At 500 words per page, this means that a picture is worth 50,000 words. Floppy and hard disk drives are both input and output devices because the CPU can either read data from them or write data to them. The standard keyboard has 101 keys. A printer is an output device by which a computer can transfer information to paper. Common printer technologies include dot matrix in which the character is made of individual ink dots, laser in which output is like a photocopy machine, and bubble jet which shoots ink onto the paper by heated ink bubbles.
Most printers print in black and white although color printers are available.
Printers vary mainly in cost, quality, speed, and noise. 24 pin dot matrix printers are most common but laser printers are becoming cheaper and therefore more prevalent. Print quality is best with a laser printer, but very acceptable with a good quality dot matrix. Speed varies from 60 to 400 characters per second for dot matrix and ink jet printers and from 4 to 8 pages per minute for laser printers. Laser and ink jet printers are quietest but good quality dot matrix printers have acceptable noise levels.