DMP 2110  (260-2110)            Buffer                 Faxback Doc. # 4335

The DMP-2110's ability to temporarily store data is one of its main
advantages over a 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 called 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 print buffer until data is printed.

Understanding how the buffer works is important for those who wish to gain
full control of the DMP-2110.

HINTS AND TIPS ON THE DMP-2110 BUFFER

For DP, WP, and graphics modes

* 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 (with #3-8), then the buffer is printed and
the print head moves to the next top-of-form line, without a carriage
return to move the print head to the beginning off that line.  Otherwise,
the printing position is set at the start of the next top-of-form line.

* The carriage return code (CR=13 decimal) automatically activates printing
  (assuming at least one character code is already in the buffer).  If
  carriage return only has been selected (switch #3-7), the printing
  position is moved to the start of the current line, but the next buffer
  full will print subsequent characters at the beginning of the next line,
  regardless of switch 33-7.  Otherwise, subsequent characters will be
  printed at the start of the next line.

* The line feed code (LF=10) automatically activates the printing.  If LF
  only has been selected (switch #3-8), then the buffer is printed and the
  print head moves to the next print line, without a carriage return to
  move the print head to the beginning of that line.  Otherwise, the
  printing position is set at the start of the next print line.

* If the computer delays more than 0.5 seconds 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 to the left of the current position.  Printing
  continues in the current line at the dot address specified by the
  (27, 17) 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 the character sets are: (27,17),
  (27,18), (27,19), (27,20), (27,23), and (27,29).  Printing continues in
  the current line with the new character style.

* When the start graphics mode (18) is received followed by standard or
  condensed character, the buffer is printed.  Dot graphics printing
  continues from the current character position.

GRAPHICS MODE ONLY:

* When the end graphics is received and returns to a standard or 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.

NOTES:

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

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.

(css 07/26/93)

Privacy Policy