Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site l5.uucp Path: utzoo!linus!decvax!decwrl!sun!l5!gnu From: gnu@l5.uucp (John Gilmore) Newsgroups: net.micro.68k Subject: Re: Memory reads and writes... Message-ID: <169@l5.uucp> Date: Mon, 30-Sep-85 01:02:28 EDT Article-I.D.: l5.169 Posted: Mon Sep 30 01:02:28 1985 Date-Received: Wed, 2-Oct-85 21:10:51 EDT References: <436@puff.UUCP> Organization: Ell-Five [Consultants], San Francisco Lines: 13 In article <436@puff.UUCP>, wirch@puff.UUCP writes: > Can the 68000 read and write words on byte boundaries? The 68000 cannot access words or longwords on byte boundaries. The 68010 and 68012 cannot (same 68000 bus). The 68008 can (it has an 8-bit bus and no data alignment restrictions). The 68020 can (it has a 32-bit bus with dynamic bus sizing, and no data alignment restrictions.) The trap taken when you try this is "address error", which is very similar to "bus error". In fact, in the 68010 and 20, you can rerun it (useless) or supply data and go on from it (might be useful). It only occurs for instruction fetches in the 68008 and 68020.