[stella] Chimera blog update

[Glenn Saunders]

For those of you who might be interested in Chimera
but aren't subscribed to my blog, I posted an update.

http://tinyurl.com/z36mu

Since it's impossible to run this on an emulator, and
static screenshots don't really tell you that much
anyway, I managed to get a video up of it running.

http://tinyurl.com/hvl82

For those who want to view the sourcecode just to see
how simple it is, I'm including it here.  The Chimera
header file gives you a good idea of how you code for
it.  The way the hotspots are arranged is still
subject to change if anyone has any good suggestions.

The main thing with the hotspots we've been trying to
do is to coopt as few addresses as possible and
require as few write operations as possible to get
work done, since Supercharger writes take a lot of
cycles.  For instance, when you are overwriting a
queue, you seek to the start index and you just
successively write.  It will index forward
automatically just as it does when you read.  Things
like that.  With peripherals, we're planning to just
expose a single input and output hotspot, and a
hotspot that lets you change the active peripheral ID.
 Ultimately it might be better to expose two I/O
channels to make it easier to stream data from an
incoming device to a separate output device.

What's taking up most of the hotspots are the queues,
naturally.  We have to reserve two hotspots for each
queue, the read/write one and the seek one.  We could
implement a single byte as a seek instruction window
in which you send messages through, like the ID of the
queue and the index, but that takes more CPU.  Some
useful effects may be possible by seeking queues in
mid-kernel, so at least some of the queues need to be
seekable with a single write.


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