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48 CHAPTER 2 / COMPUTER EVOLUTION AND PERFORMANCE

Software Auxiliary
systems
FPGA/ Memory (power,
ASIC cooling)

Human Diagnostic
interface Processor port

A/D D/A
conversion conversion
Electromechanical
backup and safety

Sensors Actuators

External
environment
Figure 2.13 Possible Organization of an Embedded
System
If multiple activities must be managed simultaneously, this imposes more complex
real-time constraints.
Figure 2.13, based on [KOOP96], shows in general terms an embedded system
organization. In addition to the processor and memory, there are a number of ele-
ments that differ from the typical desktop or laptop computer:
• There may be a variety of interfaces that enable the system to measure, ma-
nipulate, and otherwise interact with the external environment.
• The human interface may be as simple as a flashing light or as complicated as
real-time robotic vision.
• The diagnostic port may be used for diagnosing the system that is being
controlled—not just for diagnosing the computer.
• Special-purpose field programmable (FPGA), application specific (ASIC), or
even nondigital hardware may be used to increase performance or safety.
• Software often has a fixed function and is specific to the application.
ARM Evolution

ARM is a family of RISC-based microprocessors and microcontrollers designed by
ARM Inc., Cambridge, England.The company doesn’t make processors but instead
designs microprocessor and multicore architectures and licenses them to manufac-
turers.ARM chips are high-speed processors that are known for their small die size
and low power requirements.They are widely used in PDAs and other handheld de-
vices, including games and phones as well as a large variety of consumer products.
ARM chips are the processors in Apple’s popular iPod and iPhone devices.ARM is
probably the most widely used embedded processor architecture and indeed the
most widely used processor architecture of any kind in the world.
The origins of ARM technology can be traced back to the British-based Acorn
Computers company. In the early 1980s, Acorn was awarded a contract by the