Laser 128 - Before Using Draw

3.11.4
BASIC COMMANDS AND STATEMENTS
Before using DRAW, XDRA W, ROT and
SCALE
Before you can us e any one of the following
commands: DRAW, XDRA W, ROT and
SCALE, make sure you h ave done the
followings:
1 Entered the s hape tabl e
2 Told the computer where the shape t ab le
is
Item I has been discu ssed in the previous
pages. Item 2 is a very simp le task; ju st enter
the starting address of the shape taMe into
hex locati on $E8 (lower two digits) and $E9
(upper two digits).
For example, if your s hape table resides
from address $1000 on, you can enter the
computer's monitor (CALL-151) and type the
following:
*E8:00 10 <RETURN>
T ype CTRL-C and RETURN to go back to
BASIC. Computer is now ready to interpret
your s hap e command.
As the vectors can only point to either the
left or right or up or down, diagonal lines
must be approximated by a number of them
which, taken together, give the impre ss ion of
a dia gona l line. This is shown below:
.-i .
·-·-1
i
Figure 4. Vectors for a diagonal line
II-34