mc68hc705j2 Freescale Semiconductor, Inc, mc68hc705j2 Datasheet - Page 53

• Manufacturer Part Number: mc68hc705j2
• Description: 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

6.1 Memory Map
6.1.1 Input/Output Section
6.1.2 RAM
MC68HC705J2
This section describes the organization of the on-chip memory.
The CPU can address 4 Kbytes of memory space.
normally advances one address at a time through the memory, reading the
program instructions and data.
program instructions, fixed data, user-defined vectors, and service routines.
The RAM portion of memory holds variable data.
memory-mapped so that the CPU can access their locations in the same way
that it accesses all other memory locations.
Figure 6-1 is a memory map of the MCU. Figure 6-2 is a more detailed memory
map of the 32-byte I/O register section.
The first 32 addresses of the memory space, $0000–$001F, are defined as the
I/O section. These are the addresses of the I/O control registers, I/O status
registers, and I/O data registers.
The MCU has 112 bytes of fully static read/write memory for storage of variable
and temporary data during program execution. RAM addresses $00C0–$00FF
serve as the stack. The CPU uses the stack to save CPU register contents
before processing an interrupt or subroutine call. The stack pointer decrements
during pushes and increments during pulls.
Be careful if using the stack addresses ($00C0–$00FF) for data
storage or as a temporary work area. The CPU may overwrite
data in the stack during a subroutine or interrupt.
SECTION 6
MEMORY
M E M O R Y
The EPROM portion of memory holds the
N O T E
The program counter
I/O registers are
MOTOROLA
6-1