Questions about the DSP on the 4D/35...

[Bruce Karsh]

In article rpaul at crow.UUCP (Rodian Paul) writes:

>Hi, perhaps these questions are a little premature, but how are we going to be 
>able to access the DSP in our 4D/35's? 
>Will there be some kind of microcode compiler being released for it, or is SGI
>going to supply some front-end libraries?

The audio system, like our graphics systems, is accessed through a procedure
call library, the AL.  There's no microcode compiler.

>I'm not much up on DSP technology, but I seem to recall in a review I read
>when the NeXT first came out that their DSP (same 56000 series I believe) 
>can also be used to manipulate video signals. Will we be able to do this with 
>the 35's? How about dumping our our Image-Processing kernels down etc.

The DSP is not used to manipulate video signals.  The 56001 is pretty slow
for that, doesn't have much memory on it (32K words) and it's pretty much
used up just handling audio.  The MIPS processor and graphics are much faster
for manipulating video.

The DSP is used to handle the very high data rates of digital audio I/O
(up to 192,000 samples per second) without loading down the CPU.  With
the DSP, audio I/O can occur with no kernel intervention at all.

			Bruce Karsh
			karsh at sgi.com