IBM 79G3688 Auto 16/4 Token Ring ISA Adapter 16-Bit 172885-001 Compaq

IBM 79G3688 Auto 16/4 Token Ring ISA Adapter 16-Bit 172885-001 Compaq

The IBM 79G3688 is an Auto 16/4 Token Ring network adapter for the 16-bit ISA bus. It auto-negotiates between 4 Mbps and 16 Mbps Token Ring speeds and connects to a Token Ring network via a single RJ-45 port on the metal bracket. The card is also cross-referenced under Compaq Assembly number 172141-002 and Compaq Spares part number 172885-001, making it a compatible replacement for Compaq ISA-bus systems as well as IBM platforms.

Specifications & What's Included

• Brand: IBM
• Model / FRU: 79G3688
• Manufacturer Part Number: 172885-001
• Compaq Assembly Number: 172141-002
• Compaq Spares Number: 172885-001
• Secondary FRU: 6787505
• Bus Interface: 16-bit ISA
• Network Technology: Token Ring, Auto 16/4 Mbps
• Port: Single RJ-45 connector on rear bracket
• Speed Label on Bracket: 16/4 (auto-sensing)
• Form Factor: Half-length ISA expansion card
• Card only — no drivers, software, or accessories included

Applications

Token Ring was IBM's LAN technology, introduced in the mid-1980s and standardized under IEEE 802.5. Unlike Ethernet's contention-based access, Token Ring used a deterministic token-passing scheme on a logical ring topology, which gave it predictable latency — a quality IBM marketed heavily to enterprise customers. Running at either 4 Mbps or 16 Mbps, Token Ring was widely deployed in IBM mainframe and midrange environments through the late 1980s and 1990s, connecting PCs, AS/400 terminals, and workstations to corporate LANs. ISA-bus Token Ring adapters like this one were standard in IBM PS/2 and compatible desktop PCs of that era. By the late 1990s and early 2000s, Fast Ethernet had displaced Token Ring in most new deployments, but many large enterprises continued running Token Ring infrastructure for years afterward. Today these cards are sought by administrators maintaining legacy Token Ring segments and by collectors preserving IBM PC-era hardware.