12.2 In-System Reprogrammable Flash Program Memory

The ATmega8A contains 8K bytes On-chip In-System Reprogrammable Flash memory for program storage. Since all AVR instructions are 16- or 32-bits wide, the Flash is organized as 4K x 16 bits. For software security, the Flash Program memory space is divided into two sections, Boot Program section and Application Program section.

The Flash memory has an endurance of at least 10,000 write/erase cycles. The ATmega8A Program Counter (PC) is 12 bits wide, thus addressing the 4K Program memory locations. The operation of Boot Program section and associated Boot Lock Bits for software protection are described in detail in Boot Loader Support – Read-While-Write Self-Programming. Memory Programming contains a detailed description on Flash Programming in SPI- or Parallel Programming mode.

Constant tables can be allocated within the entire Program memory address space (see the LPM – Load Program memory instruction description).

Timing diagrams for instruction fetch and execution are presented in Instruction Execution Timing.