PIC16F84_A Interrupt not working
<p>Just started learning PIC microcontrollers. For some reason, <code>PORTB</code> remains <code>0x00</code> and interrupt never occurs. </p>

<pre><code>;*** COUNTER WITH INTERRUPT ***
;***** PIC16FA4_A *************

ORG     0H

STATUS  EQU 03H
PORTA   EQU 05H
PORTB   EQU 06H
TRISA   EQU 85H
TRISB   EQU 86H
INTCON  EQU 0BH
COUNT   EQU 0CH
COUNT1  EQU 08H
COUNT2  EQU 09H

GOTO MAIN

;** INTERRUP ROUTINE **

ORG     04H
INCF    COUNT,1
CLRF    PORTB ; CLEAR RBO
MOVLW   0AH
SUBWF   COUNT
BTFSS   STATUS,0 ;TEST FOR CARRY FLAG
GOTO    GO_ON
GOTO    CLEAR

GO_ON   
BCF     INTCON,1
RETFIE

CLEAR   
CLRF    COUNT
BCF     INTCON,1
RETFIE
;** END OF INERRUPT ROUTINE **

MAIN 
BSF     INTCON,7; GLOBAL INTERRUPT ENABLE
BSF     INTCON,4; RB0 INTERRUPT ENABLE
BCF     INTCON,1; CLEAR INTERRUPT FLAG JUST IN CASE IT IS ON

BSF     STATUS,5
MOVLW   00H     ;ALL RA PINS AS OUTPUT PINS
MOVWF   TRISA
MOVLW   01H     ;RB0 PIN AS INPUT PIN
MOVWF   TRISB 
BCF     STATUS,5

LOOP
MOVFW   COUNT
MOVWF   PORTA   ;PUT COUNT IN PORTA
CALL    DELAY   ;DELAY
MOVLW   01H     
MOVWF   PORTB   ;SET RB0
;EXPECT PROGRAM CONTROL TO GO TO 04H (ORG) BUT IT DOESN'T
;ALSO, USING THE WATCH OPTION IN DEBUGGER, PORTB STAYS 0H
;CAN ANYONE HELP?

GOTO    LOOP

DELAY
LOOP1   
DECFSZ  COUNT1,1
GOTO    LOOP1 
LOOP2
DECFSZ  COUNT2
GOTO    LOOP2
RETURN      

END
</code></pre>

<p>Circuit:<br>
<a href="https://i.stack.imgur.com/J7caf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J7caf.png" alt="enter image description here"></a></p>