Datasheet

FS98O22
Rev. 1.6 17/146
Table 1-4 FS98O22 CPU core block diagram description table
Items Sub Items Description
Registers
Program Counter This Register plays an important role in all the CPU working
cycle. It records the pointer of the instruction that the CPU
processes every cycle in the Program Memory. In a general
CPU cycle, Program Counter pushes the Program Memory
Address (12bits), instruction pointer, into the Program Memory
and then increments for the next cycle.
Stack Register Stack Register is used for recording the program return
instruction pointer. When the program calls function, Program
Counter will push the instruction pointer into the Stack
Register. After finish this function, Stack Register pushes the
instruction pointer back to the Program Counter to resume the
original program process.
Instruction Register After Program Counter pushes the instruction pointer
(Program Memory Address) into the Program Memory,
Program Memory pushes the Program Memory Data (16bits),
instruction, into Instruction Register for reference.
FS98O22 instruction has 16 bits, and contains 3 kinds of
information as Direct Address, Direct Data and Control
Information.
CPU could push the Direct Data into Work Register or do
some process for the register stored in the Data Memory
pointed by the Direct Address by Control Information.
z Direct Address (8bits)
It is the Data Memory Address. CPU can use this
address to process the Data Memory.
z Direct Data (8bits)
It is the value which CPU used for processing Work
Register by the ALU (arithmetic and logic unit).
z Control Information
It records the information for the ALU to process.
Instruction Decoder Instruction Register pushes the Control Information to the
Instruction Decoder to decode and then sends the decoded
information to related registers.
File Select Register In FS98O22 Instruction Sets, FSR (File Select Register) is
used for indirect data process. User could fill the FSR with the
Data Memory Address of some register, and then process this
register by IND Register. CPU will fill the IND Register with the
data address in the Data Memory as FSR.
Work Register Work Register is used for buffering the data which is stored in
some memory address of Data Memory.
Status Register While CPU processes some register data by ALU, the following
status may change as follows: PD, TO, DC, C and Z. Please
refer to Section 3.3.2 for detailed introduction.
Memory
Program Memory FS98O22 has an embedded 4k bytes OTP (One Time
Programmable) ROM as Program Memory. Because the
OPCODE of the instruction is 16 bits, user could program 4k
instructions in FS98O22 at most.
Program Memory Address Bus is 12 bits, and the Data Bus is
16bits.
Data Memory FS98O22 has an embedded 256 bytes SRAM as Data Memory.
The Data Memory Address Bus is 8 bits, and Data Bus is 8 bits.
FORTUNE'
Properties
For Reference Only