from: http://joemygod.blogspot.com/2010/10/sony-kills-walkman.html
1. Sony Walkman
It’s amazing how handhelds have evolved over the decades. Perhaps the earliest portable gadgets were portable radio transistors that served for community broadcasts and military camps, until the famed lightweight and pocket-sized Sony Walkman™ hit the roads during the 1970s as the first commercially available portable audio cassette.
From: http://www.ogormans.co.uk
2. Sony Discman
The first CD-based Sony Walkman was released in 1984 and was initially called Discman. But with the Walkman trade name being more popular, it was soon used to refer to the subsequent products.
As the compact disc gained popularity in the 1980's, cassette players sold less especially in the Japan and Korea. The market became more interested in portable digital gadgets and manufacturers strived to innovate and experiment with various technologies that allowed built-in storage and retrieval drives besides the broadcast and playback features of the portable players.
From: http://ramilcvaliente.blogspot.com
3. MPMan MP3 Player
In 1997, MPMan developed the MP3 format which is a MPEG-1 Audio Layer 3 encoding used for compression of data. This allowed higher storage capacity for portable devices and even higher quality audio playback.
Although the MPMan MP3 player was not a popular brand, it was actually the precedent of today’s iPod.
from: http://www.pcmag.com
4. Apple’s IPod
Apple's Steve Jobs incites of iPod™ as "a whole new category of digital music player that lets you put your entire music collection in your pocket and listen to it wherever you go." Amazingly, this ultra-portable superslim pocket gadget stores up to 5GB or about 1,000 CD-quality songs and has a rechargable battery life of about 10 hours of nonstop music playing of various sound formats.
Making the most of MP3 technology, iPod broke into the street scene and slid right into almost everybody’s pockets.
5. Touchscreen handhelds
Uh-ah…it’s not Apple who made the first ever plausible touchscreen device in our world of gadgets, it was actually Hewlett-Packard who in today’s market dominates the world of printing.
HP-150™ wasn’t a touchscreen in the strict sense, being a CRT that had devices for infrared sensoring of non-transparent objects. The innovations later led to the creation of one of the best inventions as of yet: touchscreen handhelds like the iPad & numerous assortments of phones.
Sources:
http://upload.wikimedia.org/wikipedia/commons/9/98/WalkmanTPS-L2.jpg
http://t2.gstatic.com/images?q=tbn:ANd9GcROSSKKyTxl0WmVGwsYmmaKRpOuvXzbPsfNu4tloHJqSbXoxJ_M
http://www.pvp4u.com/images/iriverTI_IMP%201100_avportablemediaplayer.jpg
http://www.buzzle.com/articles/who-invented-the-mp3-player.html
http://images.apple.com/ipod/home/images/productbrowser/ipodclassic.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Hp150_touchscreen_20081129.jpg/220px-Hp150_touchscreen_20081129.jpg