s3c72m9 Samsung Semiconductor, Inc., s3c72m9 Datasheet - Page 3

• Manufacturer Part Number: s3c72m9
• Description: The S3c72m5/s3c72m7/s3c72m9 Single-chip Cmos Microcontroller Has Been Designed For High Performance Using Samsung S
• Manufacturer: Samsung Semiconductor, Inc.

S3C72M5/C72M7/C72M9/P72M9 (Preliminary Spec)
PRODUCT OVERVIEW
FUNCTION OVERVIEW
SAM47 CPU
All KS57-series microcontrollers have the advanced SAM47 CPU core. The SAM47 CPU can directly address up to
32 K bytes of program memory. The arithmetic logic unit (ALU) performs 4-bit addition, subtraction, logical, and shift-
and-rotate operations in one instruction cycle and most 8-bit arithmetic and logical operations in two cycles.
CPU REGISTERS
Program Counter
A 15-bit program counter (PC) stores addresses for instruction fetches during program execution. Usually, the PC is
incremented by the number of bytes of the fetched instruction. The one instruction fetch that does not increment the
PC is the 1-byte REF instruction which references instructions stored in a look-up table in the ROM. Whenever a
reset operation or an interrupt occurs, bits PC13 through PC0 are set to the vector address.
Stack Pointer
An 8-bit stack pointer (SP) stores addresses for stack operations. The stack area is located in general-purpose data
memory bank 0. The SP is 8-bit read/writeable and SP bit 0 must always be logical zero.
During an interrupt or a subroutine call, the PC value and the PSW are written to the stack area. When the service
routine has completed, the values referenced by the stack pointer are restored. Then, the next instruction is
executed.
The stack pointer can access the stack despite data memory access enable flag status. Since the reset value of the
stack pointer is not defined in firmware, you use program code to initialize the stack pointer to 00H. This sets the
first register of the stack area to data memory location 0FFH.
PROGRAM MEMORY
In its standard configuration, the 16,384/24,576/32,768
8-bit ROM is divided into four areas:
— 16-byte area for vector addresses
— 96-byte instruction reference area
— 16-byte general-purpose area (0010–001FH)
— 16,256/24,448/32,640-byte area for general-purpose program memory
The vector address area is used mostly during reset operations and interrupts. These 16 bytes can alternately be
used as general-purpose ROM.
The REF instruction references 2 x 1-byte or 2-byte instructions stored in reference area locations 0020H–007FH.
REF can also reference three-byte instructions such as JP or CALL. So that a REF instruction can reference these
instructions, however, the JP or CALL must be shortened to a 2-byte format. To do this, JP or CALL is written to the
reference area with the format TJP or TCALL instead of the normal instruction name. Unused locations in the REF
instruction look-up area can be allocated to general-purpose use.
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