Epson CMOS 32-Bit Single Chip Microcomputer S1C33L03 Uživatelský manuál stáhnout pdf (Strana 12)

2 REGISTERS

EPSON

S1C33 FAMILY C33 PE CORE MANUAL

2 Registers

The C33 PE Core contains 16 general-purpose registers and 8 special registers.

R15

R14

R13

R12

R11

R10

bit 31 bit 0

General-purpose registers

TTBR

bit 31

#15

#11

#10

#15

#14

#13

#12

#11

#10

bit 0

AHR

ALR

PSR

IDIR

DBBR

Special registers

Figure 2.1 Registers

2.1 General-Purpose Registers (R0–R15)

Symbol

R0–R15

Size

32 bits

Initial value

Indeterminate

General-Purpose Register

R/W

The 16 registers R0–R15 (r0–r15) are the 32-bit general-purpose registers that can be used for data manipulation,

data transfer, memory addressing, or other general purposes. The contents of all of these registers are handled as

32-bit data or addresses, so 8- or 16-bit data is sign- or zero-extended to a 32-bit quantity when it is loaded into one

of these registers depending on the instruction used. When these registers are used for address references in the C33

PE Core, 32-bit space can be accessed directly.

During initialization at power-on, the contents of the general-purpose registers are indeterminate.

2.2 Program Counter (PC)

Symbol

Size

32 bits

Initial value

Indeterminate

Program Counter

R/W

The Program Counter (hereinafter referred to as the “PC”) is a 32-bit counter for holding the address of an

instruction to be executed. More specifically, the PC value indicates the address of the next instruction to be

executed.

As the instructions in the C33 PE Core are fixed at 16 bits in length, the low-order one bit of the PC (bit 0) is always 0.

Although the C33 PE Core allows the PC to be referenced in a program, the user cannot alter it. Note, however,

that the value actually loaded into the register when a

ld.w %rd,%pc instruction (can be executed as a delayed

instruction) is executed is the “PC value for the

ld instruction + 2.”

During reset, the address written at the reset vector in the vector table indicated by TTBR is loaded into the PC, and

the processor starts executing a program from the address indicated by the PC.

During cold reset, TTBR is initialized to “0xC00000,” so that the address written at the address “0xC00000” is the

start address of the program.

Effective address

0131

Figure 2.2.1 Program Counter (PC)

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 180 181

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