MC6800 Motorola, MC6800 Datasheet - Page 12

• Manufacturer Part Number: MC6800
• Description: 8-BIT MICROPROCESSING UNIT (MPU)
• Manufacturer: Motorola

1
registers available for use by the programmer
that contains the address of the ne&,,a$ilable
external push-down/pop-up
tion (address) that is conV@ieJ~t. In those applications
that is used x~i$~$?data
the lnde&&
cwuktprs
a~~{~~metic
dicates the results of an Arithmetic
and half carry from bit 3 (H). These bits of the Condition
Code Register are used as testable conditions for the condi-
tional branch instructions.
The unused bits of the Condition Code Register (b6 and b7)
are ones.
(16 bits) register that points to the curre~~,”w~$m
random access Read/Write,,,%b*~.#’’that
require storage of inf@~atidB’
lost, the stack muskl~~~~volatile.
Negative (N), Zero (Z), Overflow (V), Carry from bit 7 (C),
The
Aq~$#~ators
Condition
Program Counter – The program count~$&~?:’&t&o byte
Stack Pointer – The stack pon~*i~%,;&o
Index RWis~~~~~$%e index register is a two byte register
...
Address
Bus
VMA
{.. .. .
m
R/%
Data
Bus
BA
M PU has three
@l
@z
;8
:$.,,,
..
..\..:+L.\:!!i,
that are used to hold operands and results from
Code Register –
&&e
*
, .:,.
logic unit (ALU).
x
x
$:.,,,
–
Addr
of memory addressing.
Fetch
~?,
@
The
FIGURE13 – HALT AND SINGLE INSTRUCTION =ECUTION FOR SYSTEM DEBUG
M
..
,.,,,
or a sixteen bit memory address for
m
XY
XY
16-bit
Bit 4 is the interrupt mask bit (l).
Instruction
MPU
x
st$~~$~fs
The condition code register in-
Exwute
MOTOROLA
In the stack when power is
registers
contains
Logic Unit operation:
\
stack is normally a
may have any loca-
,+$, ‘~,i
and thra-$,8~*@
two
(FJ$’@?~d@.
*.Y -I:,.,~~>
location in an
byte register
8-bit
address.
,
,$
:.~~>),
.,
that
ac-
12
Semiconductor
))
{1
15
FIGURE14 – PROGRAMMING MODEL OF
THE MICROPROCESSINGUNIT
Pc
SP
Instruction
Fetch
7
m
Products Inc.
llt
/
w
INZVC
II -
r
Execute
Instruction
0
o
Carrv
Accumulator
Program
Condition
Half
Accumulator
Registar
;:::t
Index
Overflow
zero
Stack
Carrv
(From
Register
Pointer
Counter
Code
(From
Bit 7)
B
A
Bit 3)
-.
—.