RC-reset circuits are highly problematic, because of several points:

1. If rise time of Vcc on power-on is much bigger than time constant of RC-reset circuit, then no high pulse will ever be seen at the reset input pin! Assume you power the micro by a tiny and weak mains transformer, then several mains half periods might be needed to swing to nominal Vcc level. So, rise time of Vcc on power-on can last up to 10...20msec. With the time constant of your example, namley 100nF x 1k = 0.1msec, proper generation of reset pulse cannot be guaranteed.

2. Even if the time constant of RC-reset circuit is properly chosen, it's still needed that mains voltage is nominal during the power-on. But if a short dip occurs, proper generation of reset pulse cannot be guaranteed.

3. RC-reset circuits cannot produce any reset signal when Vcc falls! So, small Vcc dips can make the micro to run ill.

Micros containing a flash code memory don't like very much power-ons and power-downs without reliably activated reset line. It's reported many times, that corruptions of code memory has been observed. So, it's always highly recommended to use a proper reset chip, when a flash micro is used, even if this chip might be more expensive than the whole micro. The reset chip must guarantee a proper reset pulse on power-on AND power-down (and during dips, of course), and this equally how long the rise and fall times are.

James, take note, that the MAX1232 contains a watchdog, which cannot be switched-off, but must periodically be "fed".

Kai