Commodore CBM - Screen Display; The PET Video Screen

SCREEN DISPLAy
The PET screen is a high-resolution video display; it is similar to a black-and-
white television set. The display has 1000 character positions, arranged as 25
rows, with 40 characters per row. The PET screen is illustrated in Figure 2-5.
r-o! .----40 columns----.~
l
~
0: 25 x 40 = 1000 Characters
Ln
N
J
Figure 2-5. The PET Video Screen
One-fortieth of each display line, therefore. becomes one character position. The
PET can display 64 dots in a single character position, organized as a block that is
8 dots high and 8 dots wide. Characters are generated in any character posi-
tion by displaying
appropria te dots within the axa dot block, or matrix. This
is illustrated in Figure 2-6.
Although lines on the PET display screen are only 40 characters wide,
logically lines may be up to ao characters wide. This is another example of
what vou see differing from what the PET records. To the PET. lines can be up ta
80 characters long. The end of a line is recorded by the PET when vou press the
RETURN key. But the PET will insert its own RETURN after the 80th character.
ending the line, if vou attempt to type an 81st character as part of a single line.
The
PET will display a line of more than 40 characters using two screen dis-
play rows.
When vou type a 41 st character. the cursor automatically moves to the
first character position of the next row. and displays the character vou type; the
display looks
as though vou had typed a RETURN after the 40th character. even
though Vou have not.
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