Apple LaserWriters and HP LaserJets

I am not laserjet cerrtified (or anything-else certified for that matter), but let me tell you a little story... Over 10 years ago I was given a broken Canon LBP8-A1 printer. This is actually the same as an LJ1 with different ROMs (HP used the Canon formatter board in the LJ1). Well, it didn't take me long, even then, to find a dead HAL (mask-programmed version of a PAL) chip on the formatter board. Canon, of course were totally unhelpful. No replacement chips, not even a replacement board (I didn't know about The PrinterWorks back then). But I had a PERQ, and I remmebered reading somewhere on Usenet that the PERQ had an optional laserprinter controller board that talked to a thing called a CX-VDO (which I'd never heard of). incomplete optional I/O boards from the PERQ. It turned out I had enough of the hard-to-get chips to make an ethernet_and_canon version, I'd have to add a few TTL parts, etc. So, armed with the PERQ schematics book I set to and did that (well, might as well stick all the options I can in the PERQ, even if I can't get a CX-VDO printer). I even wire-wrapped the QIC-02 tape interface in the corner of that board. I then took the Canon LBP8-A1 apart. Totally apart. I don't just mean into modules, I mean that everything that could come apart came apart. I stripped down the main drive motor. I striped the optical scanner assembly. I traced out schematics. I figured out how the darn thing should work. I then noticed something very interesting. Bob Davis had sent me the wirelist of the PERQ to printer cable. The printer end was a DC37 plug. And if you made a striaght-though cable between a DC37 socket and the 34 pin header on the DC controller in that LBP8A1, the connector that the formatter plugged into (and remember the formatter was the defective part, so getting rid of that would be a Good Thing, then the inputs, outputs, differential signals, etc matched up correctly. It had to be worth a try. I got the printer back together, and got it to print the engine test page. It was remarkably easy to line up the scanner using the IR detector I use for testing rmeote controls. Everything seemed to coue up correctly. So I made up the necessary ribbon cable, made a PERQ printer cable, and put it all togehter. I'd like to say it worked, but that would be a lie. It _almost_ worked. In particular, it did eject a page when I tried to print something from the PERQ. There was even a little column, 16 pixels wide, of printed data. It was my fault. I'd forgotten a kludgewire round the FIFOs on the PERQ interface board. Fitting that, it worked. The only thing missing was the status LED panel. I desoldered bits from the HP control panel (LEDs, switches, 7 segment displayes), leaving 5 LEDs and their series resistors). Soldered a bit of ribbon cable to that, with a socket on the end to fit the right connector on the DC controller. I'd identified the signals with a logic probe beforehand (they're things like 'ready', 'paper out', etc.). Made a new overlay for the panel, put it back in place. It's not original but it works. So I may not be certified, but I think I know a little bit about the insides of these printers. -tony