Redesign completed. New board made where all pins are accessible and pads for option of pullups/down resistors.

I have altered the software to use HSERIN and HSEROUT and all is well at the moment. It is working just fine.

Using the code in previous post:

My aim was to display the clock triggered by the gps pps signal. I tried DT_Ints and added the @ INT_RETURN where the original Clock sub had RETURN. This caused the display to only update the very first square with random characters per second with PPS signal.

This is the setup naming Clock. I wasn't sure where to put the INT_Enable . I tried just after this ASM and at beginning of Clock routine with same result.

Code:
;--------------------------------------------------------------------------

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler    INT_INT,        _Clock,      PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM

;--------------------------------------------------------------------------  
@   INT_ENABLE   INT_INT     ; enable external (INT) interrupts