Atari 800XL Service Manual

PARALLEL BUS INITFPPAPF
The
parallel
bus
Interface
(
PBI
)
provides
an
unbuffered,
direct
connection
to
the
address
data
aid
control
signals
shown
below.
It
could
be
used
to
interface
peripherals,
parallel
bus
devices
and
external
applications.
Ground
GND
1
2
EXTSEL
External
Select
Address
Output
A0
3
4
A1
Address
Output
Address
Output
A2
5
6
A3
Address
Output
Address
Output
A4
7
8
A5
Address
Output
Address
Output
A6
9
10
GND
Ground
Address
Output
A7
11
12
A8
Address
Output
Address
Output
A9
13
14
A10
Address
Output
Address
Output
All
15
16
A12
Address
Output
Address
Output
A13
17
18
A14
Address
Output
Ground
GND
19
20
A15
Address
Output
Data
Bi-Directional
D0
21
22
D1
Data
Bi-Directional
Data
Bi-Directional
D2
23
24
D3
Data
Bi-Directional
Data
Bi-Directional
D4
25
26
D5
Data
Bi-Directional
Data
Bi-Directional
D6
o.
27
o
28
g
|
D7
Data
Bi-Directional
Ground
GND
29
30
s
GND
Ground
Phase
2
Clock
Output
B02.
31
GQ
32
GND
Ground
Reserved
NC
33
34
RST
Reset
Output
Interrupt
Request
Input
IRQ
35
36
RDY
Ready
Input
Reserved
NC
37
38
EXTENB
External
Decoder
Output
Reserved
NC
39
40
REF
Refresh
Output
Column
Address
Output
CAS
41
42
GND
Ground
Math
Pack
Disable
Input
MPD
43
44
RAS
Row
Address
Strobe
Output
Ground
GND 45
46
LR/W
Latcher
Read/Write
Output
Reserved
NC
47
48
NC
Reserved
Audio
Input
AUDIO
49
50
GND
Ground
PBI
Connector
Pin
Assignments
(Looking
Into
Computer)
20

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