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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 registers in the register file are executed. The ALU operations are divided into
three main categories - arithmetic, logical and bit-functions.
In-System Programmable Flash Program Memory
The AT90S4414/8515 contains 4K/8K bytes on-chip In-System Programmable Flash memory for program storage. Since
all instructions are 16-or 32-bit words, the Flash is organized as 2K x 16/4K x 16. The Flash memory has an endurance of
at least 1000 write/erase cycles. The AT90S4414/8515 Program Counter (PC) is 11/12 bits wide, thus addressing the
2048/4096 program memory addresses.
See page 77 for a detailed description on Flash data downloading.
See page 10 for the different program memory addressing modes.
SRAM Data Memory - Internal and External
The following figure shows how the AT90S4414/8515 SRAM Memory is organized:
Figure 8. SRAM Organization
Register File
R0
R1
R2
...
R29
R30
R31
I/O Registers
$00
$01
$02
...
$3D
$3E
$3F
AT90S4414/8515
Data Address Space
$0000
$0001
$0002
...
$001D
$001E
$001F
$0020
$0021
$0022
...
$005D
$005E
$005F
Internal SRAM
$0060
$0061
...
$015E/$025E
$015F/$025F
External SRAM
$0160/$0260
$0161/$0261
...
$FFFE
$FFFF
9
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