PASS -1

begin

 read first input line

 if OPCODE = 'START' then

   begin

    save #[OPERAND] as starting address

    initialized LOCCTR to starting address

    write line to intermediate file

    read next input line

   end {if START}
 else

   initialized LOCCTR to 0
 while OPCODE != 'END' do
  begin
    if this is not a comment line then
      begin
        if there is a symbol in the LABEL field then
          begin
            search SYMTAB for LABEL
            if found then
              set error flag (duplicate symbol)
            else
              insert (LABEL, LOCCTR) into SYMTAB
          end {if symbol}
        search OPTAB for OPCODE
        if found then
          add 3 {instruction lengh} to LOCCTR
        else if OPCODE = 'WORD' then
          add 3 to LOCCTR
        else if OPCODE = 'RESW' then
          add 3 * #[OPERAND] to LOCCTR
        else if OPCODE = 'RESB' then
          add #[OPERAND] to LOCCTR
        else if OPCODE = 'BYTE' then
          begin
            find length of constant in bytes
            add length to LOCCTR
          end {if BYTE}
        else
          set error flag (invalid operation code)
      end {if not a comment}
    write line to intermediate file
    read next input line
  end {while not END}
 write last line to intermediate file
 save (LOCCTR - starting address) as program length
end


PASS 2

begin
 read first input file {from intermediate file}
 if OPCODE = 'START' then
   begin
    write listing line
    read next input line
   end {if START}
 write header record to object program
 initialized first Text record

while OPCODE != 'END' do
 begin
  if this is not a comment line then
    begin
      search OPTAB for OPCODE
      if found then
        begin
         if there is a symbol in OPERAND field then
           begin
             search SYMTAB for OPERAND
             if found then
               store symbol value as operand address
             else
               begin
                store 0 as operand address
                set error flag (undefined symbol)
               end
           end {if symbol}
         else
           store 0 as operand address
         assemble the object code instruction
        end {if opcode found}
      else if OPCODE = 'BYTE' or 'WORD' then
        convert constant to object code
      if object code not fit into the current Text record then
        begin
         write Text record to object program
         initialized new Text record
        end
      add object code to Text record
    end {if not comment}
  write listing line
  read next input line
 end {while not END}
 write last Text record to object program
write END record to object program
write last listing file