Computer Terminology

A URL, or Universal Resource Locator (also known as a URI, a Uniform Resource Identifier) is a string of characters which is used to identify or name a resource, the main purpose being to enable interaction with a representation of the resource, typically the World Wide Web.

Universal Resource Locator

The 80386 switches execution to another task in any of four cases: 1. The current task executes a JMP or CALL that refers to a TSS

descriptor.

2. The current task executes a JMP or CALL that refers to a task gate.

3. An interrupt or exception vectors to a task gate in the IDT.

4. The current task executes an IRET when the NT flag is set.

JMP, CALL, IRET, interrupts, and exceptions are all ordinary mechanisms of the 80386 that can be used in circumstances that do not require a task switch. Either the type of descriptor referenced or the NT (nested task) bit in the flag word distinguishes between the standard mechanism and the variant that causes a task switch.

To cause a task switch, a JMP or CALL instruction can refer either to a TSS descriptor or to a task gate. The effect is the same in either case: the 80386 switches to the indicated task.

An exception or interrupt causes a task switch when it vectors to a task gate in the IDT. If it vectors to an interrupt or trap gate in the IDT, a task switch does not occur. Refer to Chapter 9 for more information on the interrupt mechanism.

Whether invoked as a task or as a procedure of the interrupted task, an interrupt handler always returns control to the interrupted procedure in the interrupted task. If the NT flag is set, however, the handler is an interrupt task, and the IRET switches back to the interrupted task.

A task switching operation involves these steps:

1. Checking that the current task is allowed to switch to the designated task. Data-access privilege rules apply in the case of JMP or CALL instructions. The DPL of the TSS descriptor or task gate must be less than or equal to the maximum of CPL and the RPL of the gate selector. Exceptions, interrupts, and IRETs are permitted to switch tasks regardless of the DPL of the target task gate or TSS descriptor.
2. Checking that the TSS descriptor of the new task is marked present and has a valid limit. Any errors up to this point occur in the context of the outgoing task. Errors are restartable and can be handled in a way that is transparent to applications procedures.
3. Saving the state of the current task. The processor finds the base address of the current TSS cached in the task register. It copies the registers into the current TSS (EAX, ECX, EDX, EBX, ESP, EBP, ESI, EDI, ES, CS, SS, DS, FS, GS, and the flag register). The EIP field of the TSS points to the instruction after the one that caused the task switch.
4. Loading the task register with the selector of the incoming task's TSS descriptor, marking the incoming task's TSS descriptor as busy, and setting the TS (task switched) bit of the MSW. The selector is either the operand of a control transfer instruction or is taken from a task gate.
5. Loading the incoming task's state from its TSS and resuming execution. The registers loaded are the LDT register; the flag register; the general registers EIP, EAX, ECX, EDX, EBX, ESP, EBP, ESI, EDI; the segment registers ES, CS, SS, DS, FS, and GS; and PDBR. Any errors detected in this step occur in the context of the incoming task. To an exception handler, it appears that the first instruction of the new task has not yet executed.

Note that the state of the outgoing task is always saved when a task switch occurs. If execution of that task is resumed, it starts after the instruction that caused the task switch. The registers are restored to the values they held when the task stopped executing.

Every task switch sets the TS (task switched) bit in the MSW (machine status word). The TS flag is useful to systems software when a coprocessor (such as a numerics coprocessor) is present. The TS bit signals that the context of the coprocessor may not correspond to the current 80386 task. Chapter 11 discusses the TS bit and coprocessors in more detail.

Exception handlers that field task-switch exceptions in the incoming task (exceptions due to tests 4 thru 16 of Table 7-1) should be cautious about taking any action that might load the selector that caused the exception. Such an action will probably cause another exception, unless the exception handler first examines the selector and fixes any potential problem.

The privilege level at which execution resumes in the incoming task is neither restricted nor affected by the privilege level at which the outgoing task was executing. Because the tasks are isolated by their separate address spaces and TSSs and because privilege rules can be used to prevent improper access to a TSS, no privilege rules are needed to constrain the relation between the CPLs of the tasks. The new task begins executing at the privilege level indicated by the RPL of the CS selector value that is loaded from the TSS.

You would think the term "geek" was just invented from this modern generation, but I've known this word since the 50's. Geeks (in our minds) wore horn-rimmed glasses, had bad skin, kept to themselves and got straight A's which was uncool for even my time. Funny, those "geeks" probably ended up becoming scientists or doctors or psychiatrists which many of us use! The laugh is on us!

Bloggers started soon after 9/11. They consider themselves bright, overly intelligent and non-stoppable. The are the "new journalists" etc. of the modern generation and, take great delight in so-called "uncovering the truth" (and sometimes they do succeed.) They are taking over on-line and have their very own websites (like small diaries chatting back and forth re their ideas) You don't even really need to know that much about computers. They are also "case crackers" and love a good challenge. They are often regarded as "self-important" but many are tired of the second rate form of journalism and to be honest, many are extremely bright. They don't need editors or publishers.

Their mission ... to remake political journalism and an attempt at changing the democracy itself. To make a run around the media by becoming publishers on the internet. One blogger is Matt Druge who wired the news and gossip and broke the story about Monica Lewinsky's affair with Bill Clinton (Matt is a blogger.) They are forcing mainstream news media to follow the stories they're pushing, such as the scandal that took down Senate Majority Leader Trent Lott. Bloogers run free, while "Geeks" need proof, but both get along together (intellectual minds coming together.)

Is this good or bad? I feel (my own opinion) there is a high price to pay for such things as this and one day they will. As out of control and as mistrustful as they can be about our jouranlists, news coverage, etc., Bloggers too will succumb to their own egotistic ways and be taken over by another foreign body such as they just did.

If you are interested about "Bloogers" go to www.bloggers.com

Marcy

Electronic Spam, commonly shortened and called "Spam," is a general abuse of online messaging systems, including instant messaging, email, etc. Spam is most commonly associated with email spam and is defined as a constant stream of nearly identical emails indicating a single point, e.g. advertising.

• Spam is the abuse of electronic messaging systems to send unsolicited bulk messages indiscriminately. While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, Online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, and file sharing network spam.

  Spamming remains economically viable because advertisers have no operating costs beyond the management of their mailing lists, and it is difficult to hold senders accountable for their mass mailings. Because the barrier to entry is so low, spammers are numerous, and the volume of unsolicited mail has become very high. The costs, such as lost productivity and fraud, are borne by the public and by Internet service providers, which have been forced to add extra capacity to cope with the deluge. Spamming is widely reviled, and has been the subject of legislation in many jurisdictions.

• Electronic junk mail or junk newsgroup postings. Some people define spam even more generally as any unsolicited e-mail. However, if a long-lost brother finds your e-mail address and sends you a message, this could hardly be called spam, even though it's unsolicited. Real spam is generally e-mail advertising for some product sent to a mailing list or newsgroup.

  In addition to wasting people's time with unwanted e-mail, spam also eats up a lot of network bandwidth. Consequently, there are many organizations, as well as individuals, who have taken it upon themselves to fight spam with a variety of techniques. But because the Internet is public, there is really little that can be done to prevent spam, just as it is impossible to prevent junk mail. However, some online services have instituted policies to prevent spammers from spamming their subscribers.