<As an aside, there have been laser printer interfaces where the host <computer gets to control the laser engine control signals directly, <rather than talking to a 'formatter board' that turns <text/graphics/postscript/whatever into a suitable bitmap for printing. DEC LN03P (~1988), a video print engine. Used a bit map in the host computer wuth serializer, there is still a small embedded micro to cotrol the basinc mechanics. FYI: due to construction and process laser printers have to keep the paper moving or the image will be a mess. The most extreme was the LPS40 (DEC, 12/27/1997) that literally had a BA23 microvax in the base to do, networking, distributed queue management, Postscript to raster engine interpretation. It was then handed to a 4board set (bimaps and display list to raster bitmap engine) and set serially to the printengine. The printengine had 1 8085 to manage the system, 3 8749s to manage the mechanics and a 78pg11 to handle the large capacity paper input. All that was to print complex postscript pages at 40ppm. That seems obscene but starting one piece of A4 paper every 1.5 second plus between three and four peices in transit is not a trivial task. Then there was the Xerox 9700 (120ppm) monster (10+running feet of laser printer.). <Of course this is a slightly higher level than talking to the mechanics <directly, since you have a signal to tell the printer to start a page <rather than having to control the motor and clutches directly. But still, <the host computer has to monitor the Beam Detect signal and send suitably <timed pixels to the laser control input. Beam detect is a sync signal and it's all done in hardware. You get a sync and start DMAing data to a serializer at a preset clock rate. Not much different than driving a tube. <I've seen (and probably still have somewhere) plastic daisywheels with a <metal pin for the '.' , just to make the last a little longer when used <like this. My first plotter was a modified daisy mech, no daisy and a pin brazed to the solinoid. Good to 200 dpi or so. Allison