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Vector Graphic MP Dot Matrix Printer
NOI'E:
It is strongly suggested that in order to maximize printer life only
lubricants purchased from Vector Graphic be used.
Any substitution will
result in shortened printer life.
First interval lubrication
The points illustrated in the appendix under "Lubrication Points-Printer"
must
be
lubricated using t...lJ.e lubricants specified on the diagram at least
once every
6
rronths or
1
million lines of use, whichever comes first.
Second interval lubrication
The points illustrated in the appendix under "Lubrication mints-Ribbon
Mechanism" MP ribbon mechanism must
be
lubricated with
G2
lubricant every
2-1/2
million lines or every six months, whichever comes first.
Third interval lubrication
It is suggested that your MP dot matrix printer
be
overhauled by your
Vector Graphic Dealer every
5
million lines of use to assure dependable long
life.
2.7 Special Graphics Characters
The MP Graphics Dt"iver Fran is available as standard equipment.
In order
to understand how to create special graphics characters, it is necessary to
know how "normal" characters are generated and printed.
The same principle
is used whether the output is a printed letter on a page or a number on a
video display.
What happens is
t..~is:
in response to a ccmmand to print an
ASCII character, the operating system or high level language consults a look
up table already in canputer merrory.
It obtains from this table the column
codes of
~~e
letter it is going to print.
TIlere are as many column codes as
the character matrix is wide.
For example, for the MP the number of column
codes required for each character is 5.
The column codes are eight bit
binary numbers, generally expressed as two hexadecimal digits.
For example,
in response to a cOfmI'and to print the ASCII letter "R", the system would
find in the look up table the following five column codes:
11111110,
00010010, 00110010, 01010010, 10001100.
(In hex, FE,
12,
32, 52 and 8C.)
You will notice that since the matrix is 5X7, the least significant bit is
not used and is always
O.
Thus,
t.t~e
numbers are always even.
These binary
numbers are plotted on a 5X7 grid, starting with the first (most
significant) bit of the first number which is plotted as the first dot or
non-dot at the bottom-most point of the first colwm.
You then plot up L'1e
column, converting each one to a dot and each 0 to a space (non-dot).
\IIIhen
you reach the eighth (least significant) bit, you ignore it and start on the
leftmost bit of the next column code continuing in this manner until the
fifth column code is completed.
2-12
Rev. I-B 6/7/80
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