Page 18 - Computer Science Class 11 With Functions
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1.3.4 Speakers/Headphones
A speaker or a headphone generates sound as output. A computer typically requires specialised hardware (a sound
card) to provide output in the form of sound.
Monitor
Speaker Headphone
Output Devices
Plotter Printer
Fig 1.5: Output Devices
A 3D printer allows for making a three-dimensional solid object from a digital file.
1.4 Memory Unit
A computer system's memory unit (also called a storage unit) is used to store data and instructions.
1.4.1 Units of Memory
The data is stored and processed in a computer using binary digits, often abbreviated as bits: 0 and 1. Thus a bit is the
basic unit of memory. Bits are grouped to form larger units of information. For example, a sequence of four bits forms
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a nibble. As each bit in a nibble can be 0 or 1, four bits lead to 16 (=2 ) different nibbles: 0000, 0001, 0010, 0011, 0100,
0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111. Thus, a nibble can express a number between 0
8
and 15. A sequence of eight bits forms a byte. Again, as each bit in a byte can be 0 or 1, a byte can express 256 (=2 )
different sequences. Thus, a byte is used to express a number between 0 and 255. The bytes can be further grouped
to form bigger units of memory. Table 1.1 shows different units of memory.
1 Bit = Binary Digit
8 Bits = 1 Byte
1024 Bytes = 1KB [Kilobyte]
1024 KB = 1MB [Megabyte]
1024 MB = 1GB [Gigabyte]
1024 GB = 1TB [Terabyte]
1024 TB = 1PB [Petabyte]
1024 PB = 1EB [Exabyte]
1024 EB = 1ZB [Zettabyte]
1024 ZB = 1YB [Yottabyte]
1024 YB = 1 Brontobyte
1024 Brontobyte = 1 Geopbyte
Table 1.1: Units of Memory
16 Touchpad Computer Science-XI

