subroutine apset(icx)
c this subroutine allows the user to request a
c certain aperture bias voltage data to be processed.
c
c jhwjr 27 oct.,82 subroutine written

      byte icx
      common /deluns/jlun,junin,junout

      write(*,10)
  10  format(' enter desired aperture bias voltage',/,
     1  ' 0,2,4,8, or a for all: ', $)
      read(*,20) icx
   20 format(a1)
      return
      end