IBM 25F7540 93F0198 MCA Token Ring 4MB Network Adapter Card PS/2

IBM 25F7540 93F0198 MCA Token Ring 4MB Network Adapter Card PS/2

The IBM 25F7540 is a Token Ring network adapter card designed for IBM PS/2 computers equipped with the Micro Channel Architecture (MCA) bus. It carries IBM FRU part number 25F7540 and board assembly part numbers 93F0198, 93F0198A, and 93F0198B. The card provides 4MB of on-board memory for Token Ring LAN connectivity and uses a DB9 connector on the I/O bracket for network attachment.

Specifications & What's Included

• IBM FRU: 25F7540
• Part Number: 93F0198 (also 93F0198A / 93F0198B)
• Bus Interface: MCA (Micro Channel Architecture)
• Network Technology: Token Ring
• On-Board Memory: 4MB
• Form Factor: Short MCA card with blue card guides/retainer
• I/O Connector: DB9 (standard Token Ring attachment)
• FCC Classification: Class A
• Board Revision visible on label: 2B84
• Card only — no cables, software, or documentation included

Applications

Token Ring was IBM's proprietary LAN technology, introduced in the mid-1980s as an alternative to Ethernet, and was a dominant networking standard through the late 1980s and into the 1990s, particularly in IBM and IBM-compatible enterprise environments. The MCA bus was introduced with the IBM PS/2 line in 1987 as a proprietary replacement for the ISA bus, offering faster data transfer and bus mastering capabilities. Token Ring adapters like the 25F7540 were used to connect PS/2 workstations to corporate Token Ring networks running at 4 Mbps or 16 Mbps, operating within IBM's Systems Network Architecture (SNA) environments and peer-to-peer LAN setups. Today this card is sought after for maintaining, restoring, or demonstrating legacy IBM PS/2 MCA systems, as well as by collectors of vintage IBM computing hardware from the late 1980s and early 1990s era.