How to Choose an Anti-Virus Program

1. • 1
     Determine if your Internet Service Provider offers a free download of security or anti-virus and/or anti-spyware products. You can visit their website and go to the "help" section or call their technical support line and they will walk you through the download and installation process. Software is not "automatically" downloaded. This is a myth. Rather, you must download, put in the license key and then finish installing, updating and tweaking in order for it to function properly and protect your machine. This takes the guesswork and expense out of choosing an anti-virus program.
   • 2
     Shop around. Go to the store (can be any computer, electronics, major retailer or discount store) and compare prices. You can also shop online. Often times, if you make a purchase, the retailer may throw in anti-virus protection free with your purchase. Again, you will need to download and install the software to make it work.
   • 3
     Determine which features you need and how you will use your computer. If you use for pleasure and do not have "high speed" Internet access, you do not need the most stealthy anti-virus nor do you need an entire security suite. If you are looking for business features, however, you will want offerings of a full suite such as anti-spyware, spam filter, anti-virus and firewall. There are even some with parental controls built in so you can activate them.
   • 4
     If one anti-virus program tends to slow down your computer from what it was previously, uninstall and try a new software program.
   • 5
     If money is a problem or you do not wish to invest anything in software, go to the link in this article and download AVG free edition.
   • 6
     If you are unsure and do not wish to spend the money for a full version and software license, download a trial anti-virus version which covers you anywhere from 30 to 90 days. If at the end of the trial (or during) you find you wish to switch or do not like the performance, simply uninstall and reinstall a replacement anti-virus program.

ACPI Part 2

Power States

Global states

The ACPI specification defines the following seven states (so-called global states) for an ACPI-compliant computer-system:

• G0 (S0): Working
• G1, Sleeping subdivides into the four states S1 through S4:
  • S1: All processor caches are flushed, and the CPU(s) stop executing instructions. Power to the CPU(s) and RAM is maintained; devices that do not indicate they must remain on may be powered down.
  • S2: CPU powered off
  • S3: Commonly referred to as Standby, Sleep, or Suspend to RAM. RAM remains powered
  • S4: Hibernation or Suspend to Disk. All content of main memory is saved to non-volatile memory such as a hard drive, and is powered down.
• G2 (S5), Soft Off: G2 is almost the same as G3 Mechanical Off, but some components remain powered so the computer can "wake" from input from the keyboard, clock, modem, LAN, or USB device.
• G3, Mechanical Off: The computer's power consumption approaches close to zero, to the point that the power cord can be removed and the system is safe for dis-assembly (typically, only the real-time clock is running off its own small battery).

Furthermore, the specification defines a Legacy state: the state on an operating system which does not support ACPI. In this state, the hardware and power are not managed via ACPI, effectively disabling ACPI.

Device states

The device states D0-D3 are device-dependent:

• D0 Fully On is the operating state.
• D1 and D2 are intermediate power-states whose definition varies by device.
• D3 Off has the device powered off and unresponsive to its bus.

Processor states

The CPU power states C0-C3 are defined as follows:

• C0 is the operating state.
• C1 (often known as Halt) is a state where the processor is not executing instructions, but can return to an executing state essentially instantaneously. All ACPI-conformant processors must support this power state. Some processors, such as the Pentium 4, also support an Enhanced C1 state (C1E or Enhanced Halt State) for lower power consumption.
• C2 (often known as Stop-Clock) is a state where the processor maintains all software-visible state, but may take longer to wake up. This processor state is optional.
• C3 (often known as Sleep) is a state where the processor does not need to keep its cache coherent, but maintains other state. Some processors have variations on the C3 state (Deep Sleep, Deeper Sleep, etc.) that differ in how long it takes to wake the processor. This processor state is optional.

Performance states

While a device or processor operates (D0 and C0, respectively), it can be in one of several power-performance states. These states are implementation-dependent, but P0 is always the highest-performance state, with P1 to Pn being successively lower-performance states, up to an implementation-specific limit of n no greater than 16.
P-states have become known as SpeedStep in Intel processors

• P1 less than P0, voltage/frequency scaled
• Pn less than P(n-1), voltage/frequency scaled

Advanced Configuration and Power Interface

ACPI aims to consolidate and improve upon existing power and configuration standards for hardware devices. It provides a transition from existing standards to entirely ACPI-compliant hardware, with some ACPI operating systems already removing support for legacy hardware. With the intention of replacing Advanced Power Management, the MultiProcessor Specification and the Plug and Play BIOS Specification, the standard brings power management into operating system control, as opposed to the previous BIOS central system, which relied on platform-specific firmware to determine power management and configuration policy. The ACPI specification contains numerous related components for hardware and software programming, as well as a unified standard for device/power interaction and bus configuration. As a document that unifies many previous standards it covers many areas, for system and device builders as well as system programmers. Some software developers have trouble implementing ACPI and express concerns about the requirements that bytecode from an external source must be run by the system with full privileges. Linus Torvalds, creator of the Linux kernel, once described it as "a complete design disaster in every way", in relation to his view that "modern PCs are horrible". Microsoft Windows 98 was the first operating system with full support for ACPI, with Windows 2000, Windows XP, Windows Vista, Windows 7, eComStation, FreeBSD, NetBSD, OpenBSD, HP-UX, OpenVMS, Linux and PC versions of SunOS all having at least some support for ACPI.