like this maybe


Code:
myarray var byte[4]  ; a 32 bit array
  nbyte  var byte                     ;result
 
 inx    var byte                         ;start index in array
  x    var byte

arraywrite myarray,[105,100,10,116] ; fill array


 inx=3                                        ;  start a bit 3
 nbyte=0                                   ;clr result

 for x= 0 to 3                               ;get the 4 bits             
 nbyte.0[x] = myarray.0[x+inx]
 next

 serout2 PORTa.0,84, [13,10,"nb ",bin4 nbyte ]