Minggu, 22 April 2012

TCP/IP

TCP/IP

TCP/IP adalah salah satu perangkat lunak jaringan komputer (networking software) yang terdapat dalam sistem, dan dipergunakan dalam komunikasi data dalam local area network (LAN) maupun Internet.

TCP singkatan dari transfer control protocol dan IP singkatan dari Internet Protocol. TCP/IP menjadi satu nama karena fungsinya selalu bergandengan satu sama lain dalam komunikasi data. TCP/IP saat ini dipergunakan dalam banyak jaringan komputer lokal (LAN) yang terhubung ke Internet, karena memiliki sifat:
  1. Merupakan protokol standar yang terbuka, gratis dan dikembangkan terpisah dari perangkat keras komputer tertentu. Karena itu protokol ini banyak didukung oleh vendor perangkat keras, sehingga TCP/IP merupakan pemersatu perangkat keras komputer yang beragam merk begitu juga sebagai pemersatu berbagai perangkat lunak yang beragam merk sehingga walau memakai perangkat keras dan perangkat lunak komputer yang berlainan, komputer dan komputer lainnya dapat berkomunikasi data melalui Internet.
  2. Berdiri sendiri dari perangkat keras jaringan apapun. Sifat ini memungkinkan TCP/IP bergabung dengan banyak jaringan komputer. TCP/IP bisa beroperasi melalui sebuah Ethernet, sebuah saluran dial-up, dan secara virtual melalui berbagai media fisik transmisi data.
  3. Bisa dijadikan alamat umum sehingga tiap perangkat yang memakai TCP/IP akan memiliki sebuah alamat unik dalam sebuah jaringan komputer lokal, atau dalam jaringan kumputer global seperti Internet.

Format IP :

Sebuah alamat IP berisi satu bagian network dan satu bagian host, tetapi formatnya tidak sama pada setiap alamat IP. Sejumlah bit alamat dipakai disini untuk mengidentifikasi network, dan angka dipakai untuk mengidentifikasi host, dan beragam kelas alamat IP. Ada tiga kelas utama alamat IP yaitu kelas A, B dan C.


Ketentuan kelas alamat IP :

  1. Jika bit pertama dari sebuah alamat IP adalah angka 0, ini menunjukan network kelas A. Tujuh bit berikutnya menunjukan identitas network, dan 24 bit terakhir menunjukan identitas host. Ada 128 buah network kelas , tapi didalam setiap kelas A bisa terdapat jutaan host.
  2. Jika bit pertama dari dua angka alamat IP adalah 10, ini menunjukan alamat IP network kelas B. Angka Bit pertama kelas, kemudian 24 bit berikutnya menunjukan identitas alamat network, dan 10 bit berikutnya untuk host. Ada ribuan angka network kelas B dan setiap kelas B dapat berisi ribuan host.
  3. Jika bit pertama dari tiga bit alamat IP adalah 110, ini merupakan alamat IP kelas C. Tiga bit pertama berupa alamat kelas. 21 bit berikutnya sebagai alamat network, dan 8 bit selanjutnya merupakan identitas host. Ada jutaan network kelas C, dan didalam tiap kelas C ada 254 host.

Tampaknya seperti rumit, tetapi karena adanya penulisan alamat IP memakai bilangan desimal (0-255), maka keruwetan itu tidak terlihat. Secara sederhana bisa dilihat ketentuan pemisahan kelas network seperti berikut ini
  • Kurang dari 128 adalah alamat kelas A, byte pertama adalah bilangan network, tiga byte berikutnya adalah alamat host.
  • Dari 128 sampai 191 adalah alamat kelas B, dua byte pertama sebagai alamat network, dan dua byte terakhir sebagai alamat host.
  • Dari 192 sampai 223 adalah alamat kelas C, tiga byte pertama sebagai alamat network, dan byte terakhir sebagai alamat host.

Contoh :

  1. Sebuah network memiliki alamat IP 026.104.0.19. Ini bisa ditulis juga dg 26.104.0.19. menjelaskan adanya host dengan alamat IP nomor 104.0.19 dalam network 26 yang termasuk kelas A.
  2. Alamat IP 128.66.12.1. menunjukan alamat IP host 12.1 didalam network nomor 128.66 yang termasuk kelas B.

Minggu, 15 April 2012

WAN (Wide Area Network)

WAN (Wide Area Network)

WAN Merupakan jaringan komunikasi data yang secara geografis mencakup area yang sangat luas, lingkup nasional, regional dan global dan sering menggunakan sarana fasilitas transmisi umum seperti telepon, kabel bawah laut ataupun satelit. Protokol yang digunakan dalam WAN Media yang melayani komunikasi WAN adalah termasuk dalam Physical layer dalam 7 OSI Layer. Data yang lalu-lalang di dalam media WAN tersebut diatur dengan menggunakan seperangkat aturan yang ada di dalam layer Data link dalam 7 OSI layer.

Gambaran dari sebuah WAN :

Seperangkat peraturan atau yang sering disebut dengan istilah protokol ini, mengatur bagaimana si pengirim dan penerima data dapat menggunakan media WAN tersebut secara teratur. Pembungkusan data dalam layer Data link ini sering disebut dengan enkapsulasi. Untuk itu, protokol pengatur ini sangatlah penting ditentukan dalam penggunaan media WAN.

Berikut ini adalah protokol-protokol pengatur penggunaan media WAN:

- Point-to-Point protocol (PPP)
Protokol PPP adalah merupakan protokol standar yang paling banyak digunakan untuk membangun koneksi antara router ke router atau antara sebuah host ke dalam jaringan dalam media WAN Synchronous maupun Asynchronous.

- Serial Line Internet Protocol (SLIP)
SLIP merupakan pendahulu dari PPP yang banyak digunakan dalam membangun koneksi serial Point-to-Point yang menggunakan protokol komunikasi TCP/IP.

- High-level Data Link Control (HDLC)
Protokol layer data link ini merupakan protokol ciptaan Cisco System, jadi penggunaan protokol ini hanya ketika sebuah jalur WAN digunakan oleh dua buah perangkat router Cisco saja. Apabila perangkat selain produk Cisco yang ingin digunakan, maka protokol yang digunakan adalah PPP yang merupakan protokol standar.

- X.25/LAPB
X.25 merupakan standar buatan organisasi standardisasi ITU-T yang mendefinisikan cara koneksi antara perangkat DTE (Data Terminal Equipment) dengan DCE (Data Communication Equipment) yang memungkinkan perangkat-perangkat komputer dapat saling berkomunikasi. Kelebihan dari X.25 adalah kemampuannya untuk mendeteksi error yang sangat tinggi. Maka dari itu, protokol komunikasi ini banyak digunakan dalam media WAN analog yang tingkat error-nya tinggi.

- Frame Relay
Frame relay merupakan protokol yang khusus digunakan untuk membuat koneksi WAN jenis Packet-Switched dengan performa yang tinggi. WAN protokol ini dapat digunakan di atas berbagai macam interface jaringan. Karena untuk mendukung performanya yang hebat ini, frame relay membutuhkan media WAN yang berkecepatan tinggi, reliabel, dan bebas dari error.

- Asynchronous Transfer Mode (ATM)
ATM merupakan sebuah protokol standar internasional untuk jaringan cell relay, di mana berbagai macam servis seperti suara, video, dan data digandeng bersamaan dengan menggunakan cell-cell yang berukuran tetap. Protokol ATM banyak digunakan untuk memaksimalkan penggunaan media WAN berkecepatan sangat tinggi seperti Synchronous Optical Network (SONET).

Keuntungan WAN:

  • Penggunaan kartu kredit di seluruh dunia
  • Pengambilan uang dengan jaringan internasional (ATM Internasional)
  • Komunikasi antar kantor bisa menggunakan e-mail, chatting dan Video Conference (ViCon).
  • Pooling data dan up date data antar kantor dapat dilakukan setiap hari pada waktu yang ditentukan.
  • Data dapat dikirim melalui e-mail.
Kerugian WAN:

  • Biaya operasional mahal.
  • Susah dalam instalasi infrastrukturnya.
  • Rumit jika terjadi trouble jaringan (network trouble shooting).

Kamis, 12 April 2012

Printer Laser

Laser Printer












Terbaru dan tercepat adalah Laser Printer. Mereka menggunakan prinsip listrik statis untuk dicetak itu seperti pada mesin fotokopi. Prinsip listrik statis adalah bahwa hal itu dapat dibangun pada objek terisolasi. Malah benda atom yang bermuatan (positif dan negatif) yang tertarik satu sama lain dan melekat bersama-sama. Misalnya, potongan-potongan bahan nilon menempel di tubuh Anda, atau statis Anda dapatkan setelah menyikat rambut. Sebuah printer laser menggunakan prinsip yang sama ini untuk lem tinta di atas kertas.

  • Cara kerja Laser Printer : 

Berbeda dengan printer sebelumnya, printer laser menggunakan toner, listrik statis dan panas untuk membuat gambar di atas kertas. Toner tinta kering. Ini berisi plastik warna dan partikel. Yang toner melewati fuser di komputer dan panas yang dihasilkan itu mengikat untuk semua jenis kertas. Percetakan dengan laser printer yang cepat dan non-noda dan kualitas sangat baik karena resolusi tinggi yang dapat mencapai dengan 300 titik per inci untuk hampir 1200 dpi pada akhir yang lebih tinggi.

Komponen dasar dari sebuah printer laser adalah fuser, drum photoreceptor perakitan, pengembang roller, laser scanning unit, toner hopper, korona kawat dan lampu discharge. Sinar laser menciptakan sebuah gambar pada drum dan di mana pun itu hits, itu mengubah muatan listrik seperti positif atau negatif. Drum kemudian berguling-guling di toner. Toner diambil oleh bagian bermuatan drum dan akan ditransfer ke kertas setelah melewati fuser. Fuser memanaskan kertas untuk amalgamate tinta dan toner plastik untuk membuat gambar. Laser printer disebut “halaman printer” karena seluruh halaman ditransfer ke drum sebelum di cetak. Setiap jenis kertas dapat digunakan dalam printer ini. Laser printer dipopulerkan DTP atau Desk Top Publishing untuk itu dapat mencetak sejumlah font dan setiap grafis.

Jenis - Jenis Printer Lainnya

  • Thermal Printer













Kualitas thermal printer sama dengan dot matrix karena prinsip kerjanya    sama, hanya thermal printer menggunakan panas dan bukan tekanan atau impact. Keuntungan dari thermal printer adalah lebih. tenang (tidak berisik) dan mempunyai kecepatan tinggi yaitu 6 halaman per menit, kelemahannya adalah harus menggunakan kertas khusus.


  • Interface-











Printer dapat dihubungkan dengan komputer secara seri dengan RS-232C atau parallel dengan Centronic. Tetapi karena belum standarnya dunia teknologi komputer dan printer maka untuk menjalankan printer yang berlainan dengan jenis komputemya maka dapat digunakan perangkat lunak.



  • Plotter












Plotter merupakan salah satu peralatan output yang digunakan untuk menggambar grafik dan lain-lain. Perbedaannya dengan printer menggunakan sistem digital, yaitu analog. Contoh plotter grafik adalah ECG(Electro Cardiograph) yaitu alat yang digunakan untuk mengetahui potensial dari denyutan jantung, atau jarum seismograph untuk mencatat getaran bumi. Plotter dapat menggambar grafik pada kertas, plastik, maupun pada plastik transparan untuk digunakan dalam proyektor.

Senin, 09 April 2012

Ink Jet Printer

Ink Jet Printer









Pada pertengahan 1980-an Tinta printer diperkenalkan. Ini telah yang paling banyak digunakan dan printer populer sejauh ini. Warna pencetakan punya printer inkjet merevolusi setelah diciptakan. Seorang kepala printer Inkjet memiliki nozel kecil, yang sangat kecil tempat tetesan tinta pada kertas untuk menciptakan sebuah gambar. Titik ini sangat kecil bahkan diameter rambut manusia lebih besar. Titik-titik ini ditempatkan tepat dan dapat sampai dengan resolusi 1440 x 720 per inci. Kombinasi yang berbeda dari cartridges tinta dapat digunakan untuk printer tersebut. Tapi pada Inkjet Printer hasil cetakan lebih lama keringnya jika dibandingkan dengan Laserjet Printer.

Cara kerja sebuah printer Inkjet bekerja:

Kepala cetak printer ini secara horizontal scan halaman bolak-balik dan perakitan motor lain gulungan kertas di strip secara vertikal dan dengan demikian suatu strip dicetak pada satu waktu. Hanya setengah detik diambil untuk mencetak strip. Printer inkjet sangat populer karena kemampuan mereka untuk mencetak warna. Kebanyakan Inkjets menggunakan Teknologi Thermal. Kertas fotokopi biasa dapat digunakan pada printer ini tidak seperti kertas termal yang digunakan untuk mesin fax. Panas yang digunakan untuk api tinta ke atas kertas cetak melalui kepala. Beberapa kepala cetak dapat memiliki hingga 300 nozel. Tahan panas dan tinta berbasis air yang digunakan untuk printer tersebut.

Kamis, 05 April 2012

Dot Matrix Printer

Dot Matrix Printer










Printer jenis ini tergolong jenis printer yang mencetak ke kertas dengan cara “langsung”. Artinya, head printer langsung “mengetuk” pita tinta yang berhadapan sama kertas. Keuntungannya, cara kerja dot matrix yang mirip mesin tik ini bisa diaplikasiin juga buat pencetakan beberapa kertas sekaligus, dengan kertas karbon yang diselipkan di tiap halaman kertas.


Printer Dot-Matrix adalah pencetak yang resolusi cetaknya masih sangat rendah. Selain itu ketika sedang mencetak, printer jenis ini suaranya cenderung keras serta kualitas untuk mencetak gambar kurang baik karena gambar yang tercetak akan terlihat seperti titik-titik yang saling berhubungan.


Head dari printer jenis ini, terdiri atas 7 atau 9 ataupun 24 jarum yang tersusun secara vertical dan membentuk sebuah kolom. Pada saat bekerja, jarum yang ada akan membentuk character images melalui gesekan-gesekan jarum pada karbon dan kertas. Printer jenis ini juga merupakan character printer. Kecepatannya sangat bervariasi, tapi untuk Epson LX-80, adalah 80 caharacter per second.


Pada saat head-printer bergerak dari kiri kekanan sambil menyentuh kertas, maka huruf yang sudah terpola dalam suatu susunan jarum akan segera muncul. Pola huruf ini kemudian diterima oleh pita karbon yang dibaliknya terdapat kertas, dan terjadilah pencetakan huruf demi huruf.


Setiap character yang terbentuk akan menimbulkan suatu pola unique yang terdiri dari pelbagai titik didalam dimensi sebuah matrix. Jenis printer dot-matrix sangatlah bervariasi, ada yang berjenis color dan ada pula yang non-color. Umumnya, printer jenis dot-matrix juga hanya mempunyai satu warna, yaitu warna hitam. Untuk printer color, digunakan pita (karbon/ribon) khusus yang mempunyai 4 warna, yaitu hitam, biru, merah dan kuning.


Printer ini masih banyak digunakan karena memang terkenal ‘bandel’ (awet). Kelebihan lainnya, pita printer dot-matrix jauh lebih murah dibandingkan dengan toner (tinta) untuk printer jenis inkjet dan laserjet.

Printer

Definisi Printer

Peripheral Printer adalah alat untuk mencetak data yang dikirimkan oleh komputer. Data yang dikirimkan dapat berupa tulisan, tabel, gambar maupun foto.


Printer dapat bekerja dengan dilengkapi peralatan tambahan yaitu :

Kabel Data

Digunakan untuk menghubungkan antara printer dengan komputer. Dua jenis kabel data yang sering digunakan dalam printer yaitu : USB ( Universal Serial Bus) atau Parallel.

Power Supply

Menghubungkan printer dengan sumber listrik. Terdiri dari adaptor dan kabel penghubung ke printer.


Bagian-bagian Printer

  • Casing printer
  • Panel operator
  • Tempat kertas masuk
  • Tempat kertas keluar
  • Penutup depan 


Istilah dalam printer

Drum Bagian dari printer laser yang digunakan untuk memutar toner ke sebuah halaman. Ini kadang-kadang tersertakan bersama kartrid toner. 









Parallel port Soket tunggal di bagian belakang PC yang biasanya digunakan untuk berhubungan dengan printer atau scanner. 










Toner Tinta serupa bubuk yang digunakan dalam printer laser atau fotokopi. Sebagian besar tipe toner adalah karsinogenik.








USB Singkatan dari Universal Serial Bus. Standar koneksi yang cepat dan mudah dari periferal eksternal seperti printer dan scanner ke PC Anda.










Resolusi Jumlah detil yang terlihat pada gambar, entah itu di layar monitor atau di hasil cetak. Untuk printer dan scanner, resolusi diukur dengan satuan dot per inci (dpi) - jumlah titik tinta atau toner dalam satu inci persegi. Semakin tinggi resolusinya maka akan semakin bagus cetakan yang dihasilkan. Sebaliknya, jika resolusinya rendah maka hasil cetakan akan buruk / tidak bagus.


Rabu, 04 April 2012

SLA (SERVICE LEVEL AGREEMENT)

PERJANJIAN TINGKAT LAYANAN (SERVICE LEVEL AGREEMENT/ SLA)


Definisi

Perjanjian Tingkat Layanan (SLA) adalah bagian dari perjanjian layanan secara keseluruhan antara 2 dua entitas untuk peningkatan kinerja atau waktu pengiriman harus di perbaiki selama masa kontrak. Dua entitas tersebut biasanya dikenal sebagai penyedia layanan dan klien, dan dapat melibatkan perjanjian secara hukum karena melibatkan uang, atau kontrak lebih informal antara unit-unit bisnis internal.

SLA ini biasanya terdiri dari beberapa bagian yang mendefinisikan tanggung jawab berbagai pihak, dimana layanan tersebut bekerja dan memberikan garansi, dimana jaminan tersebut bagian dari SLA memilikitingkat harapan yang disepakati, tetapi dalam SLA mungkin terdapat tingkat ketersediaan, kemudahan layanan, kinerja, operasi atau tingkat spesifikasi untuk layanan itu sendiri. Selain itu, Perjanjian Tingkat Layanan akan menentukan target yang ideal, serta minimum yang dapat diterima.

Aplikasi Bisnis

Dengan mengetahui hal itu, diharapkan tingkat pelayanan dan juga tingkat minimum, pelanggan dapat menggunakan layanan dengan maksimal. Hal ini juga sangat membantu jika klien adalah perantara, yang menjual kembali atau bundling dengan pelayanan yang lebih besar yang sedang dijual. SLA telah digunakan sejak awal 1980-an oleh perusahaan telepon dengan pelanggan dan reseller yang lebih besar perusahaannya dengan pelayanan mereka. Konsep “tertangkap” dari bisnis unit dan usaha lainnya dalam perusahaan besar mulai menggunakan istilah dan pengaturan yang ideal dalam awal kontrak layanan telekomunikasi.

Ide menciptakan sebuah layanan yang lebih besar dari layanan yang lebih kecil hampir membutuhkan SLA dari penyedia jasa. Misalnya, untuk memiliki cakupan ponsel nasional, Anda tidak perlu untuk membangun menara dan antena di seluruh kota. Sebaliknya, Anda bisa menemukan perusahaan lokal dan daerah yang menawarkan layanan yang sama, menulis tentang SLA dan mengukur hasilnya. Untuk pelanggan anda, anda akan menawarkan SLA yang sama. Dalam SLA asli tidak memerlukan perusahaan dari mana anda membeli, dan anda dapat mengontrol biaya anda, ketika pelanggan mematuhi SLA yang anda buat dengan mereka. Hal ini memberikan kemampuan bagi Perusahaan untuk menggunakan banyak sub kontraktor untuk menyediakan pelayanan yang lebih besar, namun mengendalikan biaya dan sumber daya untuk menawarkan produk yang lebih besar.

Kekhawatiran

Dengan efisiensi datang kemungkinan korupsi. Bila menggunakan cita-cita yang ditetapkan dalam manajemen layanan TI, menerapkan metrik untuk proses dan menjamin waktu pengiriman sangat baik untuk manajemen produk manufaktur. Tetapi ketika Anda menerapkan metodologi ini ke call center, pengkodean, atau sistem desain, kehandalan dan kreativitas menghilang dan untuk kembali dalam rangka memenuhi SLA, sehingga perusahaan tidak lagi memberikan pelayanan terbaik kepada pelanggan pada akhirnya.

Rincian Teknis

Penggunaan SLA telah menyebar luas dengan penggunaan layanan manajemen TI dasar seperti SMF atau ITIL. Penggunaan umum dalam manajemen layanan TI adalah sebagai call center. Pengukuran dalam kasus-kasus ini biasanya diidentifikasi sebagai:
  1. ABA (Abandonment Average) : Sebuah persentase panggilan masuk, dimana panggilan lain di tahan, dan menjawab panggilan masuk yang lainnya
  2. ASA (Average Speed to Answer) : Rata-rata jumlah detik yang diperlukan untuk panggilan yang harus dijawab oleh pusat layanan.
  3. TSF (Time Service Factor) : Sebuah persentase panggilan dijawab dalam batas waktu tertentu, sebuah contoh yang baik adalah mengatakan 80% dalam 20 detik.
  4. FCR (First Call Resolution) : Sebuah persentase panggilan masuk yang dapat diselesaikan/ dipecahkan tanpa harus menelpon pelanggan kembali atau pelanggan tidak perlu menelpon kembali untuk menyelesaikan kasus ini.
  5. TAT (Turn Around Time) : Waktu yang dibutuhkan untuk menyelesaikan pekerjaan tertentu.

Hasil ini dicatat dan dimonitor untuk memberikan masukan kepada manajemen untuk efisiensi dan kegunaan dari personil call center dan untuk membantu mengindikasikan di mana pelatihan atau sumber daya yang lebih diperlukan.

Penggunaan SLA tidak terbatas pada dunia IT atau telekomunikasi – mereka juga digunakan untuk real estate, medis dan bidang apapun yang menyediakan produk atau layanan kepada pelanggan.Layanan berorientasi manusia dan bisnis memiliki kebutuhan untuk mengukur dan memikul tanggung jawab, dan SLA menyediakan pengukuran dan ide bagi entitas untuk menyepakati.

Minggu, 01 April 2012

Chapter 2 Modul Cisco IT Essentials: PC Hardware and Software (Version 4.1)

2.0 Introduction 
This chapter covers basic safety practices for the workplace, hardware and software tools, and the disposal of hazardous materials. Safety guidelines help protect individuals from accidents and injury and protect equipment from damage. Some of these guidelines are designed to protect the environment from contamination by discarded materials. Stay alert to situations that could result in injury or damage to equipment. Warning signs are designed to alert you to danger. Always watch for these signs and take the appropriate action according to the warning given.

After completing this chapter, you will meet these objectives:

Explain the purpose of safe working conditions and procedures.

Identify tools and software used with personal computer components and their purposes.

Implement proper tool use.

2.1 Explain the purpose of safe working conditions and procedures

Safe working conditions help to prevent injury to people and damage to computer equipment. A safe workspace is clean, organized, and properly lighted. Everyone must understand and follow safety procedures.


Follow proper procedures for handling computer equipment to reduce the risk of personal injury, damage to property, and loss of data. Any damage or loss may result in claims for damage from the owner of the property and data.



The proper disposal or recycling of hazardous computer components is a global issue. Make sure to follow regulations that govern how to dispose of specific items. Organizations that violate these regulations can be fined or face expensive legal battles.



After completing this section, you will meet these objectives:



Identify safety procedures and potential hazards for users and technicians.

Identify safety procedures to protect equipment from damage and data from loss.

Identify safety procedures to protect the environment from contamination.

2.1 Explain the purpose of safe working conditions and procedures


2.1.1 Identify safety procedures and potential hazards for users and technicians





General Safety Guidelines

Follow the basic safety guidelines to prevent cuts, burns, electrical shock, and damage to eyesight. As is best practice, make sure that a fire extinguisher and first-aid kit are available in case of fire or injury. Figure 1 shows a list of general safety guidelines.



CAUTION: Power supplies and monitors contain very high voltage. Do not wear the antistatic wrist strap when repairing power supplies or monitors.



CAUTION: Some printer parts may become very hot when in use and other parts may contain very high voltages. Make sure that the printer has had time to cool before making the repair. Check the printer manual for locations of various components that may contain high voltages. Some components may retain high voltages even after the printer is turned off.



Fire Safety Guidelines

Follow fire safety guidelines to protect lives, structures, and equipment. To avoid an electrical shock, and to prevent damage to the computer, turn off and unplug the computer before beginning a repair.



Fire can spread rapidly and be very costly. Proper use of a fire extinguisher can prevent a small fire from getting out of control. When working with computer components, always consider the possibility of an accidental fire and know how to react. If there is a fire, you should follow these safety procedures:



Never fight a fire that is out of control or not contained.

Always have a planned fire escape route before beginning any work.

Get out of the building quickly.

Contact emergency services for help.



Be sure to locate and read the instructions on the fire extinguishers in your workplace before you have to use them. Safety training may be available in your organization.



In the United States, there are four classifications for fire extinguishers. A different letter, color, and shape identifies each fire extinguisher classification, as shown in Figure 2. Each type of fire extinguisher has specific chemicals to fight different types of fires:



Class A – Paper, wood, plastics, cardboard

Class B – Gasoline, kerosene, organic solvents

Class C – Electrical equipment

Class D – Combustible metals



What types of fire extinguisher classifications are there in your country?



It is important to know how to use a fire extinguisher. Use the memory aid P-A-S-S to help you remember the basic rules of fire extinguisher operation:



P - Pull the pin.

A - Aim at the base of the fire, not at the flames.

S - Squeeze the lever.

S - Sweep the nozzle from side to side.
2.1 Explain the purpose of safe working conditions and procedures


2.1.2 Identify safety procedures to protect equipment from damage and data from loss





Electrostatic discharge (ESD), harsh climates, and poor-quality sources of electricity can cause damage to computer equipment. Follow proper handling guidelines, be aware of environmental issues, and use equipment that stabilizes power to prevent equipment damage and data loss.



ESD

Static electricity is the buildup of an electric charge resting on a surface. This buildup may zap a component and cause damage. This is known as electrostatic discharge (ESD). ESD can be destructive to the electronics in a computer system.



At least 3,000 volts of static electricity must build up before a person can feel ESD. For example, static electricity can build up on you as they walk across a carpeted floor. When you touch another person, you both receive a shock. If the discharge causes pain or makes a noise, the charge was probably above 10,000 volts. By comparison, less than 30 volts of static electricity can damage a computer component.



ESD Protection Recommendations

ESD can cause permanent damage to electrical components. Follow these recommendations to help prevent ESD damage:



Keep all components in antistatic bags until you are ready to install them.

Use grounded mats on workbenches.

Use grounded floor mats in work areas.

Use antistatic wrist straps when working on computers.



Climate

Climate affects computer equipment in a variety of ways:



If the environment temperature is too high, equipment can overheat.

If the humidity level is too low, the chance of ESD increases.

If the humidity level is too high, equipment can suffer from moisture damage.



Figure 1 shows how environmental conditions increase or decrease the risk of ESD.



Power Fluctuation Types

Voltage is the force that moves electrons through a circuit. The movement of electrons is called current. Computer circuits need voltage and current to operate electronic components. When the voltage in a computer is not accurate or steady, computer components may not operate correctly. Unsteady voltages are called power fluctuations.



The following types of AC power fluctuations can cause data loss or hardware failure:



Blackout – complete loss of AC power. A blown fuse, damaged transformer, or downed power line can cause a blackout.

Brownout – reduced voltage level of AC power that lasts for a period of time. Brownouts occur when the power line voltage drops below 80% of the normal voltage level. Overloading electrical circuits can cause a brownout.

Noise – interference from generators and lightning. Noise results in unclean power, which can cause errors in a computer system.

Spike – sudden increase in voltage that lasts for a very short period and exceeds 100% of the normal voltage on a line. Spikes can be caused by lightning strikes, but can also occur when the electrical system comes back on after a blackout.

Power surge – dramatic increase in voltage above the normal flow of electrical current. A power surge lasts for a few nanoseconds, or one-billionth of a second.



Power Protection Devices

To help shield against power fluctuation issues, use protection devices to protect the data and computer equipment:



Surge Suppressor – helps protect against damage from surges and spikes. A surge suppressor diverts extra electrical voltage on the line to the ground.

Uninterruptible Power Supply (UPS) – helps protect against potential electrical power problems by supplying electrical power to a computer or other device. The battery is constantly recharging while the UPS is in use. The UPS is able to supply a consistent quality of power when brownouts and blackouts occur. Many UPS devices are able to communicate directly with the operating system on a computer. This communication allows the UPS to safely shut down the computer and save data prior to the UPS losing all electrical power.

Standby Power Supply (SPS) – helps protect against potential electrical power problems by providing a backup battery to supply power when the incoming voltage drops below the normal level. The battery is on standby during the normal operation. When the voltage decreases, the battery provides DC power to a power inverter, which converts it to AC power for the computer. This device is not as reliable as a UPS because of the time it takes to switch over to the battery. If the switching device fails, the battery will not be able to supply power to the computer. Figure 2 shows some examples of surge suppressors, UPS, and SPS devices.



CAUTION: Never plug a printer into a UPS device. UPS manufacturers suggest not plugging a printer into a UPS for fear of overloading the UPS.
2.1 Explain the purpose of safe working conditions and procedures


2.1.3 Identify safety procedures to protect the environment from contamination





Computers and peripherals, as shown in Figure 1, contain materials that can be harmful to the environment. Hazardous materials are sometimes called toxic waste. These materials can contain high concentrations of heavy metals such as cadmium, lead, or mercury. The regulations for the disposal of hazardous materials vary according to state or country. Contact the local recycling or waste removal authorities in your community for information about disposal procedures and services.



Material Safety and Data Sheet

A Material Safety and Data Sheet (MSDS) is a fact sheet that summarizes information about material identification, including hazardous ingredients that can affect personal health, fire hazards, and first aid requirements. In Figure 2, the MSDS sheet contains chemical reactivity and incompatibility information that includes spill, leak, and disposal procedures. It also includes protective measures for the safe handling and storage of materials.



To determine if a material is classified as hazardous, consult the manufacturer's MSDS. In the U.S., the Occupational Safety and Health Administration (OSHA) requires that all hazardous materials must be accompanied by an MSDS when transferred to a new owner. The MSDS information included with products purchased for computer repairs or maintenance can be relevant to computer technicians. OSHA also requires that employees be informed about the materials that they are working with and be provided with material safety information. In the United Kingdom, Chemicals Hazard Information and Packaging for Supply Regulations 2002 (CHIP3) oversees the handling of hazardous materials. CHIP3 requires chemical suppliers to safely package and transport dangerous chemicals and to include a data sheet with the product.



NOTE: The MSDS is valuable in determining how to dispose of any potentially hazardous materials in the safest manner. Always check local regulations concerning acceptable disposal methods before disposing of any electronic equipment.



What organization governs the use of hazardous chemicals in your country? Are MSDS sheets mandatory?



The MSDS contains valuable information:



The name of the material

The physical properties of the material

Any hazardous ingredients contained in the material

Reactivity data, such as fire and explosion data

Procedures for spills or leaks

Special precautions

Health hazards

Special protection requirements



Computers and other computing devices are eventually discarded because of one of the following reasons:



Parts or components begin to fail more frequently as the device ages.

The computer becomes obsolete for the application for which it was originally intended.

Newer models have improved features.



Before discarding a computer or any of its components, it is crucial to consider safe disposal of each separate component.



Proper Disposal of Batteries

Batteries often contain rare earth metals that can be harmful to the environment. Batteries from portable computer systems may contain lead, cadmium, lithium, alkaline manganese, and mercury. These metals do not decay and will remain in the environment for many years. Mercury is commonly used in the manufacturing of batteries and is extremely toxic and harmful to humans.



Recycling batteries should be a standard practice for a technician. All batteries, including lithium-ion, nickel-cadmium, nickel-metal hydride, and lead-acid are subject to disposal procedures that comply with local environmental regulations.



Proper Disposal of Monitors or CRTs

Handle monitors and CRTs with care. Extremely high voltage can be stored in monitors and CRTs, even after being disconnected from a power source. CRTs contain glass, metal, plastics, lead, barium, and rare earth metals. According to the U.S. Environmental Protection Agency (EPA), CRTs may contain approximately 4 lbs (1.8 kg) of lead. Monitors must be disposed of in compliance with environmental regulations.



Proper Disposal of Toner Kits, Cartridges, and Developers

Used printer toner kits and printer cartridges must be disposed of properly or recycled. Some toner cartridge suppliers and manufacturers will take empty cartridges for refilling. There are also companies that specialize in refilling empty cartridges. Kits to refill inkjet printer cartridges are available but are not recommended, because the ink may leak into the printer, causing irreversible damage. This can be especially costly because using refilled inkjet cartridges may also void the inkjet printer warranty.



Proper Disposal of Chemical Solvents and Aerosol Cans

Contact the local sanitation company to learn how and where to dispose of the chemicals and solvents used to clean computers. Never dump chemicals or solvents down a sink or dispose of them in any drain that connects to public sewers.



The cans or bottles that contain solvents and other cleaning supplies must be handled carefully. Make sure that they are identified and treated as special hazardous waste. For example, some aerosol cans may explode when exposed to heat if the contents are not completely used.
2.2 Identify tools and software used with personal computer components and their purposes






For every job there is the right tool. Make sure that you are familiar with the correct use of each tool and that the right tool is used for the current task. Skilled use of tools and software makes the job less difficult and ensures that tasks are performed properly and safely.



Software tools are available that help diagnose problems. Use these tools to determine which computer device is not functioning correctly.



A technician must document all repairs and computer problems. The documentation can then be used as a reference for future problems or for other technicians who may not have encountered the problem before. The documents may be paper based, but electronic forms are preferred because they can be easily searched for specific problems.



After completing this section, you will meet these objectives:



Identify hardware tools and their purpose.

Identify software tools and their purpose.

Identify organizational tools and their purpose.

2.2 Identify tools and software used with personal computer components and their purposes


2.2.1 Identify hardware tools and their purpose





A toolkit should contain all of the tools necessary to complete hardware repairs. As you gain experience, you will learn which tools to have available for different types of jobs. Hardware tools are grouped into these four categories:



ESD tools

Hand tools

Cleaning tools

Diagnostic tools



ESD Tools

There are two ESD tools: the antistatic wrist strap and the antistatic mat. The antistatic wrist strap protects computer equipment when grounded to a computer chassis. The antistatic mat protects computer equipment by preventing static electricity from accumulating on the hardware or on the technician. Click each of the items in Figure 1 for more information on ESD tools.



Hand Tools

Most tools used in the computer assembly process are small hand tools. They are available individually or as part of a computer repair toolkit. Toolkits range widely in size, quality, and price. Click each of the items in Figure 2 for more information on hand tools.



Cleaning Tools

Having the appropriate cleaning tools is essential when maintaining or repairing computers. Using these tools ensures that computer components are not damaged during cleaning. Click each of the items in Figure 3 for more information on cleaning tools.



Diagnostic Tools

A digital multimeter and a loopback adapter are used to test hardware. Click each of the items in Figure 4 for more information on diagnostic tools.
2.2 Identify tools and software used with personal computer components and their purposes


2.2.2 Identify software tools and their purpose





A technician must be able to use a range of software tools to help diagnose problems, maintain hardware, and protect the data stored on a computer.



Disk Management Tools

You must be able to identify which software to use in different situations. Disk management tools help detect and correct disk errors, prepare a disk for data storage, and remove unwanted files.



Click each of the buttons in Figure 1 to see screen shots of the following disk management tools:



Fdisk or Disk Management – used to create and delete partitions on a hard drive

Format – used to prepare a hard drive to store information

Scandisk or Chkdsk – used to check the integrity of files and folders on a hard drive by scanning the file system. They may also check the disk surface for physical errors

Defrag – used to optimize space on a hard drive to allow faster access to programs and data

Disk Cleanup – used to clear space on a hard drive by searching for files that can be safely deleted

Disk Management – a system utility used to manage hard drives and partitions, which peforms tasks such as initializing disks, creating partitions, and formatting partitions

System File Checker (SFC) – a command-line utility that scans the operating system critical files and replaces any files that are corrupted



Use the Windows XP boot disk for troubleshooting and repairing corrupted files. The Windows XP boot disk is designed to repair Windows system files, restore damaged or lost files, and reinstall the operating system. Third-party software tools are available to assist in troubleshooting problems.



Protection Software Tools

Each year, viruses, spyware, and other types of malicious attacks infect millions of computers. These attacks can damage an operating system, application, and data. Computers that have been infected may even have problems with hardware performance or component failure.



To protect data and the integrity of the operating system and hardware, use software designed to guard against attacks and to remove malicious programs.



Various types of software are used to protect hardware and data. Click each of the buttons in Figure 2 to see screen shots of these protection software tools:



Windows XP Security Center – allows you to check the status of essential security settings on the computer. The Security Center continuously checks to make sure that the software firewall and antivirus programs are running. It also ensures that automatic updates are set to download and install automatically.

Antivirus Program – protects a computer against virus attacks.

Spyware Remover – protects against software that sends information about web surfing habits to an attacker. Spyware can be installed without the knowledge or consent of the user.

Firewall – a program that runs continuously to protect against unauthorized communications to and from your computer.

2.2 Identify tools and software used with personal computer components and their purposes


2.2.3 Identify organizational tools and their purpose





It is important that a technician document all services and repairs. These documents need to be stored centrally and made available to all other technicians. The documentation can then be used as reference material for similar problems that are encountered in the future. Good customer service includes providing the customer with a detailed description of the problem and the solution.



Personal Reference Tools

Personal Reference tools include troubleshooting guides, manufacturer manuals, quick reference guides, and a repair journal. In addition to an invoice, a technician keeps a journal of upgrades and repairs. The documentation in the journal should include descriptions of the problem, possible solutions that have been tried in order to correct the problem, and the steps taken to repair the problem. Be sure to note any configuration changes made to the equipment and any replacement parts used in the repair. This documentation will be valuable when you encounter similar situations in the future.



Notes – Make notes as you go through the investigation and repair process. Refer to these notes to avoid repeating previous steps and to determine what steps to take next.

Journal – Document the upgrades and repairs that you perform. The documentation should include descriptions of the problem, possible solutions that have been tried in order to correct the problem, and the steps taken to repair the problem. Be sure to note any configuration changes made to the equipment and any replacement parts used in the repair. Your journal, along with your notes, can be valuable when you encounter similar situations in the future.

History of repairs – Make a detailed list of problems and repairs, including the date, replacement parts, and customer information. The history allows a technician to determine what work has been performed on a computer in the past.



Internet Reference Tools

The Internet is an excellent source of information about specific hardware problems and possible solutions:



Internet search engines

News groups

Manufacturer FAQs

Online computer manuals

Online forums and chat

Technical websites



Figure 1 shows an example of a technical website.



Miscellaneous Tools

With experience, you will discover many additional items to add to the toolkit. Figure 2 shows how a roll of masking tape can be used to label parts that have been removed from a computer when a parts organizer is not available.



A working computer is also a valuable resource to take with you on computer repairs in the field. A working computer can be used to research information, download tools or drivers, or communicate with other technicians.



Figure 3 shows the types of computer replacement parts to include in a toolkit. Make sure that the parts are in good working order before you use them. Using known good working components to replace possible bad ones in computers will help you quickly determine which component may not be working properly.
2.3 Implement proper tool use






Safety in the workplace is everyone's responsibility. You are much less likely to injure yourself or damage components when using the proper tool for the job.



Before cleaning or repairing equipment, check to make sure that your tools are in good condition. Clean, repair, or replace any items that are not functioning adequately.



After completing this section, you will meet these objectives:



Demonstrate proper use of an antistatic wrist strap.

Demonstrate proper use of an antistatic mat.

Demonstrate proper use of various hand tools.

Demonstrate proper use of cleaning materials.

2.3 Implement proper tool use


2.3.1 Demonstrate proper use of an antistatic wrist strap





As discussed previously, an example of ESD is the small shock that someone receives when you walk across a room with carpet and touch a doorknob. Although the small shock is harmless to you, the same electrical charge passing from you to a computer can damage its components. Wearing an antistatic wrist strap can prevent ESD damage to computer components.



The purpose of an antistatic wrist strap is to equalize the electrical charge between you and the equipment. The antistatic wrist strap is a conductor that connects your body to the equipment that you are working on. When static electricity builds up in your body, the connection made by the wrist strap to the equipment, or ground, channels the electricity through the wire that connects the strap.



As shown in Figure 1, the wrist strap has two parts and is easy to wear:



Wrap the strap around your wrist and secure it using the snap or Velcro. The metal on the back of the wrist strap must remain in contact with the skin at all times.

Snap the connector on the end of the wire to the wrist strap and connect the other end either to the equipment or to the same grounding point that the antistatic mat is connected to. The metal skeleton of the case is a good place to connect the wire. When connecting the wire to equipment you are working on, choose an unpainted metal surface. A painted surface does not conduct the electricity as well as unpainted metal.



NOTE: Attach the wire on the same side of the equipment as the arm wearing the antistatic wrist strap. This will help to keep the wire out of the way while you are working.



Although wearing a wrist strap will help to prevent ESD, you can further reduce the risks by not wearing clothing made of silk, polyester, or wool. These fabrics are more likely to generate a static charge.



NOTE: Technicians should roll up their sleeves, remove scarfs or ties, and tuck in their shirts to prevent interference from clothing. Ensure that earrings, necklaces, and other loose jewelry are properly secured.



CAUTION: Never wear an antistatic wrist strap if you are repairing a monitor or CRT.
2.3 Implement proper tool use


2.3.2 Demonstrate proper use of an antistatic mat





You may not always have the option to work on a computer in a properly equipped workspace. If you can control the environment, try to set up your workspace away from carpeted areas. Carpets can cause the buildup of electrostatic charges. If you cannot avoid the carpeting, ground yourself to the unpainted portion of the case of the computer on which you are working before touching any components.



Antistatic Mat

An antistatic mat is slightly conductive. It works by drawing static electricity away from a component and transferring it safely from equipment to a grounding point, as shown in Figure 1:



Lay the mat on the workspace next to or under the computer case.

Clip the mat to the case to provide a grounded surface on which you can place parts as you remove them from the system.



Reducing the potential for ESD reduces the likelihood of damage to delicate circuits or components.



NOTE: Always handle components by the edges.



Workbench

When you are working at a workbench, ground the workbench and the antistatic floor mat. By standing on the mat and wearing the wrist strap, your body has the same charge as the equipment and reduces the probability of ESD.
2.3 Implement proper tool use


2.3.3 Demonstrate proper use of various hand tools





A technician needs to be able to properly use each tool in the toolkit. This topic covers many of the various hand tools used when repairing computers.



Screws

Match each screw with the proper screwdriver. Place the tip of the screwdriver on the head of the screw. Turn the screwdriver clockwise to tighten the screw and counterclockwise to loosen the screw, as shown in Figure 1.



Screws can become stripped if you over-tighten them with a screwdriver. A stripped screw, shown in Figure 2, may get stuck in the screw hole, or it may not tighten firmly. Discard stripped screws.



Flat Head Screwdriver

As shown in Figure 3, use a flat head screwdriver when you are working with a slotted screw. Do not use a flat head screwdriver to remove a Phillips head screw. Never use a screwdriver as a pry bar. If you can not remove a component, check to see if there is a clip or latch that is securing the component in place.



CAUTION: If excessive force is needed to remove or add a component, something is probably wrong. Take a second look to make sure that you have not missed a screw or a locking clip that is holding the component in place. Refer to the device manual or diagram for additional information.



Phillips Head Screwdriver

As shown in Figure 4, use a Phillips head screwdriver with crosshead screws. Do not use this type of screwdriver to puncture anything. This will damage the head of the screwdriver.



Hex Driver

As shown in Figure 5, use a hex driver to loosen and tighten bolts that have a hexagonal (six-sided) head. Hex bolts should not be over-tightened because the threads of the bolts can be stripped. Do not use a hex driver that is too large for the bolt that you are using.



CAUTION: Some tools are magnetized. When working around electronic devices, be sure that the tools you are using have not been magnetized. Magnetic fields can be harmful to data stored on magnetic media. Test your tool by touching the tool with a screw. If the screw is attracted to the tool, do not use the tool.



Part Retriever, Needle-Nose Pliers, or Tweezers

As shown in Figure 6, the part retriever, needle-nose pliers, and tweezers can be used to place and retrieve parts that may be hard to reach with your fingers. Do not scratch or hit any components when using these tools.



CAUTION: Pencils should not be used inside the computer to change the setting of switches or to pry off jumpers. The pencil lead can act as a conductor and may damage the computer components.
2.3 Implement proper tool use


2.3.4 Demonstrate proper use of cleaning materials





Keeping computers clean inside and out is a vital part of a maintenance program. Dirt can cause problems with the physical operation of fans, buttons, and other mechanical components. Figure 1 shows severe dust buildup on computer components. On electrical components, an excessive buildup of dust will act like an insulator and trap the heat. This insulation will impair the ability of heat sinks and cooling fans to keep components cool, causing chips and circuits to overheat and fail.



CAUTION: Before cleaning any device, turn it off and unplug the device from the power source.



Computer Cases and Monitors

Clean computer cases and the outside of monitors with a mild cleaning solution on a damp, lint-free cloth. Mix one drop of dishwashing liquid with four ounces of water to create the cleaning solution. If any water drips inside the case, allow enough time for the liquid to dry before powering on the computer.



LCD Screens

Do not use ammoniated glass cleaners or any other solution on an LCD screen unless the cleaner is specifically designed for the purpose. Harsh chemicals will damage the coating on the screen. There is no glass protecting these screens, so be gentle when cleaning them and do not press firmly on the screen.



CRT Screens

To clean the screens of CRT monitors, dampen a soft, clean, lint-free cloth with distilled water and wipe the screen from top to bottom. Then use a soft, dry cloth to wipe the screen and remove any streaking after you have cleaned the monitor.



Clean dusty components with a can of compressed air. Compressed air does not cause electrostatic buildup on components. Make sure that you are in a well-ventilated area before blowing the dust out of the computer. A best practice is to wear a dust mask to make sure that you do not breathe in the dust particles.



Blow out the dust using short bursts from the can. Never tip the can or use the compressed air can upside down. Do not allow the fan blades to spin from the force of the compressed air. Hold the fan in place. Fan motors can be ruined from spinning when the motor is not turned on.



Component Contacts

Clean the contacts on components with isopropyl alcohol. Do not use rubbing alcohol. Rubbing alcohol contains impurities that can damage contacts. Make sure that the contacts do not collect any lint from the cloth or cotton swab. Blow any lint off the contacts with compressed air before reinstallation.



Keyboard

Clean a desktop keyboard with compressed air or a small, hand-held vacuum cleaner with a brush attachment.



CAUTION: Never use a standard vacuum cleaner inside a computer case. The plastic parts of the vacuum cleaner can build up static electricity and discharge to the components. Use only a vacuum approved for electronic components.



Mouse

Use glass cleaner and a soft cloth to clean the outside of the mouse. Do not spray glass cleaner directly on the mouse. If cleaning a ball mouse, you can remove the ball and clean it with glass cleaner and a soft cloth. Wipe the rollers clean inside the mouse with the same cloth. You may need to use a nail file to clean the rollers on the mouse. Do not spray any liquids inside the mouse.



The chart in Figure 2 indicates the computer items that you should clean and the cleaning materials you should use in each case.
2.4 Summary






This chapter discussed safe lab procedures, correct tool usage, and the proper disposal of computer components and supplies. You have familiarized yourself in the lab with many of the tools used to build, service, and clean computer and electronic components. You have also learned the importance of organizational tools and how these tools help you work more efficiently.



The following are some of the important concepts to remember from this chapter:



Work in a safe manner to protect both users and equipment.

Follow all safety guidelines to prevent injuries to yourself and to others.

Know how to protect equipment from ESD damage.

Know about and be able to prevent power issues that can cause equipment damage or data loss.

Know which products and supplies require special disposal procedures.

Familiarize yourself with MSDS sheets for both safety issues and disposal restrictions to help protect the environment.

Be able to use the correct tools for the task.

Know how to clean components safely.

Use organizational tools during computer repairs.