Re: dsPIC33F Lua support (Was: Advocating Lua on an embedded systems fair)

[David Given <dg@...>]

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John Hind wrote:
[...]
> I am a fan of the 8-Bit PICs too having done projects using them, but always
> in assembler rather than C. I do not think they've made the 32-Bit
> transition well, either commercially or technically.

One idea I've been vaguely mulling over for a while is to emulate a
32-bit system on a 8-bit embedded processor.

While this does sound insane, and does have obvious performance issues,
it would allow really low pinout systems that would be stupidly cheap. A
bottom-end PIC could run the emulation in-core, and use a high-speed
serial interface to talk to a serial RAM chip; Microchip make 256kB
devices for under a dollar.

Of course, given that the low end PICs run at 4MHz or so and that
emulation overhead is *at least* an order of magnitude, you're probably
going to end up with a device roughly equivalent to a 500kHz real
processor. Even Lua might have trouble running at an acceptable speed on
that.

OTOH if you consider that your entire device is probably going to cost
about a dollar fifty, consist of two 8-pin DIP ICs, and consume about
3.5mA (most of which is the RAM!), the bounds for what makes
'acceptable' are really, really low.

- --
David Given
dg@cowlark.com
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