Oh boy, you guys are really making me feel old now. We used to screw around with this stuff some..

Basically it takes bitmap images of some form. IIRC correctly, you send it bytes, and it puts a dot if it gets a '1', and leaves a space if it gets a '0'. That's why the heads come in multiples of 8... You'd send it a byte at a time and it could fire up to eight heads at the ribbon. They have buffers big enough for one line, but the later ones could stop the print head halfway across a line and come back.

Contrary to what the youngbloods here say, the codes for it should be quite easy to find. The manuals usually have very detailed descriptions of how to put the printer into different printing modes (you have to switch to graphics mode, otherwise it interprets each byte as an ASCII character), and often how the printer accepts bytes. I realise you won't have a manual, but check the nostalgia sites on the web.

This is why postscript printers are soooo worth the money.

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Jeremy