Anton Aylward wrote:
John Andersen said the following on 01/14/2012 03:45 PM:
But not all applications have that need, and lots of things work just fine with smaller registers. For example, most loops are just fine with 8-bit registers ...
I suspect, that somewhere in the history of computing, there have been machines with small registers dedicated to loop counting. After all, its a much simple operation than having a general purpose register that can handle arithmetic and shift etc, and back in the days of valves all that logic was expensive.
I have worked at the machine level on several types of CPU and never seen such a "loop counter". On the other hand, a general purpose register that could handle that function, among many others has been part of every one and would be essential in any useful computer, unless all operations were performed in memory. BTW, the Data General Nova & Eclipse computers had an interesting feature called autoincrement (and decrement) memory. When memory was indirectly accessed through one of those autoincrement or decrement locations, the number they contained was incremented (or decremented). This was useful when you had to access sequential memory locatings. Those computers also had four accumulators, which were general registers that could do arithmentic and logic functions. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org