vincelee@tornado.Berkeley.EDU (Vincent H. Lee) (03/06/91)
Well, I've just built Jeff Lavin's PD I/O board, and am, for now disappointed. The board is well made and the instructions pretty thorough, except when it comes to the parallel port. It seems that the serial interface was the main point to the board, and the parallel interface purely secondary. PROBLEMS: 1) The parallel port software configures incomplete parallel ports. Let me explain... Each 85C22 (btw, I think the Motorola 6821 may be equivalent, and readily available for about $3) provides 20 i/o pins. Rather than configure a complete parallel port for each chip, the provided eightbit.device configures two 10-pin (no busy, pout, or sel) parallel ports per chip. 2) The test software and eightbit.device fail on my machine in 020 mode. They simply hang. Apparently, either the select is too short for my printer to recognize it, or it doesn't recognize the acknowlege, as I can trick the computer to continue by feeding signals into ACK when the software locks up. 3) Bugs. This one really confuses me. In 68000 mode, the port seems to work fine. However, when I try dumping a bitmap to my HP Paintjet, the paintjet prints the image, but does so one row of pixels at a time and feeding one pixel row after each pass. I don't know what could cause this, and wouldn't believe it was even possible it I hadn't seen it myself. Any ideas? 4) Source. The source code is in Macro68 assembly. I've had a hell of a time converting this code to plain vanilla assembly. Anyway, if anyone could help me, I'd appreciate it greatly. I hope you can understand me, as it's 3:30am and I'm only half awake. Thanks. PS: Also, I've been trying to convert ParNet to work with the board. Is the source to it available? I've been working with a disassembled version. I think I can do it, but a legit source would make it much easier. -Vince