OPTION_REG = OPTION_REG & $80 | 1 ; Set TMR0 Prescaler to 256, leave RBPU alone
por value for OPTION_REG is 255 (0b11111111)

OPTION_REG & $80 | 1 results in OPTION_REG =129 (0b10000001)
that is not the result you are describing in your comment ; Set TMR0 Prescaler to 256, leave RBPU alone
it also sets the int Interrupt to falling edge of INT pin
for 256 prescaler OPTION_REG bits 0:2 = 0b111

next issue your code is not posted in code tags which makes life difficult .

what do you think will happen to the bit timing accuracy of a software timed serial output routine like debug when you interrupt it 100's of times per second