# File lib/file_systems/AppleCPM.rb, line 172
  def self.delete_file(file_system_image,full_filename)
    catalog=get_block(file_system_image,0)+get_block(file_system_image,1)
    (partial_filename,file_ext)=CPMFile.split_filename(full_filename)
    0.upto(63) do |dir_entry_no|
      dir_entry_start=dir_entry_no*0x20
      dir_entry=catalog[dir_entry_start..dir_entry_start+0x1F]              
      if (partial_filename==dir_entry[0x01..0x08].gsub(' ','')) && (file_ext==dir_entry[0x09..0x0B].gsub(' ',''))      
        #we found a matching filename, so set the 'user number' field to a 'blank' entry
        catalog[dir_entry_start]=0xE5
      end
    end
    
    set_block(file_system_image,0,catalog[0,BLOCK_SIZE])
    set_block(file_system_image,1,catalog[BLOCK_SIZE,BLOCK_SIZE])
  end