> My key need is the ability to directly manipulate the device-side
> lines (gpio, dtr, etc) from a Linux program. I know FTDI can do that,
> I don't know if SI can.
From the quick read I've done of both data sheets, it appears that the CP2103 only has Windows drivers for the direct control. I am running mostly under Linux, so that gives another plus for the FT232R.
With direct control of the GPIO outputs on either chip, it seems you could set it up to control the reset and mode pins on the R8C/etc. for programming without using jumpers. I suppose you could also use these pins to make a programmer for a PIC, without having to go through the gymnastics that the typical PIC serial programmer has to do, except for needing +12v or so depending on the version of the PIC. Of course, you'd still have a serial output available to act as a terminal, or whatever ...
DJ, I've done a little looking at your website. Do I understand that you have done a port of gcc to output code for the R8C/M16/M32 processors? Is there a minimum program memory size needed to use this rather than assembler?
Thanks so much to all for furthering my education ... now I've just got to find the time to try some of this out!