A computer is a general-purpose device that can be programmed to carry out a set of arithmetic or logical operations automatically. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem.
Conventionally, a computer consists of at least one processing element, typically a central processing unit (CPU), and some form of memory. The processing element carries out arithmetic and logic operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices allow information to be retrieved from an external source, and the result of operations saved and retrieved.
Mechanical analog computers started appearing in the first century and were later used in the medieval era for astronomical calculations. In World War II, mechanical analog computers were used for specialized military applications such as calculating torpedo aiming. During this time the first electronic digital computers were developed. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).
Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.Computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries. Personal computers in their various forms are icons of the Information Age and are generally considered as “computers”. However, the embedded computers found in many devices from MP3 players to fighter aircraft and from electronic toys to industrial robots are the most numerous.
The Macintosh 128K
The Macintosh 128K, originally released as the Apple Macintosh, is the original Apple Macintosh personal computer. Its beige case consisted of a 9 in (23 cm) CRT monitor and came with a keyboard and mouse. A handle built into the top of the case made it easier for the computer to be lifted and carried. It had an initial selling price of $2,495 (equivalent to $5,683 in 2015). The Macintosh was introduced by the now-famous $370,000 (equivalent to $842,751 in 2015) television commercial by Ridley Scott, “1984,” that most notably aired on CBS during the third quarter of Super Bowl XVIII on January 22, 1984.Sales of the Macintosh were strong from its initial release on January 24, 1984, and reached 70,000 units on May 3, 1984.Upon the release of its successor, the Macintosh 512K, it was rebranded as the Macintosh 128K.
The original model range was the UNIVAC I (UNIVersal Automatic Computer I), the second commercial computer made in the United States.The main memory consisted of tanks of liquid mercury implementing delay line memory, arranged in 1000 words of 12 alphanumeric characters each. The first machine was delivered on 31 March 1951.
The UNIVAC II was an improvement to the UNIVAC I that UNIVAC first delivered in 1958. The improvements included magnetic (non-mercury) core memory of 2000 to 10000 words, UNISERVO II tape drives which could use either the old UNIVAC I metal tapes or the new PET film tapes, and some circuits that were transistorized (although it was still a vacuum tube computer). It was fully compatible with existing UNIVAC I programs for both code and data. The UNIVAC II also added some instructions to the UNIVAC I’s instruction set.
Sperry Rand began shipment of UNIVAC III in 1962, and produced 96 UNIVAC III systems. Unlike the UNIVAC I and UNIVAC II, however, it was a binary machine as well as maintaining support for all UNIVAC I and UNIVAC II decimal and alphanumeric data formats for backward compatibility. This was the last of the original UNIVAC machines.
The UNIVAC Solid State was a 2-address, decimal computer, with memory on a rotating drum with 5000 signed 10 digit words, aimed at the general purpose business market. It came in two versions: the Solid State 80 (IBM-Hollerith 80 column cards) and the Solid State 90 (Remington-Rand 90 column cards). This computer used magnetic amplifiers, not transistors, because the transistors then available had highly variable characteristics and were not sufficiently reliable. The magnetic amplifiers were based on tiny magnetic cores with two wire windings. The magnetic amplifiers required powerful pulses of heavy current produced by a transmitter-type vacuum-tube, of a type still used in amateur radio final amplifiers. Thus the Solid State depended, at the heart of its operations, on a vacuum tube.
ZX Spectrum 16K/48K
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd.
Referred to during development as the ZX81 Colour and ZX82,the machine was launched as the ZX Spectrum by Sinclair to highlight the machine’s colour display, compared with the black and white of its predecessor, the ZX81.The Spectrum was ultimately released as eight different models, ranging from the entry level model with 16 KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987; together they sold in excess of 5 million units worldwide (not counting numerous clones).
The Spectrum was among the first mainstream-audience home computers in the UK, similar in significance to the Commodore 64 in the USA. The introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine,the effects of which are still seen;some credit it as the machine which launched the UK IT industry.Licensing deals and clones followed, and earned Clive Sinclair a knighthood for “services to British industry”.
The Commodore 64, Oric-1 and Atmos, BBC Microcomputer and later the Amstrad CPC range were rivals to the Spectrum in the UK market during the early 1980s. Over 24,000 software titles have been released since the Spectrum’s launch and new titles continue to be released–over 100 in 2012.In 2014, a bluetooth keyboard modelled on the Spectrum was announced.
The Commodore 64, also known as the C64, C-64, C= 64,[n 1] or occasionally CBM 64 or VIC-64,is an 8-bit home computer introduced in January 1982 by Commodore International. It is listed in the Guinness World Records as the highest-selling single computer model of all time,with independent estimates placing the number sold between 10 and 17 million units.
Volume production started in early 1982, with machines being released on to the market in August at a price of US$595 (roughly equivalent to $1,500 in 2015).Preceded by the Commodore VIC-20 and Commodore PET, the C64 takes its name from its 64 kilobytes (65,536 bytes) of RAM, and has technologically superior sound and graphical specifications when compared to some earlier systems such as the Apple II and Atari 800, with multi-color sprites and a more advanced sound processor.
The C64 dominated the low-end computer market for most of the 1980s.For a substantial period (1983–1986), the C64 had between 30% and 40% share of the US market and two million units sold per year,outselling the IBM PC compatibles, Apple Inc. computers, and the Atari 8-bit family of computers. Sam Tramiel, a later Atari president and the son of Commodore’s founder, said in a 1989 interview, “When I was at Commodore we were building 400,000 C64s a month for a couple of years.”In the UK market, the 64 faced competition from the BBC Micro and the ZX Spectrum but the 64 was still one of the two most-popular computers in the UK.
Dell Optiplex GS Pentium II 400 Mhz
OptiPlex is a line of desktop computers from Dell aimed at the corporate, government and education markets. The systems typically contain Intel CPUs, beginning with the Pentium and currently with the Core i7 (as of mid-2014) although Dell sells some models with AMD CPUs as well. Business-oriented components, such as Gigabit Ethernet and software such as data protection utilities, often come standard with the Optiplex.
The newest OptiPlex models break from Dell’s proprietary form factors and follow, for the most part, the ATX standard, usually to the Mini-ITX form factor for SFF computers, and MicroATX form factor for DT and MT computers.
The OptiPlex series comes in various sizes which have evolved as the style of chassis has changed.
The Macintosh Portable was Apple Inc.’s first battery-powered portable Macintosh personal computer. Released on September 20, 1989, it was received with excitement from most critics but consumer sales were quite low. It featured a fast, sharp, and expensive black and white active matrix LCD screen in a hinged design that covered the keyboard when the machine was not in use. The Portable was one of the early consumer laptops to employ an active matrix panel, and only the most expensive of the initial Powerbook line, the Powerbook 170, used one, due to the high cost. The cursor pointing function was handled by a built-in trackball that could be removed and located on either side of the keyboard. It used expensive SRAM in an effort to maximize battery life and to provide an “instant on” low power sleep mode. The machine was designed to be high-performance, at the cost of price and weight.
Alienware is an American computer hardware subsidiary of Dell, Inc. Their products are designed for gaming and can be identified by their science-fiction-themed designs.Alienware was founded in 1996 by Nelson Gonzalez and Alex Aguila. The company’s corporate headquarters is located in The Hammocks, in Miami, Florida.
Dell had considered buying Alienware since 2002, but did not agree to purchase the company until March 22, 2006.The new subsidiary retains control of its design and marketing while benefiting from Dell’s purchasing power, economies of scale, and supply chain, which lower its operating costs.
Initially, Dell maintained its competing XPS line of gaming PCs, often selling computers with similar specifications, which may have hurt Alienware’s market share within its market segment.Due to corporate restructuring in the spring of 2008, the XPS brand was scaled down, and the Desktop line was eliminated leaving only the XPS Notebooks.Product development of gaming PCs was consolidated with Dell’s gaming division, with Alienware becoming Dell’s premier gaming brand.On June 2, 2009, The M17x was introduced as the first Alienware/Dell branded system. Alienware now represents the non premium performance space in Dell’s consumer family of products.This launch also expanded Alienware’s global reach from 6 to 35 countries while supporting 17 different languages.
MacBook Pro Retina
The third generation MacBook Pro received positive reviews of the Retina display, flash storage, and power. It was criticized, however, for its high price and lack of an Ethernet port and optical drive. Roman Loyola of Macworld said that the Retina MacBook Pro was “groundbreaking” and made people “rethink how they use technology.” He praised the inclusion of USB 3.0 and the slimmer body.Dan Ackerman of CNET commented “I’ve previously called the 15-inch MacBook Pro one of the most universally useful all-around laptops you can buy. This new version adds to that with HDMI, faster ports, and more portability. But it also subtracts from that with its exclusion of an optical drive and Ethernet port, plus its very high starting price. The Pro and Retina Pro are clearly two laptops designed for two different users, and with the exception of all-day commuters who need something closer to a MacBook Air or ultrabook, one of the two branches of the MacBook Pro family tree is still probably the most universally useful laptop you can buy.”
The Retina MacBook line has no internal optical drives. External drives such as Apple’s SuperDrive (pictured) must be used instead.
Joel Santo Domingo of PC Magazine gave the MacBook Pro an “Editor’s Choice” rating. He praised “brilliant Retina display” the thin design, port selection and speedy storage, and highlighted the expandability via Thunderbolt ports which support up to seven devices each.David Pogue of The New York Times praised the 15-inch model’s screen, keyboard, sound, start-up time, cosmetics, battery life, storage, and RAM capacity. They criticized the lack of a SuperDrive, pricing, and the MagSafe 2 power connector’s lack of backwards compatibility with the older MagSafe design.
Since the battery is glued in and cannot be easily disassembled for recycling (an EPEAT requirement), Apple received criticisms about the machine’s ability to be recycled. Greenpeace spokesman Casey Harrell said Apple “has pitted design against the environment—and chosen design. They’re making a big bet that people don’t care, but recycling is a big issue.”Wired also criticized Apple’s recyclability claims, stating “the design may well be comprised of ‘highly recyclable aluminum and glass’—but my friends in the electronics recycling industry tell me they have no way of recycling aluminum that has glass glued to it like Apple did with both this machine and the recent iPad.”
The Retina displays on the MacBook Pro have been criticized for “image retention,” usually when they were manufactured by LG.
The HP ProBook is a brand of affordable business notebooks made by Hewlett-Packard. The ProBook series are aimed at mainstream business users and are cheaper than the higher-end EliteBook series.
In April, 2009, HP introduced the ProBook s-series (standard/essential) notebooks, which consisted of the Intel powered 4410s, 4510s, and 4710s (14″, 15.6″, and 17.3″ screens, respectively) and the AMD powered 4415s and 4515s (14″ and 15.6″ screens, respectively).This was followed by the introduction of the 13.3″ ProBook 4310s in June of the same year.The s-series was updated in 2010 with Intel Core i3, i5, and i7 processors, a brushed aluminum case, chiclet keyboard, and multitouch ClickPad.Updates to the line in 2012 included a new exterior aluminum design.
Lenovo Y70 Touch
The Y70 Touch is one of Lenovo’s best touchscreen gaming laptops with a 10-point multitouch display & 4th Gen Intel® processors.
Large 17-inch touch display. JBL speakers and subwoofer provide good sound. Comfortable keyboard. Solid performance in gaming and productivity alike.
1.920 x 1.080 resolution and 10-point touch support. Touch is still a relatively rare offering in gaming systems, but it’s a welcome addition—Windows 8.1 is much more navigable and intuitive with a touch screen. The picture quality is quite good, with sharp details, accurate colors, and wide viewing angles. The sound is also good with JBL speakers, a built-in subwoofer, and Dolby software enhancement. When tested with the new Terminator Genisys movie trailer in 1080p, the picture looked great even in darker shots, and the sound was clear, whether rumbling with explosions, the new version of “I’d Love To Change the World,” or Arnold’s “I’ll be back.”