Using input from Switch to control a loop

[mister_e]

try this

        SYMBOL PORTB=$06
        symbol TRISB=$86
        POKE TRISB,1 ' PORTB.0 = input, other = output 
        POKE PORTB,0 ' Clear all output
        
main:
        PEEK PORTB,B0
        if BIT0 =1 then goto loop 'enter loop
        'forward
        high 7 'enable pin
        high 6
        low 5
        
        high 4
        low 3
        high 2 'enable pin
        
        goto main
        
loop:
        PEEK PORTB,B0        
        if BIT0=0 then GOTO main 'exit the loop
        'backup
        high 7 'enable pin
        low 6 'stop this side
        low 5
        
        low 4 'reverse this side
        high 3
        high 2 'enable pin
        goto loop

Finger crossed, I don't have PBC