DMP 2120  (260-2811)            Buffer                  Faxback Doc. # 4610

The DMP-2120's ability to temporarily store data is one of its main
advantages over typewriter.  Codes sent to a typewriter (i.e., keys
pressed) 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 call the buffer.  When the buffer
fills, or certain codes are received (i.e., LF or CR), the buffer is
emptied and all data is printed on the paper.  What happens after the
buffer data is printed depends on the circumstances.  In some cases,
printing continues on the same line; in others, the Print Head is moved to
a different position relative to the paper.

In the DP Mode, commands for changing print fonts, Line Feed, etc., can be
stored in the buffer to take affect when the data is dumped to paper.

HINTS AND TIPS ON THE DMP-2120 BUFFER....

* The buffer allocates a fixed number of dots depending on the character
  width selected.  The buffer is emptied when the data stored 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 print line following an automatic Line Feed and Carriage Return.

* The Form Feed code (FF = 12 decimal) automatically activates printing (if
  the code makes it to the Printer).  If LF only has been selected
  (LF-CODE:setting), then the buffer is printed and the print head moves to
  the next Top-of-Form line without a carriage return to the start of the
  line.  Otherwise, the printing position is set at the start of the next
  Top-of-Form line.

* The Carriage Return (CR = 13 decimal) automatically activates printing
  (assuming at least one character code is already in the buffer).  If
  Carriage Return only has been selected (CR-CODE:setting), the printing
  position is moved the start of the current line, but the next buffer full
  will print subsequent characters to the start of the next line regardless
  of the CR-CODE setting.  Otherwise, subsequent characters will be printed
  at the start of the next line.

* The Line Feed (LF = 10) automatically activates printing.  If LF only has
  been selected (LF-CODE:setting), then the buffer is printed and the Print
  Head moves to the next print line without a carriage return to the start
  of the line.  Otherwise, the printing position is set at the start of the
  next print line.

* If the computer delays more than 0.5 second before sending the next print
  code, the buffer is printed.  Printing continues from the current
  position.

* The Dot Positioning sequence (27 16 n1 n2) prints the buffer, if the
  designated position is at the left from 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 in the
  current line at the dot address specified by the command.

* If a character set of different dot density is selected, the data in the
  buffer is printed.  Codes for changing character sets are: 27 17, 27 18,
  27 19, 27 20, 27 23, 27 29.  Printing continues in the current line with
  the new character style.

* When the start Graphics Mode (18) is received followed by the Standard
  or Condensed characters, the buffer is printed.

GRAPHICS MODE ONLY:

* When the end Graphics is received and returns to a Standard of Condensed
  character printing condition, the buffer is printed.

The Printer returns to the previous print mode and printing continues in
the same line from the current print position.

NOTE #1: In the description, "next line" means the new line performed by
Line Feed operation.  In Data Processing Mode, if a Reverse Line Feed has
been set in the memory, the line feed operation will cause paper to move in
the reverse direction.

NOTE #2: Repeat data can cause a buffer full or overflow condition, but the
overflow characters are ignored and not printed at the start of the next
line.

The optimizer function allows the following: If the printer receives a
spacing code (fixed space and/or proportional space), the carriage moves
only the shortest distance, and the action takes place without unnecessary
movement.  This saves printing time.

This function is canceled, and uni-directional printing is performed if the
PRT DIR setting is set to UNI DIR on the control panel.  This increases
printing time but offers better fine vertical alignment.  When the
character data (SP, proportional space, or printable code) is sent to the
printer within a 0.5 second interval, the printer automatically stores it
until (1) function codes are sent, or (2) the interval is more than 0.5
second.  Printing is then executed.

(smm 07/26/93)

Privacy Policy