Dedicated Registers - Fujitsu MB90895 Series Hardware Manual

3.2

Dedicated Registers

The CPU has the following dedicated registers.
• Accumulator
• User stack pointer
• System stack pointer
• Processor status
• Program counter
• Direct page register
• Bank registers (program bank register, data bank register, user stack bank register,
system stack bank register, additional data bank register)
I Configuration of Dedicated Registers
AH
Figure 3.2-1 Configuration of Dedicated Registers
: Accumulator (A)
AL
They are two 16-bit registers for calculation.
Consecutively used the registers can be used as 32-bit register.
USP
: User stack pointer (USP)
It is a 16-bit pointer for user stack address.
SSP : System stack pointer (SSP)
It is a 16-bit pointer for system stack address.
PS
: Processor status (PS)
It is a 16-bit register for system status.
PC
: Program counter (PC)
It is a 16-bit register for stored position of current instruction.
: Direct page register (DPR)
DPR
It sets bit 8 to bit 15 in address 24-bit, when executing the instruction
by abbreviated direct addressing. It is a 8-bit register.
PCB : Program bank register (PCB)
It is a 8-bit register for program space.
DTB : Data bank register (DTB)
It is a 8-bit register for data space.
USB : User stack bank register (USB)
It is a 8-bit register for user stack bank space.
SSB
: System stack bank register (SSB)
It is a 8-bit register for system stack bank space.
ADB
: Additional data bank register (ADB)
It is a 8-bit register for additional space.
8 bits
16 bits
32 bits
CHAPTER 3 CPU
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