MC68HC711EA9 View Datasheet(PDF) - Freescale Semiconductor

Part Name

Description

Manufacturer

MC68HC711EA9

8-Bit Microcontrollers

Freescale Semiconductor 

Freescale Semiconductor, Inc.

3.2.3 Index Register Y (IY)

The 16-bit IY register performs an indexed mode function similar to that of the IX register. However,

most instructions using the IY register require an extra byte of machine code and an extra cycle of ex-

ecution time because of the way the opcode map is implemented.

3.2.4 Stack Pointer (SP)

The M68HC11 CPU has an automatic program stack. This stack can be located anywhere in the ad-

dress space and can be any size up to the amount of memory available in the system. Normally the SP

is initialized by one of the first instructions in an application program. The stack is configured as a data

structure that grows downward from high memory to low memory. Each time a new byte is pushed onto

the stack, the SP is decremented. Each time a byte is pulled from the stack, the SP is incremented. At

any given time, the SP holds the 16-bit address of the next free location in the stack.

3.2.5 Program Counter (PC)

The program counter, a 16-bit register, contains the address of the next instruction to be executed. After

reset, the program counter is initialized from one of six possible vectors, depending on operating mode

and the cause of reset.

3.2.6 Condition Code Register (CCR)

This 8-bit register contains five condition code indicators (C, V, Z, N, and H), two interrupt masking bits,

(IRQ and XIRQ) and a stop disable bit (S). In the M68HC11 CPU, condition codes are automatically

updated by most instructions. For example, load accumulator A (LDAA) and store accumulator A

(STAA) instructions automatically set or clear the N, Z, and V condition code flags.

3.2.7 Addressing Modes

Six addressing modes can be used to access memory: immediate, direct, extended, indexed, inherent,

and relative. These modes are not detailed in this manual. For a complete description of the CPU reg-

isters, addressing modes, and instruction set refer to the M68HC11 Reference Manual (M68HC11RM/

AD).

MC68HC11EA9

MC68HC11EA9TS/D

For More Information On This Product,

9

Go to: www.freescale.com

Share Link: