Atari 800

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ELECTRONIC DISCUSSION
The remainder
of this
section provides
a detailed
discussion
of the
functions
of the
seven
major
modules.
Central Processing
Unit
The
Central Processing Unit (CPU) PCB
contains
the 6502
CPU
(or
MPU)
chip (A303),
t^c CTIA
or GTIA
chip (A301),
the ANTIC
chip (A3a2),
tri-level
address buffers
(Z303
and
Z304),
and the
clock
generator (Z302A
and Z302B).
CPU
6502
Integrated
Circuit
The
6502
microprocessor
contains
register
flags,
interconnections,
arithmetic
logic,
and
control
logic,
all
recognized
operation
codes.
The
characteristics
of the 6502
microprocessor
ares
Byte-oriented
structure
151
opcodes
Decima'
and binary
arithmetic
modes
Seven
addressing
modes
True
indexing
Stack
pointer
Two
interrupt
levels
64K
address
range
Integral
clock
circuit
Single
+5 volt
dc
power
requirement
Figure
1-3
is an
illustration
of the
6502
pin
assignments. The
functions
of the
pins
are
explained
on the
following
pages.
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