"Michael S. Klein" wrote:
> 
> We dont need to get Squeak on printers, but right now, Squeak exists
> primarily on desktop machines, with PDA's coming in second.  I was
> just identifying printers as an interesting class of computers that
> *already* use a VM approach, that would be interesting to have Squeak
> on.
> 
> I have no idea of how easy it is to reprogram a printer (or a PDA, for
> that matter).

It is as easy or difficult as any other embedded application. IOW you
don't (usually) have a nice graphical front-end, or nice debugging
facilities, or anything else that's nice.
However, I have read some statements about printer programming, and I
gather from that source that they debug most stuff on an ordinary PC (or
maybe a workstation), simulating the actual print engine. "Most stuff"
probably being the printer language interpreter, memory management, the
rasterizing process, and similar things.
The hard real-time stuff is probably hairy (regardless of environment).
The printer has to respond to various events with a pretty quickly
(paper jam sensors, start-of-page sensor to kick off the imaging
process, we-have-to-prepare-another-raster-line timer(?) interrupt).
These real-time requirements absolutely disallow a stop-the-world
garbage collector - and I really hope Squeak has an incremental one!

There is nothing particularly difficult about building a VM on top of
the real-time stuff, though. It's done regularly for any PostScript
printer in the world, and despite appearances, PostScript is a full
Turing-equivalent programming language. IOW you write a Squeak VM in
PostScript and run Squeak VMs on a PostScript printer (not that the
result will be particularly useful, without a mouse and a screen display
- and you'll probably run into space limitations anyway).

> Does ghostscript run on any printers?

No (AFAIK).

> Or is this just another way of
> generating a bitmap to send to the laser printer.

Yes. It's also a way of generating a bitmap for a CRT, so you have some
added value as well :)

Regards,
Joachim
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