Continuing on down to smaller and smaller systems, we come to handheld computers. A handheld computer or PDA (Personal Digital Assistant) is a small computer that fits in a shirt pocket and carries outs a small number of functions, such as an electronic address book and memo pad. In addition, many mobile phones are hardly any different from PDAs except for the keyboard and screen. Effectively, PDAs and mobile phones have essentially merged, differing mostly in size, weight, and user interface. Nearly all of them are based on 32-bit CPUs with protected mode and run a sophisticated operating system.
The operating systems that run on these handhelds are gradually more sophisticated, with the ability to handle telephony, digital photography, and other functions. Lots of them also run third-party applications. Actually, some of them are beginning to look like a personal computer operating systems of a decade ago. One main difference between handhelds and PCs is that the former do not have multigigabyte hard disks, which changes a lot. Two of the most popular operating systems for handhelds are Symbian OS and Palm OS.
Embedded Operating SystemsEmbedded systems run on the computers that control devices that are not usually thought of as computers and which do not accept user-installed software. Typical instances are microwave ovens, TV sets, cars, DVD recorders, cell phones, MP3 players. The main property which differentiates embedded systems from handhelds is the certainty that no untrusted software will ever run on it. You cannot download new applications to your microwave oven, all the software is in ROM. This means that there is no need for protection between applications, leading to some simplification. Systems such as QNX and VxWorks are popular in this domain.
Tagspersonal computer, operating system, software
- Implementing Directories
- An Example Program Using File System Calls
- IMPLEMENTATION ISSUES
- Shared Libraries / Mapped Files
- Page Size
- The Least Recently Used (LRU) Page Replacement Algorithm
- The Not Recently Used Page Replacement Algorithm
- PAGE REPLACEMENT ALGORITHMS
- RESEARCH ON PROCESSES AND THREADS
- Process States
- Large Programming Projects
- Header Files
- SYSTEM CALLS
- Ontogeny Recapitulates Phylogeny
- The Shell
- Real-Time Operating Systems
- Multiprocessor Operating Systems
- Booting the Computer
- COMPUTER HARDWARE REVIEW
- The Fourth Generation (1980-Present) Personal Computers
- The Third Generation (1965-1980) ICs and Multiprogramming
- The Second Generation (1955-65) Transistors and Batch Systems
- The First Generation (1945-55) Vacuum Tubes
- HISTORY OF OPERATING SYSTEMS
- The Operating System as a Resource Manager
- The Operating System as an Extended Machine
- WHAT IS AN OPERATING SYSTEM?
- Introduction To Operating System