hi Thomas,
seem to be you have some errors
this may help you:


start
        bcf     STATUS,RP0   ;change to bank 0
        clrf    PORTB             ;clear portb
        bsf     STATUS,RP0   ;change to bank 1

;Try dont'n use bsf or bcf on ports because first read the
port
;and then write on port, and you just power on the PIC, you
dont'n
;know in what state is the port or do you know ?
 ;       movlw   00H             ;
 ;       movwf   TRISB        ; Set port b as outputs
 ;       bsf     TRISB,7        ; set pin rb7 as input

; this code may help you:

        movlw   b'1000000'    ;
        movwf  TRISB           ; set rb7=input,
rb6~rb0=outputs
        bcf     OPTION_REG,7 ; make internal pull-up on
portb;
        bcf     STATUS,RP0   ; change to bank 0

l001
        call    Delay

;        bsf     PORTB,3 ; set portb pins high
;        bcf     PORTB,2

        movlw  b'xxxxx10x'
        movwf PORTB    ; set rb3 = high, rb2 = low
        call    Delay         ;delay of 18.52 uSec

 ;       bcf     PORTB,3
 ;       bsf     PORTB,2

         movlw  b'xxxxx01x'
         movwf  PORTB   ; set rb3 = low, rb2 = high
          goto    l001        ; the leds change at 1 / ( 2
x delay) = 27 Hz

Delay
         movlw    0x01   ; if you want to see the leds flah
increase the
                                 ; register cou1 to 2
Delay1
         movwf   cou1

Del1

Delay2
            movlw   0xff
            movwf   cou2
Del2

Delay3
            movlw   0xff
            movwf   cou3

Del3
           decfsz  cou3   ; loop3 of 3 x 255 cycles
            goto    Del3    ; loop3 = 71.24 uSec

            decfsz  cou2  ; loop2 = 255 x( loop1 + 5 cycles
)
            goto    Del2    ; loop2 = 13.52 mSec

            decfsz  cou1   ; loop3 = loop2 + 6 cycles
            goto    Del1     ; loop3 = 18.52 mSec

            return
            end


other thing,  you can use the TRIS instruction to avoid the
bank change
but microchip doesnt'n recoment.



Felix Centeno
centella@telcel.net.ve
http://www.geocities.com/CapeCanaveral/Hangar/2372/

----------
> From: Thomas Mxrch <oz2afo@POST8.TELE.DK>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: HELP!!!
> Date: Viernes 14 de Noviembre de 1997 06:43 AM
>
> Hi all
>
>  I'm new at making programs for the PIC* processors. And
now i have some
> trouble, I'm using a 16c84. I have made a very simple
program, that just
> flashes with two led's, sometimes it works (and both
led's flash), but
> mostly it's only one of them flashes, or nothing at all
happens! Is there
> any logical explanation of this behaviour? I'm using a
xtal of 3.579545Mhz,
> 33pf to ground on each side of the xtal, and 100k from
MCLR to VDD. The
> program i'm using is as follows: