Address Registers (A0 And A1); Frame Base Register (Fb); Program Counter (Pc); Interrupt Table Register (Intb) - Renesas R8C/Tiny Series Software Manual

Chapter 1 Overview

1.3.2 Address Registers (A0 and A1)

The address registers (A0 and A1) are 16-bit registers with functions similar to those of the data regis-
ters. These registers are used for address register-based indirect addressing and address register-
based relative addressing.
For some instructions, registers A1 and A0 can be combined to configure a 32-bit address register
(A1A0).

1.3.3 Frame Base Register (FB)

The frame base register (FB) is a 16-bit register used for FB-based relative addressing.

1.3.4 Program Counter (PC)

The program counter (PC) is a 20-bit register that indicates the address of the instruction to be executed
next.

1.3.5 Interrupt Table Register (INTB)

The interrupt table register (INTB) is a 20-bit register that indicates the initial address of the interrupt
vector table.

1.3.6 User Stack Pointer (USP) and Interrupt Stack Pointer (ISP)

There are two types of stack pointers: a user stack pointer (USP) and an interrupt stack pointer (ISP).
Each consists of 16 bits.
The stack pointer (USP/ISP) to be used can be switched with the stack pointer select flag (U flag).
The stack pointer select flag (U flag) is bit 7 of the flag register (FLG).

1.3.7 Static Base Register (SB)

The static base register (SB) is a 16-bit register used for SB-based relative addressing.

1.3.8 Flag Register (FLG)

The flag register (FLG) is an 11-bit register used as flags in one-bit units. For details on the functions of
the flags, see Section 1.4, "Flag Register (FLG)."
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1.3 Register Configuration