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!

All the content of this blog comes from internet. If you notice that your rights is violated, please inform us. We will corrected it promptly.

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

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.  

All the content of this blog comes from internet. If you notice that your rights is violated, please inform us. We will corrected it promptly.

Another article:Vous interroger sur vos besoins en informatique

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

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.

All the content of this blog comes from internet. If you notice that your rights is violated, please inform us. We will corrected it promptly.

Another article:Le Data Warehouse, cloches et sifflets

 

7 Data Protecting Technologies-1

Data security and fault freedom of storage are paid more and more attention. People are attaching more and more importance to developing new technologies to protect data.

1.SMART Technology
SMART, also called Self-Monitoring Analysis and Report Technology, mainly protects HD from losing data when there is some problems on the HD.    SMART drive can reduce the risk of data loss, it alarms to predict and remind thus enhancing the data security.

2.SPS
Shake  Protecting  System,    can  prevent  the  head  from  shaking  thus  enhancing  the  anti-knock characteristics of HD, avoiding damages caused by shake.

3.DFT
DFT, a kind of IBM data protecting technology, data recovery can check hard disk via using DFT program to access  the  DFT  micro  codes  in  hard  disk.  By  DFT,  users  can  conveniently  check  the  HD operation.

4.Floppy disk array technology  
Originally ‘Redundant Arrays of Inexpensive Disks’. A project at the computer science department of the University of California at Berkeley, under the direction of Professor Katz, in conjunction with Professor John Ousterhout and Professor David Patterson.  
 
The  project  is  reaching  its  culmination  with  the  implementation  of  a  prototype  disk  array  file server with a capacity of 40 GBytes and a sustained bandwidth of 80 MBytes/second. The server is being interfaced to a 1 Gb/s local area network. A new initiative, which is part of the Sequoia
2000 Project, seeks to construct a geographically distributed storage system spanning disk arrays and automated libraries of optical disks and tapes. The project will extend the interleaved storage techniques  so  successfully  applied  to  disks  to  tertiary  storage  devices.  A  key  element  of  the
research will be to develop techniques for managing latency in the I/O and network paths.  
 
The original (‘Inexpensive’) term referred to the 3.5 and 5.25 inch disks used for the first RAID system but no longer applies.  
 
The following standard RAID specifications exist:  
RAID 0   Non-redundant striped array
RAID 1   Mirrored arrays
RAID 2   Parallel array with ECC
RAID 3   Parallel array with parity
RAID 4   Striped array with parity
RAID 5   Striped array with rotating parity  

The  basic  idea  of  RAID  (Redundant  Array  of  Independent  Disks)  phpto recovery is  to  combine  multiple inexpensive disk drives into an array of disk drives to obtain performance, capacity and reliability that  exceeds  that  of  a  single  large  drive.  The  array  of  drives  appears  to  the  host  computer  as  a
single logical drive. The Mean Time Between Failure (MTBF) of the array is equal to the MTBF of an individual drive, divided by the number of drives in the array. Because of this, the MTBF of a non-redundant array (RAID 0) is too low for mission-critical systems. However, disk arrays can be made fault-tolerant by redundantly storing information in various ways.

another article:Le plaisir des yeux et des lieux pour les parties bouchons-major d'un ordinateur

Resons for Data Loss

Actually,  there  are  various  reasons  that  cause  data  loss;  software,  hardware,  factitious,  natural, intended, unintended, all may cause data loss or damage on storage devices.
 
Generally,  There  are  two  main  reasons  for  data  problem:    software  and  hardware  whose corresponding reasons are software reason and hardware reason.

1.Software reason
Virus,  format,  mis-partition,  mis-clone,  mis-operation,  photo recovery for Mac network  deletion,  power-cut  during operation all may  be  the  software  reasons.  The  symptoms  are  usually  mis-operation,  read  error, can not find or open file, report no partition, not formatted, password lost and troubled characters.
 
A:  Computer  Viruses:  some  malicious  virus  programs  will  destroy  data,  overwrite,  or  erase  the data contents.
 
B:  Mis-format:  fast  or  completely  format  partition,  thus  changing  the  file  system  form  (NTFS, FAT32) of partition.
 
C: Mis-Clone: when backing up the hard disk, mis-clone or overlay the original data on hard disk.  
 
For  these,  we  can  use  software  tools  to  recover  it.  So  called  soft  recovery  means  data  can  be recovered  by  software,  not  referring  to  hardware  fixing  operation  for  its  fault  is  not  because  of hardware failure.  
 
The following are prompts that system can not start up normally:
 
Invalid Partition Table: Invalid partition table information.
Missing Operating System: phpto recovery“55AA” mark in DOS boot sector lost or DBR corrupted.
Disk Boot Failure: System file read failure. 
Bad or missing command interpreter: Can not find command.com file or ‘COMMAND.COM’ file corrupted.

Invalid system disk: DOS boot record corrupted.
Type  the  name  of  the  command,  Interpreter:  DOS  partition  mark  in  partition  table  error  or ‘COMMAND.COM’ file lost, corrupted.
Error Loading Operating System: Main boot startup program read boot sector unsuccessfully.
Not found any active partition in HDD: Active partition mark in partition table changed as inactive
partition mark.
 
2.Hardware reason
Sometimes  data  loss  is  because  of  hardware,  data recovery such  as  bad  sector  in  hard  disk,  power  cut,  head damage, circuit panel problem, etc.
 
When your hardware has some problems, you probably will find: the speed of hardware become slow, you cannot operate successfully; you cannot read data, etc, which are most often physical bad track failures.

Correspondingly, data recovery in hardware fix is considered as hard recovery, such as memory medium damage, track damage, hard disk scrape, head damage, electric machinery damage, chip burnout and so on..
 
The  most  distinct  feature  or  difference  between  soft  recovery  and  hard  recovery  is  whether  the memory medium itself can be normally accessed by fixing or replacing parts.  

BLOG:diskknowledge

Elementary knowledge of data recovery

1.Connotation of data
Connotation  of  data  is  comprehensive,  it  includes  not  only  multi-media  files  such  as  data
documents, images, voices that stored in file system or data base, but also hardware information,
network addresses and recover deleted files network services, which are used to deposit and manage those information.  
2.The essence of data recovery  
Data  recovery  means  retrieving  lost,  deleted,  unusable  or  inaccessible  data  that  lost  for  various
reasons.
 
Data recovery not only restores lost files but also recovers corrupted data.
On  the  basis  of  different  lost  reason,  we  can  adopt  different  data  recovery  methods.  There  are
software and hardware  reasons  that  cause  data  loss,  while  we can  recover data by  software  and
hardware ways.
 
Being different from prevention retrieve pictures and backup, data recovery is the remedial measure. The best way
to insure the security of your data is prevention and backup regularly. To operate and use your data
according to the normative steps, you can reduce the danger of data loss to the lowest.
3.The scope of data recovery
There are so many forms and phenomenon on data problem, we can divide the objects or scope of
data recovery according to different symptoms.  
 
System problem
The  main  symptom  is  that  you  cannot  enter  the  system  or  the  system  is  abnormal  or  computer
closes down. There are complex reasons for this, thus we need adopt different processing methods.
Reasons for this symptom may be the key file of system is lost or corrupted, there is some bad
track  on  hard  disk,  the  hard  disk  is  damaged,  MBR  or  DBR  is  lost,  or  the  CMOS  setting  is
incorrect and so on.
 
Bad track of hard disk
There are logic and physical bad track. Logic bad track is mainly caused by incorrect operation,
and it can be restored by software. While physical bad track is caused by physical damage, which
is real damage, we can restore it by changing the partition or sector. When there is physical bad
track, you’d better backup your data for fear that the data can not be used any more because of the
bad track.
 
Partition problem
If partition can not be identified and accessed, or partition is identified as unformatted, partition
recovery tools such as Partition Table Doctor can be used to recover data.
 
Files loss
If files are lost because of recover deleted photos on Mac deletion, format or Ghost clone error, files restoring tools such as Data
Recovery Wizard can be used to recover data.
Password loss Data Recovery E-Book V1.5 If  files,  system  password,  database  or  account  is  lost,  some  special  decryption  tools  that
correspond to certain data form such as Word, Winzip can be used.
 
Files repair
For  some  reasons,  some  files  can  not  be  accessed  or  used,  or  the  contents  are  full  of  troubled
characters,  the  contents  are  changed  so  as  they  can  not  be  read.  In  this  condition,  some  special
files restoring tools can be tried to restore the files.
4.The principle of data recovery  
Data recovery is a process of finding and recovering data, in which there may be some risk, for no
all  situations  can  be  anticipated  or  prearranged. It  means  maybe  there  will  be  some  unexpected
things happen. So you need reduce the danger in data recovery to the lowest:
 
Backup all the data in your hard disk
Prevent the equipment from being damaged again
Don’t write anything to the device on which you want to recover data  
Try to get detailed information on how the data lost and the losing process
Backup the data recovered in time.