Atari 800XL Service Manual

6.502C CPU Microprocessor
The
6502C
CPU
microprocessor
contains
register
flags,
interconnections,
arithmetic
logic,
control
logic,
and
all
recognized
operation
codes.
The
characteristics
of
the
microprocessor
include:
*
Byte-oriented
structure
*
Decimal
and
binary
arithmetic
modes
*
Integral
clock
circuit
*
Seven
addressing
modes
*
Single
+5 volt
DC
power
requirement
*
Stack
pointer
*
Two
interrupt
levels
*
151
opcodes
*
64K
address
range
*
True
Indexing
Ground
VSS
Ready
Input
RDY
Phase
1
Clock FPH1
Interrupt
Request
IRQ
NC
Non
Maskable
Input
NMI
+5V
Power
NC
VCC
Address
Bus
AO
Address
Bus
A1
Address
Bus
A2
Address
Bus
A3
Address
Bus A4
Address
Bus
A5
Address
Bus
A6
Address
Bus
A7
Address
Bus
A8
Address
Bus A9
Address Bus A10
Address
Bus
All
V/
1
•
40
2
39
3
38
4
37
5
36
6
35
7
34
8
33
9
32
10
31
11
30
12
29
13
28
14
27
15
26
16
25
17
24
18
23
19
22
20
21
kti>
Reset
FPH2
Phase
2
Clock
SO
Set
Overflow
FPHO
Phase
0
Clock
(in)
R/¥
Read/Write
MT
HALT
Input
NC
DO
Data
Bus
D1
Data
Bus
D2
Data
Bus
D3
Data
Bus
D4
Data
Bus
D5
Data
Bus
D6
Data
Bus
D7
Data
Bus
A15
Address
Bus
A14
Address
Bus
A13
Address
Bus
A12
Address
Bus
VSS
Ground
6502C
(Modified)
10

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