Using Delay Loops to blink LEDs

This simple bit of code will cause the LED on the LAB-X3 to blink on and off.

     
  
;
; BLINKY.ASM
;
; This simple bit of code should allow us to blink two LEDs
; attached to
; The LAB-X3 board.
;
    TITLE "Blink the LEDs on LAB-X3"
    LIST   P=PIC16F628, R=HEX, C=120, N=50
    include "P16f628.inc"
    ;
    ; Very important! If you're using the LAB_X3 these fuses
    ;        _LVP_OFF - Low Voltage Programming (Disabled)
    ;        _MCLRE_OFF - MCLR/Reset (Disable)
    ;       _LP_OSC - Low Power Crystal Oscillator (Enable)
    ; Must be set. Otherwise the board just doesn't run.
    ;
    __FUSES _CP_OFF&_LP_OSC&_WDT_OFF&_LVP_OFF&_MCLRE_OFF
        
;
; Data bits 
;
    CBLOCK  H'20'
            COUNT
    ENDC
        
I_CNT   EQU     H'1'             ; Initial Count
LED1    EQU     4
LED2    EQU     5
                                              
;
; Initialization
;
    ORG     H'0000'         ; Start VECTOR
    NOP                     ; Space                
    GOTO    MAIN            ; Go to MAIN 
    
;
; * * * * * * * * * * * * 
; *       M A I N       *
; * * * * * * * * * * * * 
;
; Main Body with initialization Etc.
;
MAIN:
    BSF     STATUS, RP0     ; Select Bank 1
    MOVLW   B'0000111'      ; Set TMR0 prescaler to 256
    MOVWF   OPTION_REG      ; Store in the OPTION register
    BCF     PORTB, LED1     ; Enable LED 1 and 2 as outputs
    BCF     PORTB, LED2     ; 
    BCF     STATUS, RP0     ; Back to page 0
    MOVLW   I_CNT           ; Initial Count load
    MOVWF   COUNT           ; For the first loop
LOOPER:
    BTFSS   INTCON, T0IF    ; Did TMR0 overflow?
    GOTO    LOOPER          ;     Nope so keep waiting        
    BCF     INTCON, T0IF    ; Reset the TMR0 flag.
    DECF    COUNT,F         ; Decrement Counter
    INCFSZ  COUNT,W         ; check for underflow
    GOTO    LOOPER          ; Nope, keep counting
    ;
    ; Timer overflowed Count times so we toggle the LED
    ;
    MOVLW   I_CNT           ; Restore counter value
    MOVWF   COUNT           ; With default value
    BTFSS   PORTB, LED1     ; If LED1 is on, turn it off
    GOTO    $+4             ; If its off jump to turn it on
    BCF     PORTB, LED1     ; Turn LED1 off and
    BSF	PORTB, LED2     ;         ... LED2 on
    GOTO    LOOPER
    BSF     PORTB, LED1     ; Turn LED1 on and
    BCF     PORTB, LED2     ;         ... LED1 off
    GOTO    LOOPER
    END

 
  Listing 1: LED Blinking Program