Electronics Master wrote:

> WHAT IS WRONG ?????????

  Caps for code please, not conversation.

> PIC 16F84 TO CHECK (OPEN-CLOSE) PORT B,1
> AND IF PORT B,1 IS SET = 1
> THEN MAKE PORT B,4 SET = 1

>  LIST P=16F84
>  PORTB EQU 06H

;  You should be using something like:
;----------------------------------
  LIST P=16F84

;  suppress nuisance warnings:
  errorlevel -224
  errorlevel -305

;  Include standard defines
  INCLUDE "\pic\mpasm\p16F84.inc"


>  START
; This is a *label*.  Must be in first column.

>  TRIS PORTB
; You haven't given it a value in W to use to set the TRIS register.
; I think you want to MOVLW 0x02 just before this to set PORTB,1 as the
; only input.  Do *not* connect unused pins to a supply rail.
; You only need to set the TRIS register once anyway, so the loop point
; can occur after this.  With due respect to Andre, forget bank
; switching!

>  BTFSS PORTB,1
>  GOTO START

; So, if PORTB,1 is zero, there is no way to zero PORTB,4?

>  BSF PORTB,4
>  GOTO START

>  ORG 3FFF
> END
; You don't need to ORG an END statement.

> WHAT IS WRONG ?????????

  Everything!

  Try:
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  LIST P=16F84
;  suppress nuisance warnings (should be in include file actually):
  errorlevel -224
  errorlevel -305

;  Include standard defines - actual path depends on your installation:
  INCLUDE "\pic\mpasm\p16F84.inc"

        ORG     0
        GOTO    START

; Jump over interrupt vector.
        ORG     0x10
START   MOVLW   0       ; All outputs in
        TRIS    PORTA   ;  port A unless otherwise used.
        MOVLW   0x02    ; Bit 1 is input, all others outputs
        TRIS    PORTB   ;  in port B
        CLR     PORTA   ; Start with
        CLR     PORTB   ;  a clean slate

LOOP1   BTFSC   PORTB,1 ; If input set,
         BSF    PORTB,4 ;  set output
        BTFSS   PORTB,1 ; If input clear,
         BCF    PORTB,4 ;  clear output
        CLRWDT          ; Just in case you had it enabled
        GOTO    LOOP1   ; loop forever ....

        END
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  No warranty applies to this code.
--
  Cheers,
        Paul B.