PEER TO PEER LANs

PEER TO PEER LANs

• Peer-to peer networks have become more popular as the software became more reliable and personal computers became more powerful computers became became more powerful.


• Peer to peer means computer to computer. In a peer to peer network, any computer can access any other computer to which it is connected and has been granted access rights. Essentially, every computer functional as both a server ans a client.


• Peer to peer network can be as small as two computers, or as large as hundreds of units.


• They may or may not use a LAN card or netwok interface card. For more then two stations, or when higher data transfer speeds are desired, NICs should be used.


• Peer to peer network are more common in small offices or whitin a department in a large organization.


• The advantage of peer to peer network is that you don't have to dedicate a computer to be a file server.


• Most peer to peer networks allow you to share practically any device attached to any computer.


• The potential disadvantages  to a peer to peer network are the there is typically less security and less control.

UPER MEMORY AREA (UMA) and Use .

UPER MEMORY AREA (UMA)

The term Uper Memory Area (UMA ) describe the reserved 384K at the top of the first megabyte of system memory on a PC/XT and the the first megabyte on a AT-type system. This memory has the address from A0000 through FFFFF.

The first 128k after conventional memory is called video RAM. It is reserved for use by video adapter. When text and graphics are displayed on-screen, the elecronics impulses that contain their images. reside in this space. Video RAM is allotted the address range from A0000-BFFFF.

The next 128K is reserved for the adapter BIOS that reside in read-only memory chips on some adapter board plugged into the bus slot. Most VGA-compatible video adapter use the first 32K of this area for their on-board BIOS, The rest can be used by any other adapters installed. Many network adapter also use this area for speacial purpose RAM called Shared Memory. Adapter ROM and special purpose RAM is allotted the address range from C0000-DFFFF.

The last 128K of memory is reserved for mother board BIOS, Whisch is stored in red-only RAM chips or ROM. The POST - Power-on self test and bootstratp loader, which handles your system at bootup until the operating system takes over, alsoreside in this space. MOST systems only use the last 64K of this space, leaving the first 64K or more free for re-mapping with memory managers. Some system also include the CMOS Setu program in this area. The motherboard BIOS is allotted the range from EOOOO-FFFFF

What is base memory / conventional memory

Q . What is base memory or conventional memory ?

The original PC/XT type system was designed to use 1 M of

memory workspace sometimes called RAM . This !m of RAM is divided into

several section. Some of which have uses. DOS can read and write to entire

megabyte, but can manage the loading of program only in the portion of ram

space called conventional memory. which at time the first PC was introduced

was 512k. The other 512K was reserved for use by the system itself, including

the motherboard and adapter  boards plugged into system slot.

IBM decided sfter introducing the system that only 384K was

needs for these reserved uses, and the company began marketing PCs with

640K of user memory. Thus, 640K became the standard for memory that can

be used by dos for running programs, and is often termed the 640K memory

barrier. The remaining memory after 640K was reserved for use by the

graphics board, other adapters, and the mother board ROM BIOS.

What is Memory Bank ?

Q. What is memory bank .

A memory bank is the smallest amount of memory that can be

addressed by processor at one time and usually corresponds to the

data bus width of the processor. Memory chip are organised in a bank

on mother board and memory cards. In order to add memory to

system, it is necessary to know the bank layout.

Laser Printer principal

How Laser Printer work

When we give a print command to printer , print process data is received by printer then laser printer start a print job in a sequence.

1. Printer apply a positive electrical charge to the drum unit.

2. The laser system ‘writes’ the page image onto the drum with a negative charge and creating an electric “virtual negative” of the image.

3.The drum unit rotates, and as the image is written on it, it picks up toner, the laser printer equivalent of ink. The toner is positively charged, and so it sticks to the image that the laser drew. The paper presses against the drum, and receives the toner image.

4.When the paper first picks up the toner, the image is not set. Toner is a dry, dusty material, and it the electric charge cannot hold it strongly to the paper. In order to make the image permanent, the paper runs through the fuser, which heats it, and melts the toner onto the page. The paper exits the printer, and you have your print out.

The Picture image given below clearly show layout to that how a laser printer works is working :

BIOS

BIOS :-          BIOS stand for Basic Input Output System. It is the low - level

system software that reside on a Read Only Memory (ROM) chip in the PC.

The BIOS programs is a set of routines for dealing with input / oputput device

such as keyboard, display, disks and serial ports , parallel ports. Programs

can access thess devices by calling the BIOS routines and need not be aware

of differences between machines that could the way input/output is

performed. Thus, BIOS enable various to access the PC's hardware.

PC Motherboard

Motherboard :

The most important component in a PC system ist the motherboard. It

contain the CPU, math proccessorr, system clock, ROM with the system BIOS

routines, RAM , keyboard controller, logic that relates to i/o operation and

much more electronic. All electronics component may not mounted be on a

single motherboard . Instead the may be located on an expansion board or

an adapter card plugged into a slot. Some system use a passive design that

incorporates the entire system circuitry into a single motherboard. The

motherboard is essentially a complete motherboard that is degigned to plug

into a slot. The motherboard concept allows the entire system to be easily

upgraded by changing one or more cards.

A typical motherboard has several options that reflects the

hardware configuration by setting the onboard switches or jumpers. Then

setting is through the SETUP utility and stored in CMOS RAM.