苹果公司在不足一千美元的价位推出了 ipad ，对很多苹果迷是个惊喜。惊喜之余，也有一些遗憾。
先说说 ipad 的好处。 ipad 基本是一个大 iphone 。 iphone 在手机里一枝独秀，触摸屏非常好用，可惜我的手机公司不是 AT&T ，只能干瞪眼。 Ipad 一出，那些电子相框，电子书阅读器之类的东西的末日就算到了。 Ipad 的设计和用户界面自有其独特的吸引人之处，特别是用惯 iphone 的用户更容易上手。 Ipad 的电池能坚持 8 个小时，也是优于一般手提电脑的一个卖点。自从见到 iphone 和那种不用翻盖的触摸屏手提电脑，我就在想如果苹果能做一款触摸屏手提电脑就好了，屏幕有个 8-10 寸，即方便携带，又不太费眼。现在果然它就上市了。 Ipad 的重要意义还在于，它有可能改变大家使用鼠标和键盘操作电脑的习惯。要知道，同时使用鼠标和键盘实在不是很方便，携带也不方便。也许最终有一天电脑的操作会变成用手指头在屏幕上按来按去。
Ipad 遭到批评指出大致有几点。一个是接口不全，特别是没有 HD 电视接口， USB 接口也不方便。再有一个是软键盘不好用。还有一个是不能很方便地同时运行多个程序。还有一个小问题是没有摄像头。
我想出的改进方法是做双板双屏，一个主板是 ipad ；另一个辅助板上另有一个屏幕，一块电池，还有 DVD-R ， GPS ，摄像头以及更多的接口。这样一来， ipad 本身可以独立使用，但是，加上另一个板则可以用一个屏幕看 DVD 或电子书，另一个屏幕打网络电话或上网浏览网页。如果需要处理文字，则辅助板可以横过来调用更大的软键盘。
写到这里，上网查了查，原来有些电脑制造商已经生产了不少类似的东西。这种产品叫Slate PC或 Tablet PC，中文叫平板电脑。比如三星就有一款，不到一千美元，但是看着屏幕比较小，CPU速度才1G左右。还有一些防水防震的产品也很有吸引力，不过仔细想想实用性并不大，谁没事儿老折腾手提电脑玩啊。那些高端的平板触摸屏手提电脑价位在两三千美元。惠普有一两款做得挺漂亮。
下面的解释是从维基百科贴过来的，介绍得挺全面。太长了，我就不翻译了。
Booklets
Booklet PCs are dual screen tablet computers that fold open like a book. A typical Booklet PC is equipped with multitouch screens and pen writing recognition capabilities. They are designed to be used as a digital day planner, internet surfing device, project planner, to watch videos, live TV, play music, and for e-reading.
Slates
Slate computers, which resemble writing slates, are tablet PCs without a dedicated keyboard. For text input, users rely on handwriting recognition via active digitizer, touching the screen with a fingertip or stylus or by using an external keyboard which can usually be attached via a wireless or USB connection.
These tablet PCs typically incorporate small (8.4–14.1 inches/21–36 centimetres) LCD screens and have been popular for quite some time in vertical markets such as health care, education, and field work. Applications for field work often require a tablet PC that has rugged specifications that ensure long life by resisting heat, humidity, and drop/vibration damage.
This added focus on mobility and/or ruggedness often leads to elimination of moving parts that could hinder these qualities.
Convertibles
Convertible notebooks have a base body with an attached keyboard. They more closely resemble modern laptops, and are usually heavier and larger than slates.
Typically, the base of a convertible attaches to the display at a single joint called a swivel hinge or rotating hinge. The joint allows the screen to rotate through 180° and fold down on top of the keyboard to provide a flat writing surface. This design, although the most common, creates a physical point of weakness on the notebook.
Some manufacturers, however, have attempted to overcome these weak points. The Panasonic Toughbook 19, for example, is advertised as a more durable convertible notebook. One model by Acer has a sliding design in which the screen slides up from the slate-like position and locks into place to provide the laptop mode.
Convertibles are by far the most popular form factor of tablet PCs, because the convertibles still offer the keyboard and pointing device of older notebooks, for people who are unsure about the practicality of using the pen as the primary method of input.
Hybrids
Hybrids, coined by users of the HP/Compaq TC1000 and TC1100 series, share the features of the slate and convertible by using a detachable keyboard which operates in a similar fashion to a convertible when attached.
This is not to be confused with slate models that have a detachable keyboard—detachable keyboards for pure slate models do not rotate to allow the tablet to rest on it like a convertible.
With a loyal following, the hybrid form factor has recently received updates after the TC1100. HP has launched an array of tablet pc convertible notebooks over the last few years, the latest being the tx2 which brings multi-touch capabilities to a consumer-aimed notebook.
