glitch
Veteran Member
I've been using my Morrow SwitchBoard for some simple serial I/O tests lately, since its serial ports are WD 1602 UARTs and require no software initialization. After you set the appropriate switch settings, you can just push bytes into the correct I/O port and the UART will shift them out as serial data. This makes it really nice for debugging, as there isn't an init sequence as there is with the Intel 8251 or Zilog SCC. An added bonus, the SwitchBoard provides both current loop and RS-232 signaling!
I've located a possible source of cheap WD 1602 UARTs and I am considering building a board with a single UART, mainly for debugging purposes. Would anyone else be interested in seeing such a board get turned into a proper PCB layout? I'd probably include 20/60 mA current loop drivers and RS-232 drivers, as well as a FTDI serial-to-USB chip (these work at the TTL level with the UART, and are much more reliable than USB <> Serial converter cables). The board would include an onboard baud rate generator with a dedicated crystal (discrete TTL, no hard-to-find BRG chips) so that it doesn't have to rely on a possibly faulty S-100 bus clock. Looks like interrupt circuitry would be easy to provide, too.
If the UART circuitry turns out to be far too little to fill the board, I could also include simple I/O port driven LEDs/input switches (a la IMSAI front panel) or a DL-2416 ASCII character display. This would recreate a lot of the functionality of my S-100 debug board ( http://www.glitchwrks.com/vintage/s100/debugboard.html ).
Please provide input! Maybe this isn't something anyone else really wants, with the mix of vintage serial boards out there, and the excellent (albeit marginally harder to program) S100Computers/N8VEM Serial IO board.
I've located a possible source of cheap WD 1602 UARTs and I am considering building a board with a single UART, mainly for debugging purposes. Would anyone else be interested in seeing such a board get turned into a proper PCB layout? I'd probably include 20/60 mA current loop drivers and RS-232 drivers, as well as a FTDI serial-to-USB chip (these work at the TTL level with the UART, and are much more reliable than USB <> Serial converter cables). The board would include an onboard baud rate generator with a dedicated crystal (discrete TTL, no hard-to-find BRG chips) so that it doesn't have to rely on a possibly faulty S-100 bus clock. Looks like interrupt circuitry would be easy to provide, too.
If the UART circuitry turns out to be far too little to fill the board, I could also include simple I/O port driven LEDs/input switches (a la IMSAI front panel) or a DL-2416 ASCII character display. This would recreate a lot of the functionality of my S-100 debug board ( http://www.glitchwrks.com/vintage/s100/debugboard.html ).
Please provide input! Maybe this isn't something anyone else really wants, with the mix of vintage serial boards out there, and the excellent (albeit marginally harder to program) S100Computers/N8VEM Serial IO board.