To determine which monitor has better color and clarity, or to find out which key on your keyboard is malfunctioning, you can use two highly effective tools: MonitorTest and KeyboardTest. 
Keyboard Test
KeyboardTest is a unique keyboard testing tool available today. Once successfully activated, KeyboardTest will immediately recognize your keyboard type.
KeyboardTest presents its user interface in the form of a full keyboard. To test the keys, simply “swipe” across all the buttons on the keyboard. KeyboardTest will display a green grid mark on all functioning keys as soon as those keys respond properly. After “swiping” all the keys with KeyboardTest, you will quickly identify any non-functioning keys when the green test mark does not appear.
KeyboardTest also supports testing the functionality of mouse buttons and allows you to click the “Test LEDs” button to check whether the Num Lock, Caps Lock, and Scroll Lock lights are operational. To start a new test cycle, click the “Clear” button to erase previous test marks. KeyboardTest supports the testing of the three most common keyboard types today: the AT 107, and two compact keyboard types, Dell Int and Dell US. This tool proves to be extremely useful for stores specializing in second-hand computer parts.
Users can click here to download the trial version of KeyboardTest 2.2, which is only about 741KB, or purchase the official version at software stores.
MonitorTest
To check your monitor, download and install the small software MonitorTest. After activating MonitorTest, it will immediately provide you with some basic information about your monitor and the graphics card in your computer, including: bit color per pixel, total actual colors, maximum resolution, total pixels, refresh rate, operating frequency, type of graphics card, and production date… Your task is to use your eyes to compare or identify any defects in the monitor through various testing methods.
First, you should select the color display mode you wish to test in the “Select Video Mode” box. There are hundreds of screen color “modes” in the list, but you only need to select the default mode that you are currently using. The most common screen mode today is typically “1024 x 768 – 32bpp – 60 Hertz”.
In the “Select Test” box, the default test mode is set to “All Test,” which includes various tests of the display performance such as: Master Screen (testing perfection from all angles and color gradients); Black, Red, Green, Blue, White, Gray, Grid, Box, Gamma, Flicker, and the specific ratio of each color…
Click the “Start” button to begin testing the display performance of each color tone. Each color tone test will appear separately for you to evaluate, and to move to the next color tone test, simply click the “Next Test” button.
This tool, “MonitorTest,” is incredibly effective for comparing the image quality of different types of monitors, especially when you are shopping for used monitors.
PassMark Software is selling this tool for $24. Users can click here to download the trial version of MonitorTest 2.2, which is about 1.1 MB, or purchase the official version at software stores.
