ARM Assembly Language

Fundamentals and Techniques, Second Edition

William Hohl, Christopher Hinds

• Publisher: CRC Press
• Year: 2014
• ISBN:
  9781498782678
• Edition: 2
• Topic: Computer Science
• Subtopic: Computer Science General
• Index: Computer Science

Delivering a solid introduction to assembly language and embedded systems, ARM Assembly Language: Fundamentals and Techniques, Second Edition continues to support the popular ARM7TDMI, but also addresses the latest architectures from ARM, including Cortex-A, Cortex-R, and Cortex-M processors-all of which have slightly different instruction sets, p

Chapter 1

An Overview of Computing Systems

1.1 Introduction

Most users of cellular telephones don’t stop to consider the enormous amount of effort that has gone into designing an otherwise mundane object. Lurking beneath the display, below the user’s background picture of his little boy holding a balloon, lies a board containing circuits and wires, algorithms that took decades to refine and implement, and software to make it all work seamlessly together. What exactly is happening in those circuits? How do such things actually work? Consider a modern tablet, considered a fictitious device only years ago, that displays live television, plays videos, provides satellite navigation, makes international Skype calls, acts as a personal computer, and contains just about every interface known to man (e.g., USB, Wi-Fi, Bluetooth, and Ethernet), as shown in Figure 1.1. Gigabytes of data arrive to be viewed, processed, or saved, and given the size of these hand-held devices, the burden of efficiency falls to the designers of the components that lie within them.

Figure 1.1

Handheld wireless communicator.

Underneath the screen lies a printed circuit board (PCB) with a number of individual components on it and probably at least two system-on-chips (SoCs). A SoC is nothing more than a combination of processors, memory, and graphics chips that have been fabricated in the same package to save space and power. If you further examine one of the SoCs, you will find that within it are two or three specialized microprocessors talking to graphics engines, floating-point units, energy management units, and a host of other devices used to move information from one device to another. The Texas Instruments (TI) TMS320DM355 is a good example of a modern SoC, shown in Figure 1.2.

Figure 1.2

The TMS320DM355 System-on-Chip from Texas Instruments. (From Texas Instruments. With permission.)

System-on-chip designs are becoming increasingly sophisticated, where engineers are looking to save both money and time in their designs. Imagine having to produce the next generation of our hand-held device—would it be better to reuse some of our design, which took nine months to build, or throw it out and spend another three years building yet another, different SoC? Because the time allotted to designers for new products shortens by the increasing demand, the trend in industry is to take existing designs, especially designs that have been tested and used heavily, and build new products from them. These tested designs are examples of “intellectual property”—designs and concepts that can be licensed to other companies for use in large projects. Rather than design a microprocessor from scratch, companies will take a known design, something like a Cortex-A57 from ARM, and build a complex system around it. Moreover, pieces of the project are often designed to comply with certain standards ...