RADIO COPORATION OF AMERICA(RCA)

U.S. RADIO COMPANY
In 1919, General Electric (GE) formed a privately owned corporation to acquire the assets of the wireless radio company American Marconi from British Marconi. The organization, known as the Radio Corporation of America or RCA, was formally incorporated on 17 October of that year. Shortly thereafter, American Telephone and Telegraph (AT and T) and Westinghouse acquired RCA assets and became joint owners of RCA. In 1926, RCA formed a new company, the National Broadcasting Company (NBC), to oversee operation of radio stations owned by RCA, General Electric, Westinghouse and AT and T.
In the early 1930's, the Justice Department filed an antitrust suit against the company. In a 1932 consent decree, the organization's operations were separated and GE, AT and T, and Westinghouse were forced to sell their interests in the company. RCA retained its patents and full ownership of NBC. Shortly after becoming an independent company, RCA moved into new headquarters in the Rockefeller Center complex in New York City, into what later became known as Radio City.
While other American companies were cutting back on research expenditures during the depression years, David Sarnoff, President of RCA since 1930, was a staunch advocate of technological innovation. He expanded RCA's technology research division, devoting increased resources to television technology. Television pioneer Vladimir Zworykin was placed in charge of RCA's television research division. RCA acquired competing and secondary patents related to television technology, and once the organization felt that the technology had attained an appropriate level of refinement, it pushed for commercialization of the new medium.
In 1938, RCA persuaded the Radio Manufacturers Association (RMA) to consider adoption of its television system for standardization. The RMA adopted the RCA version, a 441 line, 30 pictures per second system, and presented the new standard to the FCC on 10 September 1938. Upon the recommendation of the RMA, the Federal Communications Commission (FCC) scheduled formal hearings to address the adoption of standards. The hearings, however, did not take place until January 1940.
In the interim, RCA began production of receivers and initiated a limited schedule of television programming from the New York transmitters of the National Broadcasting Corporation (NBC) basing their service upon the RMA-RCA standards. The service was inaugurated in conjunction with the opening of the New York World's Fair on 30 April 1939 and continued throughout the year. At the commission's hearing addressing standards on 15 January 1940, opposition to the proposed RMA standards emerged. The two strongest opponents of the standard were DuMont Laboratories and Philco Radio and Television. One of the criticisms voiced by both organizations was the assertion that the 441 line standard did not provide sufficient visual detail and definition. Given the lack of a clear industry consensus, the Commission did not act on the proposed RMA standards. Despite the absence of official approval, RCA continued to employ the RMA standards and announced plans in early 1940 to increase production of television receivers, cut the price to consumers by one-third, and double their programming schedule. While some commentators saw this as a reasonable and progressive action, the Commission perceived it as a step towards prematurely freezing the standards in place, and as a consequence, scheduled another set of public hearings for 8 April 1940. At these hearings, opponents argued that the action taken by RCA was stifling research and development into other alternative standards. As a result of the hearings, the Commission eliminated commercial broadcasting until further development and refinement had transpired. Furthermore, the Commission asserted that commercialization of broadcasting would not be permitted until there was industry consensus and agreement on one common system. To marshal industry wide support for a single standard, the RMA formed the National Television System Committee (NTSC). The NTSC standards, a 525 line, 60 fields per second system, were approved by the FCC in 1941.
Several years later, RCA also became a major participant in the establishment of color television standards. In 1949, the organization proposed to the FCC that its dot sequential color system, which was compatible with existing black and white receivers, be adopted as the new color standard. Citing shortcomings in the compatible systems offered by RCA and other organizations, the FCC opted to formally adopt an incompatible color system offered by the Columbia Broadcasting System as the color standard. RCA appealed this decision all the way to the Supreme Court, while simultaneously refining their color system. A second NTSC was formed to examine the color issue. In 1953, the FCC reversed itself and endorsed a modified version of the RCA dot sequential system compatible color system offered by the NTSC.
In the 1950s, RCA continued the military and defense work in which it had been heavily engaged during World War II. In the late 1950s and early 1960s, the company became involved with both satellite technology and the space program. During the 1960s, RCA began to diversify as the company acquired such disparate entities as the publishing firm Random House, and the car rental company Hertz. Throughout the 1970s and early 1980s, RCA began to divest itself of many of its acquired subsidiaries. In June 1986, RCA was acquired by General Electric, the organization that had originally established it as a subsidiary. GE retained the brand name RCA, established NBC as a relatively autonomous unit, and combined the remainder of RCA's businesses with GE operations.

Data segerak & Data tak segerak.....

DATA TAK SEGERAK
· Elak masalah timing dgn tidak menghantar arus bit berterusan tanpa henti
· Data dihantar sebanyak 1 character setiap masa. 1 character = 5-8 bit
· Pemasaan atau kesegerakkan (synchronization) perlu dikelakan dalam 1 character
tersebut sahaja
· Penerima boleh mensegerak (synchronize) pada permulaan setiap character.
· Tiada character dipancarkan à talian antara penghantar dan penerima berada dalam
keadaan idle.
· Permulaan character ditandakan dengan bit mula (start bit) binari 0, diikuti dengan 5-8
bit yang mewakili data character.
· Bit character dihantar dgn LSB sebagai data pertama
· Bit pariti akan mengekori MSB terakhir. Bit pariti terdiri daripada pariti ganjil atau pariti
genap à kegunaannya utk mengesan ralat
· Elemen terakhir à stop (binari 1)
· Tempoh minimum `stop` ditetapkan sebagai 1, 1.5 atau 2 kali ganda tempoh 1 bit biasa
· Stop = idle à penghantar terus menghantar bit stop selagi tiada data baru utk dihantar
· Keperluan timing bagi sistem tak segerak adalah mudah
· Proses penyegerakan dalam penghantaran tak segerak terbahagi kepada tiga kaedah:

• Penyegerakan bit iaitu dicapai dengan menggunakan 1 klok penerima berfrekuensi 16/32/64 X frekuensi data yang terdapat di penghantar.
  
• Penyegerakan aksara iaitu yang dicapai dengan menggunakan bit kawalan mula dan akhir untuk setiap aksara.
  
• Penyegerakan frame / rangka iaitu dicapai dengan menggunakan aksara kawalan STX untuk tanda permulaan frame dan ETX untuk tanda tamat frame.
  

DATA SEGERAK

• Penghantaran berterusan tanpa bit start dan stop
  Saiz blok data boleh mengandungi banyak bit
  Utk mengelakkan perbezaan timing (timing drift) antara penghantar dan penerima, perlu penyegerakkan jam (clock synchronization)
  Contoh penyegerakkan:
  1. Salah satu (penerima / pemancar) menghantar maklumat jam melalui talian khas yang berasingan dari talian maklumat
  Cth maklumat jam: denyutan pendek pada setiap masa bit
  Masalah: berguna utk jarak dekat
  Jarak jauh à talian alami hingar, maklumat jam boleh jadi tidak tepat
  2. Masukkan maklumat jam pada data yang dihantar
  à boleh dilakukan pada kod Manchester, dsb
  3. Masukan maklumat jam pada frekuensi gelombang.
  cth: pada fasa gelombang pembawa
  Frame penghantaran segerak
  Penghantaran segerak memerlukan tahap kesegerakkan yang berbeza supaya penerima mengetahui tentang mula dan berakhirnya suatu blok data
  Blok data dimulakan dgn turutan bit preamble, diakhiri dgn turutan bit postamble
  Maklumat kawalan à digunakan dalam kawalan aliran data
  Frame: data + preamble + postamble + maklumat kawalan
  Frame mula dgn preamble dipanggil flag (8 bit)
  Flag sama digunakan pada postamble
  Penerima mencari kehadiran flag utk menandakan permulaan frame, diikuti dgn maklumat kawalan, blok data (saiz tidak tetap), maklumat kawalan dan akhirnya flag diulangi
  Penghantaran segerak lebih efisyen utk data besar
  Tak segerak perlu 20% atau lebih overhead
  Maklumat kawalan + preamble + postamble biasanya < 100 bit
  Terdapat dua kaedah untuk melakukan penyegerakkan suatu sambungan data iaitu:
  a. Penyegerakkan berasaskan aksara
  Bagi kaedah ini setiap kerangka yang akan dihantar terdiri dari aksara-aksara 7 atau 8 bit, yang akan dihantar tanpa sebarang lengahan di anatara setiap bit. Penerima, setelah mendapat penyegerakkan klok(bit), mesti boleh mengesan mula dan akhir setiap aksara-penyegerakkan aksara dan mengesan mula dan akhir setiap kerangka-penyegerakkan kerangka.
  b. Penyegerakkan berasaskan bit
  Bagi kaedah ini setiap kerangka yang dihantar boleh mengandungi bilangan bit-bit yang tidak tetap, tidak semestinya rangkaian 8 bit. Bila kandungan kerangka dihantar ke talian penghantaran akan mengesan bila ada turutan 5 digit-digit binary æ1Æ dan memasukkan binary æ0Æ secara otomatik. Dengan cara ini aturan flag 01111110 tidak akan hadir di antara flag mula dan flag akhir.
  

Topologi pokok....Topologi mesh....

Topologi pokok: Topologi pokok atau topologi berheiraki mengandungi beberapa lapisan yang mana nod-nod di paras yang lebih rendah disambung kepada satu nod diparas sebelah atas . Dalam topologi ini , nod-nod boleh diberikan tugas-tugas khas . Nod-nod ini kemudiannya disambungkan ke heiraki rangkaian untuk melakukan tugas-tugas bersepadu . Topologi ini dijumpai dalam penyambungan sesama rangkaian-rangkaian bas . Kelemahan kos pendawaiannya tinggi , pengendalian data lebih kompleks dan masa yang diperlukan bagi menghantar data lebih lambat.
Topologi mesh: Topologi mesh ialah satu cara di mana data, bunyi dan kaedah dihalakan antara nod rangkaian. Ia membolehkan sambungan dan konfigurasi kerosakan atau sekatan laluan diteruskan semula dengan loncatan dari nod ke nod sehingga tiba ke destinasi. Satu rangkaian mesh mempunyai beberapa nod di mana semuanya tersambung satu sama lain adalah sebuah sambungan rangkaian lengkap. Rangkaian mesh berbeza dari rangkaian lain dalam setiap bahagian komponennya yang membolehkan setiap sambungan ke sambungan lain melalui loncatan dan ia biasanya tidak bergerak. Rangkaian mesh boleh juga dilihat sebagai sejenis rangkaian ad hoc. Rangkaian ad hoc bergerak (mobile ad-hoc network atau MANET) dan rangkaian mesh oleh itu mempunyai hubungan rapat, tetapi MANET selalunya membahagi setiap masalah yang dikenal pasti dengan pergerakan setiap nod.

B2B.....C2C.....B2C....~

B2B..... mAkSuDnYa....:bUsiNEsS-To-bUsInESs...*
- PeRnIaGaAn kE PErNiAgaAn....
-TrAnsAkSi E-DaGaNg pLg bEsAr....
-mBeKaLkAn pErKhDmTaN Ke PrNiAgAaN LaIn sPrTi :
.....P'IkLaNan, PnYeLiDiKaN, kRdIt & lAiN2....

B2C...mAkSuNyA....:BuSiNeSs-To- CoNsUmEr....*
-dRi pNiAgAaN Ke pLNgGaN....
-pNiAgA MyDiAkAn "kDaI eLeKtrRoNiK"

C2C...mKsDnYa....:coNsUmEr-To-cNsUmEr....*
-DrI pLNgGaN kE PLnGgAn....
-pLnGgAn mJuAl bRaNg kE PlNgGan lAiN SeCaRa tRuS...

windows

window adalah sebuah sistem pengendalian yang dibangunkan dan dipasarkan oleh microsoft sehingga kini dan terdapat pelbagai versi windows antaranya windows 95, windows 98,windows ME,window NT,window XP danyang terbaru windows vista yang dilancarkan pada tahun 2007.

MC OS yang bererti macintosh operating system atau sistem operasi macintosh, adalah sistem operasi untuk komputer Apple macintosh.MC OS merupakan sistem operasi pertama yang mengunakan antara muka pengguna grafik(GUI).pasukan macintosh termasuk Bill Atkinson,Jef Raskin dan Andy Hertzfeld.

Myeg servis dan Rilek portal

Myeg servis berhad merupakan sebuah syarikat pemegang konsensi kerajaan elektronik malaysia di bawah aplikasi perdana MSC.Berperanan sebagai pembekal aplikasi e- khidmat yang menghubungkan pihak kerajaan, rakyat dan syarikat perkhidmatan.


Portal rilek ialah rangkaian interaktif laman elektronik kerajaan
eServices with RILEKeServices is one of the six Malaysia’s Electronic Government Flagship Applications. In conjunction with the said initiative, KOMMS introduces RILEK to provide innovative online solutions and direct system linkages to JPJ, TNB, Telekom and various financial institutions. These provide us an edge in online payment authorization and multiple services integration.RILEK provides different options for you, either through our user-friendly kiosks located widely, our website at www.rilek.com.my or RILEK Center, within one host; serving the same purpose.

aktiviti kls mgu lps.....

mgu lps dlm kls ktorng belajr bab sejarah perkmbngn teknologi