3 February 2017

5 Computers That Change The World Of PC(s)



Personal Computer (PC)


A personal computer is a general-purpose computer whose size, capabilities and original sale price make it useful for individuals, and is intended to be operated directly by an end-user with no intervening computer operator. This contrasts with the batch processing or time-sharing models that allowed larger, more expensive minicomputer and mainframe systems to be used by many people, usually at the same time. A related term is "PC" that was initially an acronym for "personal computer".

1971 - Kenbak-1


Kenbak

The Kenbak-1 is considered by the Computer History Museum and the American Computer Museum to be the world's first "personal computer". Only 40 machines were ever built and sold. It was designed and invented by John Blankenbaker of Kenbak Corporation in 1970, and was first sold in early 1971. The system first sold for US$750. Only around 10 machines are now known to exist worldwide, with various collectors. In 1973, production of the Kenbak-1 stopped as Kenbak Corporation folded.

Since the Kenbak-1 was invented before the first microprocessor, the machine didn't have a one-chip CPU but instead was based purely on discrete TTL chips. The 8-bit machine offered 256 bytes of memory (=1/4096 megabyte). The instruction cycle time was 1 microsecond (equivalent to an instruction clock speed of 1 MHz), but actual execution speed averaged below 1000 instructions per second due to architectural constraints such as slow access to serial memory.

1975 - MITS Altair 8800



The MITS Altair 8800 is a microcomputer designed in 1974 based on the Intel 8080 CPU. Interest grew quickly after it was featured on the cover of the January 1975 issue (published in December 1974) of Popular Electronics, and was sold by mail order through advertisements there, in Radio-Electronics, and in other hobbyist magazines. The designers hoped to sell a few hundred build-it-yourself kits to hobbyists, and were surprised when they sold thousands in the first month. 

The Altair also appealed to individuals and businesses that just wanted a computer and purchased the assembled version. The Altair is widely recognized as the spark that ignited the microcomputer revolution. The computer bus designed for the Altair was to become a de facto standard in the form of the S-100 bus, and the first programming language for the machine was Microsoft's founding product, Altair BASIC. Additional Altair cards available from MITS:



1975 - IBM 5100


IBM 5100

The IBM 5100 Portable Computer was a portable computer introduced in September 1975, six years before the IBM PC. It was the evolution of a prototype called the SCAMP (Special Computer APL Machine Portable) that was developed at the IBM Palo Alto Scientific Center in 1973. In January 1978 IBM announced the IBM 5110, its larger cousin, and in February 1980 IBM announced the IBM 5120. The 5100 was withdrawn in March 1982.

1976 - Apple I


Apple I

The original Apple Computer, also known retroactively as the Apple I, or Apple-1, was released by the Apple Computer Company (now Apple Inc.) in 1976. They were designed and hand-built by Steve Wozniak. Wozniak's friend Steve Jobs had the idea of selling the computer. The Apple I was Apple's first product, and to finance its creation, Jobs sold his only means of transportation, a VW Microbus, and Wozniak sold his HP-65 calculator for $500. It was demonstrated in July 1976 at the Homebrew Computer Club in Palo Alto, California.


  • Release date April 11, 1976
  • Introductory price $ 666.66
  • Discontinued September 30, 1977
  • CPU MOS 6502 @ 1 MHz
  • Memory 4 KB standard
  • Expandable to 8 KB or 48 KB using expansion cards
  • Graphics 40x24 characters, hardware-implemented scrolling

Successor Apple II


Apple II
The Apple II, or Apple ][, became one of the most popular computers ever. Although it is a vast improvement over the Apple I, it contains the same processor and runs at the same speed. 

New features include a color display, eight internal expansion slots, and a case with a keyboard. That may sound funny, but the Apple I and many other early computers didn't necessarily have a case or even a keyboard. On some systems you had to added your own keyboard, if possible, and on others you toggled switches to enter programs and issue commands.


Thanks for reading...


REFERENCE
[1]www.computerhistory.org
[2]www.oldcomputers.net
[3]www.sellcell.com
[4]www.apple-history.com

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