Tony> I have an idea that at least one version had a very low-level Tony> interface. No internal formatter, there were signals on the Tony> interface to turn the laser on/off, a return signal to indicate Tony> when the beam was staring a scan across the drum, and so Tony> on. Somewhat similar to the CX-VDO interface. Tony> What is the connector on your printer. I think the low-level Tony> interface used a 50 way Microribbon connector. Not a laser printer but similar... I worked with a Versatec electrostatic printer (100 dpi or so) in 1976. It used a simple bitmap interface, you'd just feed it pixels one scan line at a time. It was hooked up to a Cyber 73. paul

Do you have any technical informaiton, particularly scheamtics of the Lilith interface? Having done battle with the PERQ laser printer interface (which was desigend to connect to a CX-VDO printer, alothough I believe it could be used with an LBP-10, maybe with minor modifications), and having converted an LBP-8A1 into a CX-VDO, I might well be ale to spot things on the schematic. -tony

Is the microcode commented source? If so, what (human) language are the comments in? I might recognise soemthing in the comments -- signal names, etc -- that will help to sort out the interface. -tony

OK, I'll take a look sometime, and see if I recognise anything. This does not suprise me. Rmemeber that with a laser printer, once you've started the page (got the paper moving, etc), you can't pause midway through. You have to keep on feeding data to the laser at the right rate. So either you have to build up the entire bitmap before you start the page, or be sure you can do so on the fly quickly enough. Some early stand-alone laser printers with limited RAM did the latter -- they didn't have enough RAM to store a full-page bitmap. So you couldn't print full-page graphics. Text could be turned from ASCII codes to bitmaps on the fly, ginen a itmapped font. But anyway... These early workstations obvious worked with bitmapped data in memory for the video display. In the case of the PERQ (which I am more familiar with), there was hardware and microcdoe to do bitmap updates. And it made sense ot use that for producing the printer bitmapped image, rather than to use spearare hardware in the printer itself. Hence the low-level interface. I can tell you a little about the CX-VDO interface, which may be somewhat simuilar. There's a bit-serial comamnd/status interface, which is used to do things like select the manual feeder, report errors (out of paper, etc). At firt you cna probably ignore this. There are 3 signals involved with starting a page. I forget the names, but basicalkly they work like this : 1) A signal from the cotnroller to the printer causes the printer to start the main drive motor and scanenr motor, and get the speed control PLLs locked. Then the paper pickup clutch is engaged and the top sheet of papepr is taken from the tray as far as the registration shutter 2) At this point the printer asserts a vertical synchronisation signal back to the controller. The cotnrol has to respond within a certain (short-ish) time, or the printer will time out with a paper jam (?) error 3) The controller asserts another signal. At this point the registration shutter opens, and the paper starts moving towards the drum. The controller waits a suitable time (actually counts Beam dectect pulses, I think) to skip the top margin, and then starts sending the bitmap, synchronsied by the beam detect pulses (which are sort of horizontal sync). Hoiw much of this is done in hardware, how much in microocde, etc, is down to the system. It's a great pity you don't have schematics of the Lilith interface. -tony

I beleive so. The Acorn Archimedes did too. As did the PERQ (I speak from experience in the last case..). AFAIK these wrre Canon CX-VDO printers -- basically a CX printer (think of the LBP-8A1, the HP Laserjet 1, rtc) without a formatter board, and with a DC37 socket wired to the input of the DC controller (Engine controller) PCB. A similar internface, mostly backwrds compatible, was avaialle for the SX printers (Laserjet II, etc). It was a PCB containing a few uffer chips that mounted in place of the formatter PCB. -tony