Tuesday, December 28, 2010

Basic Hardware Skills You Should Have

First, identify the parts on the front of an assembled computer ...

• Monitor
• Keyboard
• Mouse
• CPU
• Floppy Drive, CDROM Drive
• Power, Reset Buttons


Identify what you have

What type and speed of Processor?

How much RAM?
How big hard drive?
Special boards or interfaces?
Are there network, bios, or other settings we should record?
Next, identify all the input/output ports on the back ...

Compare connectors, features, older vs. newer, male vs female ...

Keyboard (AT, PS/2, USB)
Mouse (Serial, PS/2, USB)
Modem (RJ11 telephone jack)
Serial
USB
Parallel (DB25)
SCSI
Firewire
Sound In/Out
Video In/Out
Monitor (VGA)
Game Paddle
Other?

Clean the Mouse (Does not apply to optical mice!)

There is nothing more frustrating than a flakey mouse. Think of it as an upside-down trackball. Remove the ball from inside -- use 2 hands and twist. It can be washed with plain, soapy water. Rinse and dry thoroughly. Do not reinstall it until it is completely dry. Use “canned air” to remove dust from the socket  Internal contacts can be cleaned with Q-TIP/swap and alcohol. Use very small amount, do not wet insides.


Clean the Outside of your Computer

Canned air and vacuum. Damp cloth with plain water and a small amount of mild soap. Do NOT GET ANY ELECTRONIC PARTS WET! Use a Q-TIP with Isopropyl Alcohol to remove sticky or stubborn dirt -- be careful not to spill alcohol on electronics!

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Post Reproduced from: http://makeadisk.blog.com/2010/12/29/basic-hardware-skills-you-should-have/ 

Tuesday, December 7, 2010

Main technical specification and parameter of hard disk-1

Capacity
We can see the capacity in two aspects: the total capacity and the capacity of one disk. [Paid Recommendations^^: Using Mac photo recovery to recover your lost photos.] The whole capacity is made up of each disk capacity.  
If we increase the disk capacity, we would not only improve the disk capacity, improve the speed of transmission, but also cut the cost down.
 
Rotate speed.
Rotate speed is the speed disk rotate. It is measured by RPM (Round Per Minute).The rotate speed of IDE hard disk are 5400RPM, 7200RPM etc.
 
Average Seek Time
The average seek time gives a good measure of the speed of the drive in a multi-user environment where successive read/write request are largely uncorrelated.
Ten ms is common for a hard disk and 200 ms for an eight-speed CD-ROM.
 
Average Latency
The hard disk platters are spinning around at high speed, and the spin speed is not synchronized to the process that moves the read/write heads to the correct cylinder on a random access on the hard disk. recover photos Therefore, at the time that the heads arrive at the correct cylinder, the actual sector that is
needed may be anywhere. After the actuator assembly has completed its seek to the correct track, the drive must wait for the correct sector to come around to where the read/write heads are located. This time is called latency. Latency is directly related to the spindle speed of the drive and such is
influenced  solely  by  the  drive's  spindle  characteristics.  This  operation  page  discussing  spindle speeds also contains information relevant to latency.
 
Conceptually, latency is rather simple to understand; it is also easy to calculate. The faster the disk is spinning, the quicker the correct sector will rotate under the heads, and the lower latency will be. Sometimes the sector will be at just the right spot when the seek is completed, and the latency for
that access will be close to zero. Sometimes the needed sector will have just passed the head and in  this  "worst  case",  a  full  rotation  will  be  needed  before  the  sector  can  be  read.  On  average, latency will be half the time it takes for a full rotation of the disk.  

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Another article:Vous interroger sur vos besoins en informatique

Monday, December 6, 2010

History of hard disk development

The hard disk drive has short and fascinating history.   In 24 years it evolved from a monstrosity with fifty two-foot diameter disks holding five MBytes (5,000,000 bytes) of data to today's drives measuring 3 /12 inches wide and an inch high (and smaller) holding 400 GBytes (400,000,000,000 bytes/characters).   Here, then, is the short history of this marvelous device.

Before  the  disk  drive  there  were  drums...  [Paid Recommendations^^: Using Mac photo recovery to recover your lost photos.] In  1950  Engineering  Research  Associates  of Minneapolis  built  the  first  commercial  magnetic  drum  storage  unit  for  the  U.S.  Navy,  the  ERA 110. It could store one million bits of data and retrieve a word in 5 thousandths of a second..
 
In 1956 IBM invented the first computer disk storage system, the 305 RAMAC (Random Access Method of Accounting and Control).   This system could store five MBytes.   It had fifty, 24-inch diameter disks!
 
By 1961 IBM had invented the first disk drive with air bearing heads and in 1963 they introduced the removable disk pack drive.
 
In  1970  the  eight  inch  floppy  disk  drive  was  introduced  by  IBM.   My  first  floppy  drives  were made by Shugart who was one of the "dirty dozen" who left IBM to start their own companies.   In 1981  two  Shugart  8  inch  floppy  drives  with  enclosure  and  power  supply  cost  me  about
$350.00.   They were for my second computer.   My first computer had no drives at all.
 
In  1973  IBM shipped the  model 3340  Winchester  sealed hard disk drive,  the  predecessor  of  all current hard disk drives.   The 3340 had two spindles each with a capacity of 30 MBytes, and the term "30/30 Winchester" was thus coined.
 
In  1980,  Seagate  Technology  introduced  the  first  hard  disk  drive  for  microcomputers,  the ST506.  [Paid Recommendations^^: Using photo recovery to recover your lost photos.] It  was  a  full  height  (twice  as  high  as  most  current  5  1/4"  drives)  5  1/4"  drive,  with  a stepper  motor,  and  held  5  Mbytes.   My  first  hard  disk  drive  was  an  ST506. I  cannot  remember exactly how much it cost, but it plus its enclosure, etc. was well over a thousand dollars. It took me three years to fill the drive.   Also, in 1980 Phillips introduced the first optical laser drive.   In the  early  80's,  the  first  5  1/4"  hard  disks  with  voice  coil  actuators  (more  on  this  later)  started shipping  in  volume,  but  stepper  motor  drives  continued  in  production  into  the  early  1990's. In 1981, Sony shipped the first 3 1/2" floppy drives.
 
In 1983 Rodime made the first 3.5 inch rigid disk drive. The first CD-ROM drives were shipped in 1984, and "Grolier's Electronic Encyclopedia," followed in 1985. The 3 1/2" IDE drive started its existence as a drive on a plug-in expansion board, or "hard card." The hard card included the drive on the controller which, in turn, evolved into Integrated Device Electronics (IDE) hard disk drive, where the controller became incorporated into the printed circuit on the bottom of the hard disk drive. Quantum made the first hard card in 1985.
 
In 1986 the first 3 /12" hard disks with voice coil actuators were introduced by Conner in volume, but  half  (1.6")  and  full  height  5  1/4"  drives  persisted  for  several  years.   In  1988  Conner introduced the first one inch high 3 1/2" hard disk drives.   In the same year PrairieTek shipped the
first 2 1/2" hard disks.
 
In 1997 Seagate introduced the first 7,200 RPM, Ultra ATA hard disk drive for desktop computers and in February of this year they introduced the first 15,000 RPM hard disk drive,  the  Cheetah X15.   Milestones for IDE DMA, ATA/33, and ATA/66 drives follow:
 
1994 DMA, Mode 2 at 16.6 MB/s  
1997 Ultra ATA/33 at 33.3 MB/s  
1999 Ultra ATA/66 at 66.6 MB/s  
 
6/20/00   IBM triples the capacity of the world's smallest hard disk drive.   This drive holds one gigabyte on a disk which is the size of an American quarter.   The world's first gigabyte-capacity disk drive, the IBM 3380, introduced in 1980, was the size of a refrigerator, weighed 550 pounds (about 250 kg), and had a price tag of $40,000.

Another article:http://repaireordinateur.blogspot.com/2010/12/connexion-composants-de-votre.html

Friday, December 3, 2010

7 Data Protecting Technologies-2

5.SAN
SAN, called Storage Area Network or Network behind servers, is specialized, high speed network attaching servers and storage devices. A SAN allows "any to any" connection across the network, using  interconnect  elements  such  as  routers,  gateways,  hubs  and  swithes.  [Paid Recommendations^^: Using Mac photo recovery to recover your lost photos.] It  eliminates the traditional  dedicated  connection  between  a  server  and  storage,  and  concept  that  the  server effectively "owns and manages" the storage devices. It also eliminates any restriction to amount of data that a server can access, currently limited by the number of storage devices, which can be attached to the individual server. Instead, a SAN introduces the flexibility of networking to enable one  server  or  many  heterogeneous  servers  to  share  a  common  storage "utility",  which  may comprise many storage devices, including disk, tape, and optical storage. And, the storage utility may be located far from the servers which use it.

6.NAS
NAS is Network Attached Storage. It can store the quick-increased information.Backup means to prepare a spare copy of a file, file system, or other resource for use in the event of  failure  or  loss  of  the  original.  This  essential  precaution  is  neglected  by  most  new  computer users until the first time they experience a disk crash or accidentally delete the only copy of the file they have been working on for the last six months. Ideally the backup copies should be kept at a different site or in a fire safe since, though your hardware may be insured against fire, the data on it is almost certainly neither insured nor easily replaced.


7.Backup
Backup in time may reduce the danger and disaster to the lowest, [Paid Recommendations^^: Using photo recovery to recover your lost photos.] thus data security can be most ensured. In different situations, there are different ways. Both backing up important data of system with hardware and backing up key information with cloning mirror data to different storage device can work well.

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Another article:Le Data Warehouse, cloches et sifflets