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Funny you should say that; I went from Tops-20 systems programming to embedded systems development for 4 or 5 years. If you Google the ProDisk-464, you can see the system I worked on.? I designed a high speed crash proof file system specifically for multi-channel audio recording in 1989 and worked on it until 91 or 92. The system had a time division multiplex bus which would allow up to 64 channels of audio, which nobody was doing in the digital realm, back then.? The audio was split up to storage units (or SU's) where my code ran.? Each SU could handle four channels of sound and was running my operating system in 80286 protected mode. Despite what Bill Gates says, I loved that processor.? It was finicky about selector usage and length and wrung a lot of bugs out.? The user interface was on a Mac, partly written in C. Sometimes to find bugs that, I would cross compile it and run it on the 286. Every so often, I had to tweak things into assembler to meet the real time requirements.? The only problem was an AMD 9516 DMA controller that we used.? It was very nice, being able to execute short channel programs.? This worked well almost all the time; in fact, it was pretty wonderful--a lot easier than an RH20. And along came the extreme cases; since it was reading its channel program from the same memory that was being DMA'd to, for very short transfers (like a few words), you could blow it completely and not get to the interrupt in time. Bad...? Very audible.? The solution really broke my heart; I had to toss all my fine interrupt and channel building code and sit in a tiny loop polling.? Ugh... Every time I think about getting back into embedded systems, I think about the 9516 and ... think about doing something else.