dplatt@coherent.com (Dave Platt) (09/20/90)
I'd like to homebrew a protocol converter, to connect between a Macintosh II and a printer with a standard Centronics parallel interface (an HP DeskJet 500). I believe that I can do this with an off-the-shelf UART, a clock circuit, and a handful of glue chips; I'm looking for advice as to which UARTs would be well-suited to the application. What I'd like: - Capable of high speed operation (57.6 kbits/second if at all possible; 38.4 would be acceptable. A UART limited to 19.2 kbits/sec won't cut it). - All options jumper-selectable... I don't want to have to put a microprocessor in the converter to drive the UART via a bus. - At least a few bytes of on-chip buffer memory... the more the merrier. - Support for hardware flow control when the buffer starts to get full. - A simple data-ready/strobe interface on the parallel side. - Capable of working with one of those nice Maxim (?) TTL-to-RS232 interface chips. - Reasonably low power, +5 supply only, capable of driving standard TTL loads. - Available off-the-shelf. Is there such a beast on the market today? Yeah, I know I could buy a serial-to-Centronics converter box... but most of them don't seem to run at above 19200 bits/second, and the cheapest I've seen costs in the neighborhood of $100. I'd like something cheaper and faster, if possible.