On Oct 24, 2008, at 3:29 AM, Wouter van Ooijen wrote:

> I certainly don't know any other CPU architecture that has indexed
> access to its registers!

DEC PDP-10; the registers were also addressable as the first 16
memory locations.  You could even put code in the registers and
jump to them, for a speed boost.

The "register vs ram" thing on PIC got particularly interesting
when comparing low-end PICs vs low-end AVRs, since the AVRs had
32 registers and 0 "ram", while the PIC had W and "less than 32"
"general purpose registers."

For that matter, the AVR registers also share an indexed address space  
with RAM.  The "indexed" space has "general purpose" registers from 0  
to 31, "IO registers" from 32 to 95, and "Ram" from 96 upward  
(at90s2313; exact values might differ.)

BillW

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