MC68HC705J1A

Manufacturer Part NumberMC68HC705J1A
ManufacturerMotorola
MC68HC705J1A datasheet
 


Specifications of MC68HC705J1A

CaseDIP-20L  
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Page 37/162

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Addr.
Register Name
$0019
Unimplemented
$001E
Unimplemented
$001F
Reserved
Read:
COP Register
$07F0
(COPR)
Write:
See page 99.
Reset:
Read:
Mask Option Register
$07F1
(MOR)
Write:
See page 41.
Reset:
Figure 2-2. I/O Register Summary (Sheet 3 of 3)
2.5 RAM
The 64 addresses from $00C0 to $00FF serve as both the user RAM and
the stack RAM. Before processing an interrupt, the central processor
unit (CPU) uses five bytes of the stack to save the contents of the CPU
registers. During a subroutine call, the CPU uses two bytes of the stack
to store the return address. The stack pointer decrements when the CPU
stores a byte on the stack and increments when the CPU retrieves a byte
from the stack.
NOTE:
Be careful when using nested subroutines or multiple interrupt levels.
The CPU may overwrite data in the RAM during a subroutine or during
the interrupt stacking operation.
MC68HC705J1A — Rev. 4.0
MOTOROLA
Bit 7
6
5
4
R
R
R
R
SOSCD
EPMSEC OSCRES
SWAIT
Unaffected by reset
= Unimplemented
R = Reserved
Memory
Memory
3
2
1
Bit 0
R
R
R
R
COPC
0
SWPDI
PIRQ
LEVEL
COPEN
Technical Data
RAM
37