The central processing unit (CPU) is the brain of a computer. It handles all calculations on the system by performing one arithmetic calculation at a time: addition, subtraction, multiplication, or division. The Atmega128® is a micro-controller unit which utilizes speeds of roughly 1 million instructions per second (MIPS) per megahertz (MHz) of clock speed. This means that when running at 1.0MHz, the chip can calculate roughly one million arithmetic solutions every single second.
Beyond its raw clock speed, a CPU is nothing without its memory. Without an ability to store the data calculated, the solutions would be instantly lost. The Atmega128® contains 128 kilobytes of onboard flash memory, and in addition to this, it contains four kilobytes of electronic erasable programmable read-only memory (EEPROM). EEPROM stores the binary input output system (BIOS) information for the computer, to which the chip is attached. The BIOS acts as a low-level operating system, controlling the hardware connected to the system.
The Atmega128® attaches to the motherboard in the computer system. If the CPU is the brain of the system, the motherboard is the spine: all components of the computer system connect with it. The Atmega128® connects to the motherboard via a 64-pin connection. This means that the Atmega128® is only compatible with motherboards that support this 64-pin connection.
As with all electronic devices, the Atmega128® requires a steady influx of power to operate. It runs at a voltage of 4.5 to 5.5 volts. The power supply on the computer provides this power, and the information set in the system BIOS stored on the EEPROM of the CPU chip sets the specific value of voltage.
The maximum operating frequency of the Atmega128® microprocessor is 16MHz. Again, the specific speed of the chip is typically set through the BIOS of the unit. In general, the faster a chip runs, the more power and heat it produces. At the full 16MHz speed, the Atmega128® will be capable of executing 16 million instructions per second.
In addition to requiring a specific level of voltage, each CPU chip has a specific operating temperature. Temperatures lower than the minimum will prevent electronic signals from flowing through the chip and temperatures higher than the maximum will distort the chip itself, making it impossible for signals to pass. The range of the Atmega128® is from -40 to 85 degrees Celsius (-40 to 185 Fahrenheit). However, as with all electronics, running more towards the lower end of that scale will prolong the useful life of the chip.