Information Technology Reference
In-Depth Information
KB
(kiloByte). This is defined as 2
10
bytes, which is 1024 B.
•
MB
(megaByte). This is defined as 2
20
bytes, which is 1024 kB, or 1 048 576 bytes.
•
GB
(gigaByte). This is defined as 2
30
bytes, which is 1024 MB, or 1 048 576 kB, or
1 073 741 824 B.
•
Table 2.1 gives a table with addressable space for given address bus sizes.
Table 2.1
Addressable memory (in bytes) related to address bus size
Address bus size
Addressable memory (bytes)
Address bus size
Addressable memory (bytes)
1
2
15
32 K
2
4
16
64 K
3
8
17
128 K
4
16
18
256 K
5
32
19
512 K
6
64
20
1 M†
7
128
21
2 M
8
256
22
4 M
9
512
23
8 M
10
1K*
24
16 M
11
2K
25
32 M
12
4K
26
64 M
13
8K
32
4G‡
14
16K
64
16GG
* 1K represents 1024
† 1M represents 1 048 576 (1024 K)
‡ 1G represents 1 073 741 824 (1024 M)
Data handshaking
Handshaking lines are also required to allow the orderly flow of data. This is illustrated in
Figure 2.4. Normally there are several different types of busses which connect to the system,
these different busses are interfaced to with a bridge, which provides for the conversion be-
tween one type of bus and another. Sometimes devices connect directly onto the processor's
bus; this is called a local bus, and is used to provide a fast interface with direct access with-
out any conversions.
The most basic type of handshaking has two lines:
•
Sending identification line - this identifies that a device is ready to send data.
•
Receiving identification line - this identifies that device is a device is ready to receive
data, or not.
