Microchip Technology megaAVR 0 Series Manual page 51

Figure 7-1. AVR CPU Architecture
Stack
Pointer
STATUS
Register
The Arithmetic Logic Unit (ALU) supports arithmetic and logic operations between registers or between a
constant and a register. Single-register operations can also be executed in the ALU. After an arithmetic
operation, the status register is updated to reflect information about the result of the operation.
The ALU is directly connected to the fast-access register file. The 32 8-bit general purpose working
registers all have single clock cycle access time. This allows single-cycle arithmetic logic unit operation
between registers or between a register and an immediate operand. Six of the 32 registers can be used
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2018 Microchip Technology Inc.
Register file
R31 (ZH) R30 (ZL)
R29 (YH) R28 (YL)
R27 (XH) R26 (XL)
R25 R24
R23 R22
R21 R20
R19 R18
R17 R16
R15 R14
R13 R12
R11 R10
R9 R8
R7 R6
R5 R4
R3 R2
R1 R0
ALU
Datasheet Preliminary
®
megaAVR 0-Series
AVR CPU
Program
Counter
Flash Program
Memory
Instruction
Register
Instruction
Decode
Data Memory
DS40002015A-page 51