MC68HC08JB1 Datasheet, PDF (45/216 Pages) Motorola, Inc – Microcontrollers

Technical Data — MC68HC08JB1
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
3.2 Introduction
This section describes the 128 bytes of RAM.
3.3 Functional Description
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.
NOTE: For correct operation, the stack pointer must point only to RAM
locations.
Before processing an interrupt, the CPU uses five bytes of the stack to
save the contents of the CPU registers.
NOTE: For M6805 Family 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.
NOTE:
Be careful when using nested subroutines. The CPU may overwrite data
in the RAM during a subroutine or during the interrupt stacking
operation.
MC68HC08JB1 — Rev. 2.1
Freescale Semiconductor
Technical Data
45