28 Jun
2013
28 Jun
'13
10:57 a.m.
On Fri, Jun 28, 2013 at 10:29 AM, Rob Doyle <radioengr at gmail.com> wrote:
Wasn't the original DEC Alpha missing 8-bit byte addressability and added
back later? Or something?
http://labs.hoffmanlabs.com/node/543
Classic Alpha processors ? all processors prior to EV56 ? and Alpha
system designs did not support byte and word addressing, which meant
access into I/O space involved ?swizzling?. Swizzling was a way of
allowing longword memory references to address the individual bytes
typically found in I/O space and with I/O controllers. A quantity of
host physical memory space was sparsely written, and effectively
compressed into a contiguous region of bytes by the I/O system.