I know how frustrating it can be to get this problem. It cost me several hours (and a dead USB to RS232 dongle) to isolate my problem. It turns out the internal oscillator (4Mhz) on my 12F629 was too far off. I probably killed the internal calibration value by mistake at some other time.


"for a= 0 to 255"

You are getting some data in acceding order. Using printable characters can help by counting the number of correct ascending order before it breaks consistent order. The control characters can be muddying up things. Maybe:

for a=32 to 126 'send only printable characters

Also, characters pacing might help

DEFINE CHAR_PACING 1000 'character pacing of 1ms

My Hyper Terminal setting is on ASCII (chosen from a list in the setup)