While Loops Slow??

[skimask]

The pic is running at 20MHz.

PortA is connected to the old piece of equipment circa early 80's running 6800 microprocessor to drive an 18-segment display. I am working to replace the display with a newer dot matrix display. I pelieve the 6800 clock is 500KHZ, but could be wrong.

The signals on PortA are TTL level, and change with every clock cycle on the 6800.

The code shown was just test code to see if I can consistantly read the data, which it turns out I cannot.

Are you sure the PIC is running 20Mhz? Could be running on the internal 'failure' clock.
Does a one-second blinky LED actually blink at one second intervals?

Also, check up on using the LAT register vs. the PORTx register...

How fast is it actually running thru the loop? 1x per second? 100x per second? 10000000000000000000000x per second?
Can you measure it?