bits and butts

[Tom Jennings]

On Fri, 24 Dec 2004, Jim Battle wrote:

re: 9 bits
>   We doubled the
> peak throughput by adding only 12.5% more datapath resources.  The
> second reason was that the chip used RAMBUS memories, which were only sold
> with 9b channels, and we had no particular need for parity.

That's pretty clever, a good use for those parity RAMs! Two-wide
would make 18 bits, a really nice width (3 characters).

> The multipliers had various rounding modes, including "round random", where 6b
> pseudorandom bias was added just below the trucation point, as some audio
> filter algorithms have better spectral properties with this type of rounding.

Man, I love bizarre hardware solutions to problems like that. It
all sounds so baroque.