TYAN InterServe 90 User Manual page 2

Errata
The System Board Manual from the manufacturer of the system board
reflects a wrong jumper setting for dual-floppy operation. In this
manual, jumper JP4 is listed as being open for dual-floppy support.
The correct setting is as follows:
JP4
Dual-floppy support
Single-floppy support
Pins 1-2
Closed
Open