PortD mistery

Hi, I'm just going mad. Wish somebody could help.
I'm making a tracked rover using a PIC16F877/20 and the classical SN754410.
I've got the H-Bridge connected to portd 0-6, separate 12 volts power for the motors, capacitors and so on.
I double checked everything about 30 times but only one of the two motors runs in both directions, (pin 2-3), the one connected to pin 0-1 only goes one way.
After all day measuring, checking, using multimeter etc, I just moved the control on portc and everything works smoothly.
I can't really understand why.
By the way, I tried with another SN754410 (just in case...), another 877 (just in case), I swapped motors.
I mean, everything was OK.
Any idea of where is my mistake? (I'd like to sleep tonight)
Tx.

About the only thing that can interfere with PORTD on an 877, is the Parallel Slave Port (PSP).

Occasionaly people will set TRISE = %11111111 thinking it sets PORTE to all INPUT. But it actually turns on PSP mode on PORTD, because Microchip used the extra bits in TRISE for something other than TRIS.
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I actually set TRISE=00000000
It shouldn't be that.
Any other idea?

Quote:

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I actually set TRISE=00000000

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Surely you meant TRISE=%00000000

Al.