IBM 90X9929 MCA Dual Serial Card Adapter 33F8702XM Async

IBM 90X9929 MCA Dual Serial Card Adapter 33F8702XM Async

This is a vintage Micro Channel Architecture (MCA) dual serial communication card from IBM, designed for PS/2 and compatible systems. The 90X9929 provided two asynchronous serial ports for connecting modems, printers, plotters, and other serial devices to IBM midrange computing platforms. MCA cards like this were standard expansion components in business computing environments throughout the late 1980s and early 1990s.

Specifications & What's Included

• Manufacturer: IBM
• Model: 90X9929 (33F8702XM)
• Type: MCA Dual Serial Async Card
• Interface: Micro Channel Architecture (MCA) slot connector
• Serial Ports: Dual DB-9 RS-232 asynchronous ports
• Compatible Systems: IBM PS/2, IBM PS/1, and MCA-equipped compatibles
• Form Factor: Full-length ISA/MCA expansion card
• Era: Late 1980s–early 1990s
• Condition: Inspected, cleaned, fully functional

Applications

This card was widely used in IBM PS/2 and compatible systems to expand serial connectivity for business applications. Typical uses included connecting external modems for dial-up networking, attaching serial printers and plotters for data output, and linking to legacy serial peripherals and industrial control devices. The dual-port design allowed simultaneous operation of two serial devices, making it essential in multi-peripheral office and technical environments. This is a recognizable artifact from the era when Micro Channel Architecture was IBM's standard expansion bus for PS/2 systems, before PCI became dominant in the mid-1990s. Collectors and retro-computing enthusiasts seek these cards to restore vintage IBM systems to full working condition.