Help-Bus Errors

[John Macdonald]

Wow, a chance to pick nits on Chris Torek...

In article <22598 at mimsy.umd.edu> chris at mimsy.umd.edu (Chris Torek) writes:
| In article <1990Feb10.192028.16025 at eddie.mit.edu> aryeh at eddie.mit.edu
| (Aryeh M. Weiss) writes:
| [lots of good stuff]
| >SIGBUS errors are quite machine dependent ... [but include, e.g.,]
| >reference an odd address with a word oriented instruction ... on Vaxes
| >and 68000's ....
| 
| As someone else already mentioned, VAXen do not care about address
| alignment except for speed (aligned operands are somewhat faster).
| 68000 and 68010 CPUs do; 68020 and 68030 CPUs do not;  [ ... ]
                           ^^^^^

On the 68020, only data references can be unaligned (and slow); code words
must have even alignment or the fetch fails.  I would guess that the 68030
is the same, but I've never checked.
-- 
Algol 60 was an improvment on most           | John Macdonald
of its successors - C.A.R. Hoare             |   jmm at eci386