Card PC AT XT

The IBM 16F0487 is a short-form ISA Token Ring Network Adapter designed for connecting IBM PC AT, PC XT, and compatible ISA-bus computers to a Token Ring LAN. It uses a DB9 connector on the bracket for attachment to Token Ring cabling (typically via a media filter or MAU — Multistation Access Unit), and fits in a standard short ISA slot. The card is manufactured in Canada and bears a PCB date code indicating manufacture in 1991.

Specifications & What's Included

• Manufacturer: IBM
• Part Number / MPN: 16F0487
• PCB Revision: A (silkscreened on board)
• PCB Date Code: 91 8 926 (1991)
• Bus Interface: ISA (Industry Standard Architecture) — short card form factor
• Network Standard: Token Ring (IEEE 802.5)
• Bracket Connector: DB9 (9-pin) — standard Token Ring attachment connector
• Form Factor: Short ISA card
• Country of Manufacture: Canada (per FCC label on bracket)
• Visible ICs: Multiple Texas Instruments logic/memory ICs, oscillator crystal, DIP switch bank, and assorted support chips
• Includes: Card only — no cables, media filter, drivers, or documentation

Applications

Token Ring was IBM's proprietary LAN technology introduced in the mid-1980s, operating at 4 Mbps or 16 Mbps, and was the dominant networking standard in IBM-centric corporate environments through the early 1990s. Unlike Ethernet's bus/star topology, Token Ring used a logical ring where a token was passed sequentially between nodes, providing deterministic access and collision-free operation. Adapters like the 16F0487 were used to connect IBM PS/2 machines, PC ATs, and compatible ISA-bus computers to Token Ring networks via a Multistation Access Unit (MAU or MSAU) using shielded twisted-pair cabling with DB9 connectors or UTP with RJ-45 media filters. IBM's AS/400, System/36, and mainframe-connected environments relied heavily on Token Ring infrastructure throughout the late 1980s and 1990s. While Token Ring was largely displaced by Fast Ethernet by the late 1990s, these adapters remain sought after by vintage computing collectors, retro IBM PC enthusiasts, and anyone maintaining legacy IBM LAN environments or museum-grade hardware setups.