mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 29

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

2.5 Random-Access Memory (RAM)
MC68HC908QF4 — Rev. 1.0
MOTOROLA
NOTE:
NOTE:
NOTE:
Table 2-1
.
Addresses $0080–$00FF are RAM locations. The location of the stack RAM is
programmable. The 16-bit stack pointer allows the stack to be anywhere in the
64-Kbyte memory space.
For correct operation, the stack pointer must point only to RAM locations.
Before processing an interrupt, the central processor unit (CPU) uses five bytes of
the stack to save the contents of the CPU registers.
For M6805, M146805, and M68HC05 compatibility, the H register is not stacked.
During a subroutine call, the CPU uses two bytes of the stack to store the return
address. The stack pointer decrements during pushes and increments during pulls.
Be careful when using nested subroutines. The CPU may overwrite data in the
RAM during a subroutine or during the interrupt stacking operation.
Vector Priority
Freescale Semiconductor, Inc.
Highest
Lowest
For More Information On This Product,
shows the MC68HC908QF4 reset and interrupt vectors.
Go to: www.freescale.com
Vector
IF14
IF13
IF6
IF5
IF4
IF3
IF2
IF1
—
—
↓
Table 2-1. Vector Addresses
Memory
Address
$FFFB
$FFFC
$FFFD
$FFFE
$FFE0
$FFE1
$FFF2
$FFF3
$FFF4
$FFF5
$FFF6
$FFF7
$FFFA
$FFFF
—
—
Keyboard vector (high)
Keyboard vector (low)
Not used
TIM overflow vector (high)
TIM overflow vector (low)
TIM channel 1 vector (high)
TIM channel 1 vector (low)
TIM channel 0 vector (high)
TIM channel 0 vector (low)
Not used
IRQ vector (high)
IRQ vector (low)
SWI vector (high)
SWI vector (low)
Reset vector (high)
Reset vector (low)
Random-Access Memory (RAM)
Vector
Data Sheet
Memory
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