Atari 800XL Service Manual

Graphic Television Interface
Adaptor (GTIA)
The
GTIA
interfaces
with
the ANTIC
processor
on one
side
and
with
the video
summation
circuitry
on
the other.
Its
primary
task
is to generate
color and
luminance
signals
from
the bit
stream it
receives
from
the
ANTIC
Display
Processor.
It also
processes
the
Function
keys, provides
the
keyboard
“beep"
via the TV
speaker
and
monitors
controller
Trigger
lines.
Address
Bus A1
1
•
Address
Bus
A$
2
Ground
VSS
3
Data
Bus
D3
4
Data Bus
D2
5
Data
Bus
D1
6
Data Bus
DO
7
Trigger
0
T0
8
Trigger 1
T1
9
Trigger
2
T2
10
Trigger
3
T3
11
Option
S0
12
Start
SI
13
Select
S2
14
Keyboard
Click
S3
15
PAL
Color Delay
PAL
16
Color
Delay
CADd
17
Alphanum.
Data
0
AN0
18
Alphanum.
Data 1
AN1
19
Alphanum.
Data 2
AN2
20
40
A2
Address
Bus
39
A3
Address
Bus
38
A4
Address
Bus
37
D4
Data
Bus
36
D5
Data
Bus
35
D6
Data
Bus
34
D7
Data
Bus
33
R/¥
Read/Write
32
US'
Chip
Select 1
31
LUM
3 Luminance
Line
30
02
Phase
2 Input
29
F0O
Clock Out
28
OSC
Oscillator
Input
27
VCC
Power
26
TOUT HALT
25
CSYNC
Output
Sync.
24
LUM 2
Luminance
2 Output
23
LUM 1 Luminance
1
Output
22
|
LUM
0
Luminance
0
Output
21
!
COL
Color
GTIA
12

Atari 800XL Specifications

General

Manufacturer	Atari
Type	Home computer
Release year	1983
CPU	MOS Technology 6502C
RAM	64 KB
ROM	24 KB
Operating System	Atari OS
CPU Speed	1.79 MHz (NTSC) / 1.77 MHz (PAL)
Graphics	ANTIC and GTIA chips
Display resolution	160×192 to 320×192 pixels
Sound	POKEY chip
Storage	Cassette tape, floppy disk
Ports	Serial, parallel, monitor, joystick ports