This is a 3 byte execute in the same quad-a bug in the listing reported at reference B. Locate buffer. If found return else prepare to display an error message-see ref C. Check whether flag 25 is set if yes return else continue with this routine. Call the routine to enable and clear the display. Call the routine to display the following characters. 200 Hex has to be added to this character to end msg. Call routine to enable chip 0, set the message flag and print the message if the printer is in trace mode. Call a smart routine to handle back step after an error and to compute a valid line number then return. This part of the code determines how much space there is in the file. A contains address of datafile buffer Select this register Read it Store in M for later use Select chip 0 Recall M and store in Q. We will need the data file pointer later-see ref A for details of this bufffer. Set A[X] to pointer value. Move data file size to C[X]. Exchange C and A[X] Differnce gives number of registers for storage Hold in C Recall M. Place number of reg in C[X] Store in M Return Code to locate and calculate number of buffer register. See reference A. Code is from F236 to F24D leaving N containing the buffer header with N[X] containing the address of the header.