Diagnostic Wrap of an SDLC Adapter With a Single DMA Channel
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Diagnostic testing of a Synchronous Data Link Control (SDLC) Communication Adapter can be accomplished in both transit and receive operations with only one Direct Memory Access (DMA) channel. In a system with limited DMA resources, an SDLC communication adapter may have only one DMA channel available for both transmit and receive operations. This allows only half duplex operation and also poses a problem in testing the operation of the single DMA channel in diagnostic mode at rated speeds. The problem here is that wrapping transmit data to receive data does not fully test a single DMA channel since both memory read and memory write directions must be exercised.