UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 97

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

3.7.4
Figure 3-9). It is used to address the stack area when subroutine processing or interrupt processing is performed. Be sure to
write “0” in the high-order 4 bits.
(see Figures 3-10 and 3-11).
directly after reset release (before a subroutine call or interrupt acknowledgment).
The stack pointer is a 24-bit register that holds the start address of the stack area (LIFO type: 00000H to FFFFFFH) (see
The contents of the SP are decremented before a write to the stack area and incremented after a read from the stack area
The SP is accessed by dedicated instructions.
The SP contents are undefined after RESET input, and therefore the SP must always be initialized by an initialization program
Example SP initialization
MOVG SP, #0FEE0H;SP
Stack Pointer (SP)
SP
23
0FEE0H (when used from FEDFH)
Figure 3-9 Stack Pointer (SP) Format
CHAPTER 3 CPU ARCHITECTURE
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