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Received: by minnie.vk1xwt.ampr.org with NNTP id AA1481 ; Tue, 23 Feb 93 14:43:23 EST Newsgroups: comp.unix.bsd Path: sserve!manuel.anu.edu.au!munnari.oz.au!uunet!hobbes!md From: md@sco.COM (Michael Davidson) Subject: Re: Will 386bsd run for Pentium machine without pain? Organization: The Santa Cruz Operation, Inc. Date: Mon, 15 Feb 1993 23:47:58 GMT Message-ID: <1993Feb15.234758.23855@sco.com> References: <44714@sdcc12.ucsd.edu> <78655@apple.apple.COM> <1993Feb12.042349.18579@netcom.com> <78672@apple.apple.COM> Sender: news@sco.com (News admin) Lines: 20 mg@Apple.COM (Mark Gorlinsky) writes: >In article <1993Feb12.042349.18579@netcom.com> hasty@netcom.com (Amancio Hasty Jr) writes: >>Question: does the pentium have memory block move instruction? >>This could be useful for doing bitmap block transfers to >>a vga card... >All of the iX86 cpus have memory block move instructions. The pentium is >part of this family and therefore has them too. However, even on a 486 it is theoretically faster to do a series of register loads and stores in an unrolled loop that moves, say, 16 or 32 bytes per iteration than it is to use the string move instruction with a repeat prefix. (I say "theoretically" because unless you are getting cache hits on everything there turns out to be little measureable difference in practice - certainly if you are really writing to a VGA card with an ISA bus interface the limiting factor is the speed of the card which is so *slow* that it hardly matters what kind of code you use to access it ...)