Path: utzoo!attcan!uunet!cs.utexas.edu!ut-emx!emx.utexas.edu!star2.cm.utexas.edu!david From: david@star2.cm.utexas.edu (David Sigeti) Newsgroups: comp.sys.intel Subject: Systems/motherboards using 486 burst mode? Message-ID: Date: 11 Dec 90 22:43:29 GMT Sender: news@ut-emx.uucp Organization: University of Texas at Austin Lines: 17 Does anyone out there know which manufacturers (if any) of 486 systems or motherboards actually use the 486 burst mode? In a recent review of 33MHz 486 systems in PC Magazine there was a cryptic comment about "lack of support for the burst mode of the 486" but there was no elaboration and no discussion of the issue in the individual reviews. For those who wonder what I am talking about, the burst mode is a fast way of filling a (128-bit) line in the 486's internal cache. Normally, a memory read requires two clock cycles. When the 486 is filling a cache line, however, it can accept successive (32-bit) reads in a single clock cycle each, if the surrounding circuitry supports it. Thus, filling a cache line can be accomplished in five clock cycles (one to assert the starting address plus one for each 32-bit read) rather than eight clock cycles (two for each 32-bit read). -- David Sigeti david@star2.cm.utexas.edu cmhl265@hermes.chpc.utexas.edu