Extended Function Adapter
Original Publication Date: 1979-Nov-01
Included in the Prior Art Database: 2005-Feb-20
This article describes an extended function adapter (EFA) which, in operation, attaches to the input/output (I/O) bus of a processor and may be utilized to perform a variety of functions, which will be described below, that allows an existing processor architecture to be expanded without processor redesign. In addition, it will allow an entry processor design to be expanded without expensive "hooks" in the processor. The adapter can be constructed in its entirety by hardware, or, alternatively, it may be constructed using a microprocessor with supporting microcode. The adapter using conventional techniques can access the processor storage via existing cycle steal or direct memory-access mechanisms.