9/15 Reading Notes: Computer Software

"Introduction to Linux: A Hands on Guide"

UNIX
30 years ago each computers were massive and each one ran a different operating system. Bell Labs created UNIX, an operating system which was written in C programming language instead of assembly code and had the ability to recycle code.

Importance of code recycling-up until the creation of UNIX,each computer system was written in a code developed for that one system. UNIX only needed a kernel of that code. With the kernel as a base for UNIX, developers could create a system that ran on may types of hardware,

Probs with early UNIX- large environments with mainframes and minicomputers (PC microcomputer) in an academic, gov't or corporate setting. UNIX not free, also very slow, so users tended to use other systems.

LINUX
Created by Linus Torvalds-wanted to get UNIX on PC. Goal-to have a free system that was compliant with UNIX.
Now-to make Linux more user-friendly and to make the switch less jarring, user interface had been added , compatability with MS office applications.

Open Source
Programmer lead maturation of code. Author's opinion-open source more flexible and a better quality than commercial software, b/c more people have tested it and troubleshot its problems.

Other open source initiatives:
SAMBA-reverse engineering of the Server Message Block (SMB)/Common Internet File System (CIFS) protocol used for file and print serving on PC related machines.
Apache HTTP-runs on UNIX.

Linux Cons
Myriad of Linux options-anyone can create a code. Sometimes overwhelming to look through.
Some still consider it harder to use than Mac OS or MS Windows.
Trustworthiness-where does code come from?

Linux and GNU
Linux is based on GNU tools (GNU is not UNIX)
GNU tools are open source

* The Linux kernel is not part of the GNU project but uses same license as GNU software. Lots of utilities and tools are taken from GNU. Some argue system should be named GNU/Linux.

Mac OS X
First Introduced in 1999, Descendant of NEXTSTEP
Darwin major part of Mac OS X, has incorporated a lot of open source software (GNU tools,Apache, SAMBA).
Darwin runs on PC and x86 platforms. Can build a kernel that combines both platforms.
GNU-Darwin Project

Mac OS X Software layers:
Application Environments
Application Services JRE
Core Services JVM
Kernel
Hardware, Open Firmware, Bootloader

*XNU-the kernel
XNU based on Mach. Mach responsible for things such as:protected memory, virtual memory management and kernel debugging support.

BSD-responsible for things such as-firewall, user IDs, basic security policies.
I/O-Power management, device stacking etc. Uses C++.

"An Update on the Windows Roadmap"
Basically a letter responding to customer concerns over the switch from Microsoft XP to Vista. Message board responses centered around whether Vista was a step up from XP or just a cleaned up version of XP with a new name.