Atari 400 Hardware Manual

Mixing Graphics Modes, cont.
II. PROCEDURE TO SET UP SCREEN IN MIXED MODES, cont.:
10. POKE the JUMP instruction followed by the LO byte, then the
HI byte into the Display List. The offset for the JUMP
POKE
is the last mode line # + 1, for LO byte it is + 2,
for HI byte it is + 3.
example:
(last
mode line
#
was 6 4)
REMARK POKE INSTRUCTION
JUMP POKE START
+
65,65
LO BYTE POKE START
+
6 6'
PEEK(560)
HI BYTE POKE START
+
6 7'
PEEK(561)
III. PROCEDURE TO PRINT AND PLOT IN MIXED MODES
1. If the mode line #'s of a mode on the screen fall ~ithin
the range of that mode's normal mode line #'s then use the
following procedure:
a. POKE 87 with the mode #
b. Determine the Y coordinate by counting the # of mode
lines from the top of the screen to the current
position .
c. Determine the X position in the normal manner for that
mode.
d. Depending on the mode, either PLOT and DRAWTO, or
POSITION and PRINT.
e. These steps must be done for each mode on the screen
that meets the condition in step 1.
example: MODE 1 POKE 87,1
POSITION 2,1:PRINT 1!6;"TEXT"
MODE 7 POKE 87,7
COLOR 1:PLOT 20,20:DRAWTO 30,30
MODE 2
See step 2
B -5-

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)