The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition

BASICS OF COMPUTER SYSTEMS 31

are 100 locations in a memory device, 100 bytes are stored. We all have heard of memory

capacity being mentioned in terms such as bytes, kilobytes and megabytes. Now let us quantify

these terms. You will be hearing these terms throughout the use of this book.

A byte is 8 bits. A word is not really defi ned. It depends on the processor used. For the 8086,

a word size is 16 bits. A 32-bit processor may claim to have a word size of 32 bits. Memory

capacity is always specifi ed in bytes.

2

8

= 256 bytes

2

10

= 1024 bytes = 1KiloByte or 1KB

2

6

× 2

10

= 2

16

= 64 KB = 65, 536 bytes

2

10

× 2

10

= 2

20

= one Mega Byte (1MB) = 1024 × 1024 = 1,048, 576 bytes

2

10

× 2

20

= 2

30

= one Giga Byte (1 GB) = 1024 × 1024 × 1024 = 1,073, 741, 824 ...