baud modifier

I've see a number - for various reasons. - Some use DIP switches to set the rate, so the limit it to "common" settings, and in post-TTY days, "nobody uses 110". - Some use an off-the shelf baud rate generator (often tied into a UART like the 6552), and for whatever reasons, provided it with 1/2 the rate clock - this 300 becomes 150, 600 becomes 300, 1200 becomes 600 etc.... since the off-the-shelf parts don't do 220, 110 gets lost. - Some just don't "feel" like offering all the available options provided by the hardware. If the device is dedicated to <high-speed> to 110 bps conversion, bit-bang might make sense - At 110, bit-bang is pretty easy, and can be accomplished with a simple interrupt without too much overhead (and what overhead it does cause isn't enough to swamp the box which is doing a very simple function otherwise). I'd go bit-bang for the 110bps port on a single-chip micro before I'd go to the hassle of wiring up an external bus, no matter it it's to an ISA card or another dedicated UART. As someone else pointed out, if size & power requirements are not a concern, this would be very easily done with an old PC - even an XT would have plenty of go for this job. Dave -- dave06a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.classiccmp.org/dunfield/index.html