At 11:00 PM 8/6/96 -0700, Bill Stewart wrote:
At 11:34 PM 8/5/96 -0800, you wrote:
What is unclear, however, is WHY they "had to" build a card that couldn't do full-duplex. I mean, would there have been a problem implementing that? Or was this just another one of those stupid design decisions which could have been easily fixed if it had been realized in time?
2) DSPs tend to be really tight on resources, especially RAM, which you need to do multiple programs at once. $5-10 DSPs are especially tight. They're starting to come with mini operating systems.
I wasn't aware that sound cards made appreciable use of DSP's. Unlike modems, which inherently must massage large amounts of signal to get the data, I assumed that sound cards were more like straight A/D/A systems.
It also has the advantage that the data is being moved through your CPU, so encryption is an easy add-on, rather than having one combined modem/voiceblaster card which doesn't have any hooks for crypto or other processing. Well, I assume that if implemented as a new type of modem card, the processor can be used to do the data transfer.
If you're doing the voice crunching and A/D conversion and telephony all on the modem card, with everything tightly integrated to fit in your tiny cache, why put in hooks for the processor to intervene?
You'd put in a hook because it would be easily done, and to fail to do so would be a serious mistake. It could also be bypassed by a hardware switch, I suppose, or a software-controlled switch, to make processor intervention unnecessary. Jim Bell jimbell@pacifier.com