Work of scaner mostly depends on it's type - SCSI/LPT/USB/..., because TWAIN-interface is supported. Also you can find information about scanners and OS/2 here.
eComStation it's a reactive system, comfortable to use. 'Pre-emptive' multitasking + support of multi-processor/multi-core computers since 1994 + major part of programs are using Multi-threading.