baud modifier

Doesn't much matter - the task is simple enough that pretty much any architecture will work. Heres some things to consider when selecting one: - Two UARTS - as noted previously this is not a show-stopper requirement, however it will make your life a lot easier. The alternatives are to bit-bash the slower port which requires careful timing and/or interrupts and is probably not a good starter project, or to add an external UART - which means you will have to wire an external bus. - Internal RAM. The more the better, because the larger you can make your buffers, the more efficient your flow control will be (there's always some small delay with starting/stopping ... especially of you need to use XON/XOFF type control). Assuming you have flow control available, then 128-256 bytes in each direction should be fine (if the fast computer never asserts flow control on receive data then you could get away with less (none) on the slow->fast direction. If the fast side does not accept fow control, then you are going to need a LOT of buffer in the fast->slow direction and you will most likly have to wire an external bus with external memory. With hardware flow control you can probably get away with less, XON/XOFF you might get away with 64 - I've seen 30-40+ characters come out of some devices AFTER the XOFF character was received, so plan your code accordingly. - Flash based - if don't have programming tools, embedded debuggers etc. a flash based MCU will be much easier to work with - normally you just need a cable to your PC and you simply reload code directly into the microcontroller flash. - Any of the 8-bit Motorola, Intel, Atmel or many others should do fine, use the above criteria to pick a really suitable one. 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