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

The DMP-2110's ability to temporarily store data is one of its main advant-
ages 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 con-
tinues 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 cur-
rent 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)