wirch@puff.UUCP (09/27/85)
This is really a simple question, but I'm not sure. I heard a rumor to this effect, and I couldn't verify it: Can the 68000 read and write words on byte boundaries?
gnu@l5.uucp (John Gilmore) (09/30/85)
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.
george@mnetor.UUCP (George Hart) (09/30/85)
In article <436@puff.UUCP> wirch@puff.UUCP writes: >This is really a simple question, but I'm not sure. I heard a rumor >to this effect, and I couldn't verify it: > >Can the 68000 read and write words on byte boundaries? Nope. Neither can the 68010 or 68008. But the 68020 can. -- Regards, George Hart, Computer X Canada Ltd. UUCP: {allegra|decvax|duke|floyd|linus|ihnp4}!utzoo!mnetor!george BELL: (416)475-8980