1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
'PLOT x,y' sets the specified point to the current color. Coordinates
start with 0,0 in the top-left corner of the screen, and increase
towards the bottom and right. While there is no arbitrary lores line
function, there is functionality to draw horizontal or vertical lines.
They have the following form: 'HLIN x1,x2 AT y' and 'VLIN y1,y2 AT x'
'SCRN(x,y)' will return the color (0-15) of the pixel at coordinated
x,y.
'TEXT' will get you out of Lores or hires graphics mode (with a lot of
ugly garbage where your lores screen was; you may want to do a 'HOME'
to clear the screen after switching out.
3.5 High Resolution (Hires) graphics:
Apple IIs with at least 16K of memory (24-32K if you want to use an OS
as well) have the ability to draw on a 280x192 hires graphics screen;
24K (36-48K if an OS is desired) for the second independent screen.
All Apple IIs capable of drawing that can draw in 4 fixed colors; past
the first few revisions of the Apple ][ motherboard, there are 6 fixed
colors. [Technically 8 colors, but since there are two slightly
different whites and two blacks, that's 6 real colors]
Hires is also a root beer, but that's outside the scope of this FAQ.
[And no, I don't have that picture online.]
The 'HGR' command will turn on the first hires screen to a mixed
280x160 mode with 4 lines of text at the bottom, and clears the
graphical section to all black. [It may not move the current prompt
down there, so hit return if you seem to have lost the cursor.]
'HCOLOR=n' sets the color for drawing. Valid color numbers are 0
(Black 1), 1 (Green), 2 (Violet), 3 (White 1), 4 (Black 2), 5
(Orange), 6 (Blue), 7 (White 2).
The graphics drawing commands are much more intelligent than in
lores-- you can draw lines of any angle, as well as points. 'HPLOT
x,y' turns on that pixel. 'HPLOT x1,y1 TO x2,y2 [TO x3, y3 [TO
x4,y4]]' draws a line or series of lines in a row; you can also do
'HPLOT x1,y1: HPLOT TO x2,y2' and the like. Coordinates start with 0,0
in the top-left corner of the screen, and increase towards the bottom
and right.
Colors have some strange properties-- colors 1 and 5 can only appear
in even numbered columns, 2 and 6 only in odd-numbered columns. Any
two adjacent "on" pixels will appear white. [This is all due to the
hardware display methods]
'HGR2' turns on the second hires screen, and clears it to black. It
also displays all of it (280x192) with no text visible at the bottom.
[There's no easy way to get both the second hires screen and 4 lines
of text onscreen in a "mixed" mode as with lores and the first hires
screen without relocating the BASIC program in memory, some loops to
do memory copying and the like.] You can draw to the second hires
screen the same way as with the first-- the commands are identical. By
tweaking softswitches and other locations, you can draw on one page
while displaying the other, and other fun tricks.
For the technically inclined, some more info about the single
(regular) hires screen. It's 280x192 pixels in size, taking a $2000
byte chunk of memory starting at either $2000 ("page 1") or $4000
("page 2"). It's not linearized either, and has some 'holes' in the
display to make it fill up to $2000 bytes in size. [Each row takes 40
bytes, so after 3 rows, there's 8 unused bytes to make it an even 128
bytes]