Apple IIe - Page 232

232 Apple lie Users Handbook
vi de random values for the variables Land M , which have a range
from 0 to 34 inclusive.
310 L = 34*RND(1)
320 M = 34*RND(1)
330 RETURN
The ideas
in this section by no means exhaust the possibilities
that could be added to "BARACADE." Other upgrades might
include : keeping track of the high score, or adding another
player. The only two limiting factors are execution speed and
one 's imagination.
HIGH RESOLUTION GRAPHICS
The
Apple can also be configured to display one of two high
resolution graphics formats. A graphics-only display is available
that has a resolution of 280x192 pixels. Also, a graphics plus text
display is available that has a resolution of 280x160 pixels. In this
mode, four lines of text are located beneath the graphics display.
Commands
All high resolution graphics commands directly parallel their low
resolution counterparts . Therefore , familiarity with the low
resolution commands will be assumed throughout the remainder
of this chapter.
The HGR
command can be used to configure the computer to
display the graphics plus text format . The command clears the
display memory (2000-4000 Hex) , so that the screen will initially
be black.
HGR set
high-resolution
graphics+ text
The HGR command does not clear the high resolution " next
color " register.
The
four lines of text that appear beneath the graphics mode can