DMP 107 (260-2821)                Buffer               Faxback Doc. # 4502

Size: 1 Line

PRINTER BUFFER OPERATION

The printer's ability to temporarily store data is one of its main advantages 
over a typewriter. Codes sent to a typewriter (that is, keys you press) are 
transferred immediately to the paper.

Codes sent to a printer are not printed immediately; they are stored in a 
separate section of memory in the printer called the buffer. When the buffer 
fills, or certain codes are received (that is, LF or CR), the buffer is 
emptied and all data is printed on the paper. What happens after the buffer 
data prints depends on the circumstances. In some cases, printing continues on 
the same line; in others, the print head moves to a different position 
relative to the paper.

In the DP mode, commands for changing fonts, line feed, and so on, can be 
stored in the print bufferN THE PRINTER BUFFER

FOR DP, WP, AND GRAPHICS MODES:

* The buffer allocates a fixed number of dots, depending on the character
  width selected. The buffer empties when the stored data equals that number.  
  Printing resumes at the start of the next line.

* The last character received by the buffer is printed at the start of the
  next line following an automatic line feed and carriage return.

* The form-feed code (FF=12 decimal) automatically activates printing (if 
  the code is received bing (if the code is received by the printer). The
  buffer prints and the print head moves to the next top-of-form line 
  without a carriage return.

* The carriage-return code (CR=13 decimal) automatically activates printing
  (assuming that at least one character code is already in the buffer). If 
  you select carriage return only (DIP Switch 4), the printing position 
  moves to the start of the current line, and the next buffer full prints 
  subsequent characters over the current line. Otherwise, subsequent 
  characters print at the start of the next line.

* The line-feed code (LF=10) automatically activates printing. The buffer
  prints and the print head moves to the next print line without a carriage
  return.

* If the computer delays more than a second before sending the next print
  code, the buffer prints. Printing continues from the current position.

* The dot positioning sequence 27 16 n1 n2 prints the buffer if the desig-
  nated position is to the left of the current position. Printing continues
  in the current line at the dot address specified by the 27 16 command.

DATA AND WORD PROCESSING MODES ONLY:

* The backspace command activates printing. Printing continues on the cur-
  rent line at the dot address specified by the command.

* If you select a character set of different dot density, the data in the
  buffer prints. Codes for changing character sets are: 27 17, 27 18, 27 19,
  27 20, 27 23, 27 29, 27 31, and 27 32. Printing continues in the current
  line with the new character style.

* When the printer receives the start graphics mode code 18 followed by
  standard characters, the buffer prints. Dot graphics printing continues 
  from the current character position.

GRAPHICS MODE ONLY:

* In the description, "next line" means the new line reached by performing 
  a line feed operation.

* Repeat data can cause a buffer full or overflow condition. The overflow
  characters are wrapped around and printed at the beginning of the next 
  line.

(dtc-07/26/93)