Cirrus Logic KM1120001002 56K ISA Modem Card Rev X2 Internal Dial-Up V.90

Cirrus Logic KM1120001002 56K ISA Modem Card Rev X2 Internal Dial-Up V.90

The Cirrus Logic KM1120001002 is a 56K internal ISA dial-up modem card designed for desktop PCs equipped with ISA (Industry Standard Architecture) expansion slots. Running at up to 56 Kbps and built around the Cirrus Logic modem controller chipset, this card provides standard POTS (plain old telephone service) dial-up connectivity via a pair of RJ-11 jacks on the bracket — one for the phone line and one for a pass-through handset. Two 3.5mm audio jacks on the bracket allow direct connection of speakers and a microphone for voice modem functions. The board carries the GT-97032 GENTO isolation transformer and is marked Rev X2 with part number KM1120001002 visible on the PCB silkscreen.

Specifications & What's Included

• Manufacturer: Cirrus Logic
• Part Number / MPN: KM1120001002
• Hardware Revision: Rev X2
• Bus Interface: ISA (Industry Standard Architecture)
• Maximum Data Rate: 56 Kbps
• Modem Standard: V.90
• Controller Chipset: Cirrus Logic
• Isolation Transformer: GT-97032 GENTO
• Line Connectors: 2x RJ-11 (telephone line + phone pass-through)
• Audio Jacks: 2x 3.5mm on bracket (speaker / microphone)
• FCC Compliance: Tested to comply with FCC standards for home or office use
• Form Factor: ISA half-height card with full-height bracket
• Included: Card only — no software, drivers, or accessories

Applications

ISA internal modem cards like the KM1120001002 were standard equipment in desktop PCs throughout the mid-to-late 1990s and into the early 2000s, when dial-up internet access over the public switched telephone network (PSTN) was the dominant form of home and small-office connectivity. The ISA bus was the prevailing expansion standard in IBM-compatible PCs of that era — found in systems running DOS, Windows 3.x, Windows 95, Windows 98, Windows NT, and Windows 2000. This card communicates directly with the CPU over the ISA bus and interfaces with the telephone line through its RJ-11 connectors, modulating and demodulating digital data into audio tones the phone network can carry. The 56K V.90 standard, which this card supports, was the final and fastest generation of dial-up modem technology before broadband became widespread. Today, ISA modem cards like this one are sought by collectors and hobbyists maintaining vintage or retro PC builds, as well as technicians supporting legacy industrial or embedded systems that still rely on ISA-bus hardware and dial-up or POTS-based communication links.