Rainbow Electronics ATtiny12 - Manual (Page 10)

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ATtiny11/12
1006C–09/01
OR and all other operations between two registers or on a single register apply to the
entire register file.
Registers 30 and 31 form a 16-bit pointer (the Z-pointer) which is used for indirect Flash
memory and register file access. When the register file is accessed, the contents of R31
are discarded by the CPU.
ALU – Arithmetic Logic
Unit The high-performance AVR ALU operates in direct connection with all the 32 general-
purpose working registers. Within a single clock cycle, ALU operations between regis-
ters in the register file are executed. The ALU operations are divided into three main
categories – arithmetic, logic and bit-functions. Some microcontrollers in the AVR prod-
uct family feature a hardware multiplier in the arithmetic part of the ALU.
Flash Program Memory The ATtiny11/12 contains 1K bytes on-chip Flash memory for program storage. Since
all instructions are single 16-bit words, the Flash is organized as 512 x 16 words. The
Flash memory has an endurance of at least 1000 write/erase cycles.
The ATtiny11/12 Program Counter is 9 bits wide, thus addressing the 512 words Flash
program memory.
See page 44 for a detailed description on Flash memory programming.
Program and Data
Addressing Modes The ATtiny11/12 AVR RISC Microcontroller supports powerful and efficient addressing
modes. This section describes the different addressing modes supported in the
ATtiny11/12. In the figures, OP means the operation code part of the instruction word.
To simplify, not all figures show the exact location of the addressing bits.
Register Direct, Single
Register Rd Figure 8. Direct Single-register Addressing
The operand is contained in register d (Rd).