The computer keyboard is the most under-appreciated component of the computer. Most tech-heads focus on spending several hundreds of dollars on the fastest and most powerful multi Mhz or Ghz processor or the biggest and brightest LCD screen. In reality, the one part of the computer that gets our most physical contact is the COMPUTER KEYBOARD. How many times a day do you touch a keyboard (number of characters typed) vs the number of times you touch your computer's internals?
As a computer system administator in real-life, I typically spend 10-12 hours at a computer. The last time I checked, I could type as fast as 100 - 110 words per minute. I have always needed an industrial-strengh keyboard. In November of 1984, I was able to purchase my first IBM PC 5170PC/AT (Intel 80286 processor at 8.0 Mhz with a 30MB (0.03 GB) hard drive, and 512K (0.5MB) of RAM for $9000. Little did I know that I would still be looking forward to using the same keyboard in 2004 (i.e., 20 years later).
Very few people today would think of spending $9000 on an average desktop computer. Today's new entry-level computers (Intel Pentium 4, 2.66Ghz, 40GB of hard drive, 256MB of RAM) start at $449. Computer manufacturers bundle these systems with lightweight keyboards. As a cost-savings measure (in other words, in order to maximize their profit) they can not justify anything more than a $9 keyboard. Personally, as a computer professional, the first thing that I do when I setup a new computer for myself, is re-attach my very durable IBM 04-Feb-1986 model M keyboard (serial #35005).
Ergonomic experts say that an effective keyboard design is one in which has a "soft touch" or is a "quiet key" and does not make excessive noise when keys are pressed. Personally, when I type on a typical "rubber-dome" $9 keyboard, I find that my fingers are more stressed and I find that I type slower because I'm not sure if my fast fingers have finished hitting the correct key.
Technically speaking, keyboards are differentiated by the types of key switches used. Key switches are the part of the keyboard which allow the user to press an individual key and converts mechanical force is into an electrical signal. When you type on an average "rubber dome" keyboard, each key press on a plastic key is pushing down an elastic rubber pad with a carbon center to make contact with a plastic sheet with conductive points. These keyboards are cheap to mass-produce. However, the typical feedback that a user looks when typing to verify that a key has been pressed, is the visual appearance of a letter or number on the screen.
Mechanical key-switch keyboards are technically superior because they provide visual, tactile and auditory feedback. The most popular and widely available mechanical keyswtich keyboard is the IBM model M keyboard (first produced in 1986). Its keyswitches change mechanical force into electrical signals through the use of "buckling springs". When you press an individual key, you are physically applying increasing force (approximately 30-40 grams of force) against a coiled spring. The spring provides sufficient resistance, so that you can quickly move your fingers across the keyboard and not cause an accidental or inadvertent key press. Once the spring travels a particular distance (appox. 2.5-3.5mm), the spring reach the "catastrophic buckling" point and produces an audible click. The spring moves an actuator back and forth between the open and closed position, and this signals to the computer that a particular key has been pressed.
In 1986, IBM first released the model M keyboard. Its keys were similar to that of a typewriter with "significant travel during actuation of the switch and even overtravel after actuation." (US Patent, 3,842,229). The use of a mechanical switch keyboard which allows users to both hear auditory feedback "clicks" and feel "keyboard resistance" as they type.
The IBM keyboard division was later moved to Lexmark in the 1990s. Then later Lexmark decided to focus on the printer business, and now Unicomp still builds, sells and supports model M keyboards.