Considering the amount of replies which I received to my previous
questions, it would be unfair to not share what I have been working on.
It is, in fact, just a simple robotics experiment.  A robot which finds
its way out of a maze.  The switching question I asked was to switch a
digital voice recording module @ approx. 6V.  The 4066 worked great,
thanx for the advice.

        Now for the bad news.  I must once again enlist the services of you all
in order to get this off my desk (and my mind!).  Here are the
questions...

1.  The sensors which I have are modulated light sensors, ripped old
video game guns, but have analog outputs.  Is there any way to change
this without implementing an A/D converter?  If not, where can I get a
digital version.

2.  I'm assuming that servos would be easier to implement in this type
of project than geared down motors, but this is only an assumption...

3.  My code should be much shorter and neater than what it is.  (Then
again, I may have a future with Microsoft ;-)  In fact, I'm not even
sure if it will work.  There must be a better way to do 'If..then' on a
PIC.  Actually, is there any way to use a look-up table on a PIC?  Which
would be better?  The code follows.

Any posted responses or web resource pointing would be greatly
appreciated.

                                Synergetix


**WARNING: the following code is plain UGLY.  Reader discretion is
advised***

Here's the partial code with explanation
; robot program v1.1
; robot navigates through maze

; PORTB:
; 0= Right motor -
; 1= Right motor +
; 2= Left motor -
; 3= Left motor +
; 4= Right sensor
; 5= Left sensor
; 6= Front sensor
; 7= Switch

; what 'main' should accomplish:

; if fsensor on, lsensor off, turn left
; if fsensor on, lsensor on, rsensor off, turn right
; if fsensor on, lsensor on, rsensor on, turn around

; if fsensor off, rsensor off, turn right
; if fsensor off, rsensor on, lsensor off, turn left
; if fsensor off, rsensor on, lsensor on, go forward

; in other words:
;                       F       L       R            x
;                       0       x       0       right
;                       0       0       1       left
;                       0       1       1       forward
;                       1       0       x       left
;                       1       1       0       right
;                       1       1       1       turn around


; INCLUDES AND JUNK

        processor 16f84
        include   <p16f84.inc>
        __config  _RC_OSC & _WDT_OFF & _PWRTE_ON

; VARIABLES

J       equ     H'10'           ; J = hex 10
K       equ     H'11'           ; K = hex 11
SENSOR  equ     H'12'           ; SENSOR = hex 12

; MAIN

        org     0               ; start at beginning
        movlw   B'01110000'     ; set input (1) and output (0)
        tris    PORTB           ; set I/O

ploop:  nop                     ; program loop

; move forward

        movlw   b'00001010'     ; move to acc. (forward)
        movwf   PORTB           ; output
        call    motdel          ; motor delay time

; check sensors

        movf    PORTB           ; move port B to accumulator
        movwf   SENSOR          ; then move to memory

        btfsc   SENSOR, 6       ; check for wall at front
        goto    fwall           ; if yes, go to fwall

        btfss   SENSOR, 4       ; check for wall at right
        goto    rgt             ; if no, go right

        btfss   SENSOR, 5       ; check for wall at left
        goto    lft             ; if no, go left

        goto    ploop           ; else go forward


fwall:  btfss   SENSOR, 5       ; check for wall at left
        goto    lft             ; if no, go left

        btfss   SENSOR, 4       ; check for wall at right
        goto    rgt             ; if no, go right

        goto    rev             ; else reverse


; turn motors left

lft:    movlw   b'00000110'     ; move to acc.
        movwf   PORTB           ; output
        call    motdel          ; motor delay time
        goto    ploop

; turn motors right

rgt:    movlw   b'00001001'     ; move to acc.
        movwf   PORTB           ; output
        call    motdel          ; motor delay time
        goto    ploop

; turn around

rev:    call    lft             ; turn 90 degrees
        call    lft             ; turn 90 degrees again
        goto    ploop


; SUBPROCEDURES

motdel  movlw   D'80'   ; w := 80 decimal
        movwf   J       ; J := w
jloop:  movwf   K       ; K := w
kloop:  decfsz  K,f     ; K = K-1, skip next if zero
        goto    kloop
        decfsz  J,f     ; J = J-1, skip next if zero
        goto    jloop
        retlw   0

        end