ST10 STMICROELECTRONICS [STMicroelectronics], ST10 Datasheet - Page 12

• Manufacturer Part Number: ST10
• Description: 16-BIT MCU WITH 32K BYTE ROM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST10C167
V - CENTRAL PROCESSING UNIT (CPU)
The CPU includes a 4-stage instruction pipeline, a
16-bit arithmetic and logic unit (ALU) and dedi-
cated SFRs. Additional hardware has been added
for a separate multiply and divide unit, a bit-mask
generator and a barrel shifter.
Most of the ST10C167’s instructions can be exe-
cuted in one instruction cycle which requires 80ns
at 25MHz CPU clock. For example, shift and
rotate instructions are processed in one instruc-
tion cycle independent of the number of bits to be
shifted. Multiple-cycle instructions have been opti-
mized: branches are carried out in 2 cycles, 16 x
16 bit multiplication in 5 cycles and a 32/16 bit
division in 10 cycles.The jump cache reduces the
execution time of repeatedly performed jumps in a
loop, from 2 cycles to 1 cycle.
Figure 4 : CPU Block Diagram
12/65
32K Byte
on chip
ROM
32
Exec. Unit
BUSCON 0
BUSCON 1
BUSCON 2
BUSCON 3
BUSCON 4
Data Pg. Ptrs
Instr. Ptr
Instr. Reg
STKOV
STKUN
SYSCON
4-Stage
Pipeline
PSW
SP
ADDRSEL 1
ADDRSEL 2
ADDRSEL 3
ADDRSEL 4
Code Seg. Ptr.
Bit-Mask Gen.
Mul./Div.-HW
Barrel-Shift
CPU
16-Bit
MDH
MLD
ALU
CP
The CPU uses an actual register context
consisting of up to 16 Word wide GPRs physically
allocated within the on-chip RAM area. A Context
Pointer (CP) register determines the base
address of the active register bank to be accessed
by the CPU. The number of register banks is only
restricted by the available internal RAM space.
For easy parameter passing, a register bank may
overlap others.
A system stack of up to 1024 Byte is provided as a
storage for temporary data. The system stack is
allocated in the on-chip RAM area, and it is
accessed by the CPU via the stack pointer (SP)
register. Two separate SFRs, STKOV and
STKUN, are implicitly compared against the stack
pointer value upon each stack access for the
detection of a stack overflow or underflow.
Registers
General
Purpose
R15
R0
16
16
2K Byte
Internal
RAM
Bank
Bank
Bank
n
0
i