The success of portable computing this decade is due at least in part to the pioneering work of many companies in decades past.

Apple recently launched the iPad 2 to tremendous fanfare, and the device is being hailed as the latest and greatest portable computing device. Even though more powerful convertible tablet PCs were available years ago, the iPad has flourished thanks to its intuitive touch-based interface and a wealth of easy-to-install third-party applications. Apple sold around 15 million iPads in 2010, and the company looks poised to have a big year with the iPad 2.

Important milestones in portable computing include devices such as single-chip calculators, 'laptops' that weighed more than 10kg, digital organisers and even a few older Apple inventions. Here's a look at 18 of the most notable mobile computers.

1971: Busicom LE-120A 'Handy-LE' Calculator

Milestone: First pocket-size calculator

Legacy: It might seem strange to kick off a list of portable computing milestones with a calculator, but this little machine from Busicom was one of the first handheld devices that could carry out a computing function. So-called handheld calculators existed before this product, but the Handy-LE was truly the first calculator you could easily hold in your hand or fit in your pocket. The Handy-LE's small size was due to the single-chip calculator circuit - the Mostek MK610 - that carried out the device's computing functions.

Photo: Courtesy of Dentaku Museum

1978: Parker Bros Merlin Computer Toy

Milestone: Early mass-market computer toy

Legacy: It may have been a toy, but the Parker Bros Merlin was one of the earliest portable computers that many children growing up in the late 70s and early 80s encountered. The device had a simple microprocessor and could play six different games: Tic-Tac-Toe, Echo, Blackjack, Magic Square, Mindbender and Music Machine. The last game provided the device with limited programmability, allowing you to input up to 48 tones and rests and have the computer play back your composition.

Photo: Courtesy of Retroland

NEXT PAGE: Osborne 1 Portable Com

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

1981: Osborne 1 Portable Computer

Milestone: The first computer made for picking up and carrying with you (it doubled as a weight-training device)

Legacy: Although the Osborne 1 wasn't light at nearly 10kg, it was the very first computer designed for users to pack up and tote. The computer offered a five in diagonal screen, two full-size floppy drives, a keyboard that snapped on to the system, and a handle in the back for easy - but heavy - carrying.

Photo: Courtesy of Taringa.net

1982: Grid Compass 1100 Clamshell Laptop

Milestone: Considered the first clamshell laptop

Legacy: The Grid Compass changed portable computing forever when the manufacturer came up with the brilliant idea of having the display fold over the keyboard. That basic concept remains the standard in laptop design.

NEXT PAGE: TRS-80 Model 100 Portable PC

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

1983: TRS-80 Model 100 Portable PC

Milestone: Early portable computer popular with telecommuters

Legacy: Sold in the US by Radio Shack and weighing 1.5kg, Tandy's TRS-80 Model 100 was one of the first computers light enough for people to carry around on a daily basis. The Model 100 proved to be particularly popular with journalists. Microsoft co-founder Bill Gates said in an interview with the Smithsonian Institution in 1993 that one of the last machines he wrote a large amount of the code for was the TRS-80 Model 100.

1984: Psion Organiser Handheld Computer

Milestone: The first handheld computer

Legacy: This organiser, the first from UK-based Psion, was the earliest device that could truly be considered a handheld personal computer. The Psion Organiser included a calculator, a calendar and a BASIC-like programming language. Psion's handheld devices were predecessors of the open-source Symbian mobile phone operating system maintained by Nokia.

Photo: Courtesy of the rescue.org2.com

NEXT PAGE: Psion Series 3 Minicomputer

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

1991: Psion Series 3 Minicomputer

Milestone: First palmtop minicomputer

Legacy: An early ancestor of the netbook, the Psion 3 was a miniature clamshell personal organiser that featured a word processor, a spreadsheet, a contacts database, a sketch program, a calculator and a clock.

Photo: Courtesy of Old-Organizers.com

1996: Palm Pilot 1000 Digital Planner

Milestone: First popular digital day planner

Legacy: Psion devices and Apple's Newton may have come before it, but the Palm Pilot 1000 was the first truly popular personal digital assistant. The PDA let you keep a to-do list, a calendar, a contacts database and short memos all in a small, stylus-input-based handheld device. Later Palm devices were among the first to popularise 'beaming' information between devices using an infrared port. Palm's Graffiti handwriting-recognition technology also did a far better job at accepting stylus input than Newton and earlier handwriting systems did.

NEXT PAGE: Panasonic Toughbook CF-25 Laptop

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

1996: Panasonic Toughbook CF-25 Laptop

Milestone: The battle-ready laptop

Legacy: The Toughbook CF-25 laptop was housed in a sturdy aluminium-alloy case and designed to survive a 2ft drop. It could also perform under tough environmental conditions such as heat, dust and humidity. Battlefield commanders, police officers and emergency services were among the first to put the CF-25 to the test. The original tough-guy computer may be obsolete today, but the Toughbook line is still going strong.

Photo: eBay listing

1999: Apple iBook G3 Wi-Fi-enabled Laptop

Milestone: First consumer device to carry a Wi-Fi card

Legacy: Apple's iBook G3 was hailed not only for its candy-coloured design but also for being one of the first consumer laptops to sport a Wi-Fi card. Many other laptops soon came on the market with Wi-Fi capability, kicking off the era of wireless internet connectivity.

Photo: Courtesy of Redjar via Creative Commons

NEXT PAGE: Acer TravelMate

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

2002: Acer TravelMate TM-100 Laptop/Tablet Hybrid

Milestone: Early pen-based convertible laptop/tablet hybrid

Legacy: The TravelMate was one of the first devices to come loaded with Windows XP Tablet PC Edition. Acer's TravelMate 100 was also notable for being one of the first laptops that let users rotate the screen 180 degrees and lay it flat on the keyboard with the display facing out. Convertible laptops became a standard offering for anyone looking for a tablet PC. Despite Microsoft's enthusiasm for slates, however, the tablet concept wouldn't take off for another eight years, remaining a niche idea until Apple introduced the one-panel iPad in 2010.

Photo: Courtesy of Pen Computing

2002: RIM BlackBerry 5810 Handheld email machine/phone

Milestone: Early modern smartphone

Legacy: The BlackBerry 5810 was neither the first device to come out of Canada's Research In Motion nor the first PDA to include phone capabilities. But it was the first of RIM's handheld email machines to include a phone function, and it would lead to RIM's dominance of the enterprise smartphone market. The device popularised several technologies that users value in smartphones today, such as push email and end-to-end data encryption.

Photo: Courtesy of BlackBerry Today

NEXT PAGE: Samsung Q1

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

2006: Samsung Q1 Ultra-Mobile PC (UMPC)

Milestone: Early ultramobile PC

Legacy: The Samsung Q1 featured a 7in display, a 900MHz processor, and 500MB of RAM, and it ran a modified version of Windows XP. The UMPC form factor's popularity was short lived due to the device's high price (the Q1 cost £799) and the introduction of more successful touch-based smartphones and tablets in the following years. Nevertheless, the ability to pack a fair amount of computing power into such a small device was notable for the time. UMPCs are still being manufactured by companies such as OQO and General Dynamics.

Photo: Martyn Williams

2007: Eee PC netbook

Milestone: First netbook, early laptop with solid-state drive

Legacy: Netbooks may soon become irrelevant as a result of the dominance of tablet devices such as the iPad, but these mini-laptops were an important development in portable computing. They offered an inexpensive way to get your hands on a relatively usable laptop.

Around the same time as the Eee PC hit the market, the One Laptop Per Child campaign began offering cheap, durable laptops to children in developing nations. In the developed world, netbooks were soon followed by ultraportable laptops such as the MacBook Air and Dell Adamo. The Eee PC is also notable for using solid-state memory instead of a spinning hard drive. These days, many portable devices rely on SSDs instead of hard drives, including smartphones and Apple's new MacBook Air.

NEXT PAGE: Apple iPhone

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

2007: Apple iPhone smartphone

Milestone: Intuitive touch-based interface that turned the smartphone into a minicomputer

Legacy: Apple's first iPhone, with its intuitive interface and powerful computing ability, changed the way we think about smartphones. The handset's seamless integration with iTunes also made it an ideal device for listening to music or watching videos on the go. Before the iPhone, smartphones were typically difficult to navigate, had small displays combined with larger physical keyboards, and were often frustrating to use.

2008: Apple iTunes App Store

Milestone: Sparked the third-party application craze

Legacy: The App Store may not be a device, but it's hard to imagine what modern smartphones and tablets would be like without the introduction of Apple's third-party app scheme. Users have loved the variety of apps available for the iPhone (and later the iPad), including games, utilities, productivity applications, e-books and communication tools. Numerous competitors - including Google, Microsoft, Nokia, Palm and RIM - have tried to replicate Apple's App Store success.

NEXT PAGE: Apple iPad

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad

From the Busicom LE-120A calculator to the Apple iPad, we love tech gadgets that free us from our desks. Here are some of the most important portables we've carried around over the past 30 years.

2010 to 2011: Apple iPad 1 and 2

Milestone: First mass-selling tablet PC

Legacy: No one was really sure what to make of the iPad when it debuted. The device was too weak to be a laptop replacement, but too large to substitute for a smartphone. Currently the tablet serves as a complimentary piece of technology for home users who want to read, manage email, or watch a video without lugging around a laptop.

Professionals, meanwhile, are using the iPad to track medical charts or to give lectures and presentations. The touch-based one-panel tablet design is still in its infancy, but such devices seem poised to be a part of our lives for a long time to come.

Having sold around 15 million units in 2010, Apple's iPad has accounted for 83 percent of all tablet sales, thanks to its intuitive touch interface and vast array of easy-to-install apps. And Apple looks to continue the trend with the recently launched iPad 2 (shown here).

2011: Motorola Atrix 4G Smartphone

Milestone: Webtop/smartphone hybrid

Legacy: The Motorola Atrix 4G could very well represent the future of mobile and desktop computing. The device works as a conventional smartphone, but if you connect it to an external monitor, keyboard and mouse, it can run a full version of Mozilla's Firefox browser as well as any installed mobile apps. Business users can also access a virtualised Windows desktop on the Atrix 4G through Citrix XenApp.

The Atrix 4G is too new for us to say whether it will be a success or failure, but the handset may foreshadow a time when your smartphone can run a complete desktop system as well as a mobile OS.

See also: Buyers guide: Laptop, netbook or smartphone?

  1. Groundbreaking portable devices
  2. Osborne 1 Portable Computer
  3. TRS-80 Model 100 Portable PC
  4. Psion Series 3 Minicomputer
  5. Panasonic Toughbook CF-25 Laptop
  6. Acer TravelMate
  7. Samsung Q1
  8. Apple iPhone
  9. Apple iPad