[Open-graphics] Multipliers in oga1hq

[Timothy Normand Miller]

On 9/3/07, Patrick McNamara <wpmcnamara at yahoo.com> wrote:
> Timothy Normand Miller wrote:
> > Well, that's not a bad idea. It's also worth pondering architectures
> > that have 512 local registers, unifying the scratch space with the
> > register file.  But that may be too radical.
> >
> This is pretty common in micro controllers.    In the 8 bit AVR series,
> there are 32 registers that are the low 32 bytes of the memory space.
> Same goes for the 8051 series, though the 8051 also supports a
> completely separate external memory space as well.  Personally, I think
> make perfect sense to not distinguish between the register set, scratch
> memory, and I/O space.  It reduces the number of instruction types,
> reduces the amount of decode logic, etc.
>
> While we obvious want to make the controller as easily programmable as
> possible, efficiency in execution and efficiency in implementation take
> precedence in my mind.

Can you give a little more detail on what you're envisioning here?
The advantage to a REG-REG architecture is that the instructions are
simple and fixed-size.  Mapping registers into the memory space has
some interesting theoretical advantages, but now you need more logic
to distinguish, and you lose some of the benefits of the way a RISC
processor is pipelined.

-- 
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Open Graphics Project