What does Peripheral Component Interconnect Bus
(PCI Bus) mean?
A Peripheral Component Interconnect Bus (PCI
bus) connects the CPU and expansion boards such as modem cards, network cards
and sound cards. These expansion boards are normally plugged into expansion
slots on the motherboard.
The PCI local bus is the general standard for a PC expansion bus, having replaced the Video Electronics Standards Association (VESA) local bus and the Industry Standard Architecture (ISA) bus. PCI has largely been replaced by USB.
The PCI local bus is the general standard for a PC expansion bus, having replaced the Video Electronics Standards Association (VESA) local bus and the Industry Standard Architecture (ISA) bus. PCI has largely been replaced by USB.
Features of PCI Bus:
The various features of PCI Architecture are given below:
Synchronous Bus Architecture: PCI is a synchronous Bus . All data transfers in PCI bus takes place according to a system clock. The first PCI which was launched by Intel , supports 33 Mhz maximum clock rate while the newer PCI Buses now supports maximum clock frequency of 66 MHz.
64 Bit Addressing: PCI Bus also supports 64 bit addressing. With PCI Bus, 64 Bit addressing can be implemented with the same 32 Bit connector. Dual address cycles are issued in which the lower order 32 bits addresses are driven onto during the first address phase and higher order 32 bits are driven onto during a second address phase. It does not requires a longer connector with additional 32 bit data signals (As required by the 64 bit data bus.)
Linear Burst Mode Data Transfer: PCI supports the feature of 'Burst Data Transfer'. With Burst Data Transfer, the data can be transferred at very high speeds. In Burst Data Transfer, a single address cycle can be followed by multiple data cycles. Thus , in Burst Data Transfer, Data is read and written to a single address location, which goes on automatically increment. In short, the data will be present on the bus, on each clock cycle. With this, we can achieve very high data transfer speeds that is 266 MB/sec for 32 bit data. With each clock cycle, a new data will be placed on the bus. If the cycle frame signal is active only for one data cycle, an ordinary transfer takes place. But if it is active for multiple clock cycles then the Burst Data Transfer takes place.
Large Bandwidth: PCI bus has much larger bandwidth than its previous buses (ISA, EISA and MCA). It can handle both 32 bit as well as 64 bit data. For 32 bit data, the maximum bandwidth will be 132 MB/sec which becomes more when Burst Data Transfer mode is used . It comes out to 364 MB/sec when Burst Data Transfer is used. Thus the bandwidth of PCI bus is very larger.
Synchronous Bus Architecture: PCI is a synchronous Bus . All data transfers in PCI bus takes place according to a system clock. The first PCI which was launched by Intel , supports 33 Mhz maximum clock rate while the newer PCI Buses now supports maximum clock frequency of 66 MHz.
64 Bit Addressing: PCI Bus also supports 64 bit addressing. With PCI Bus, 64 Bit addressing can be implemented with the same 32 Bit connector. Dual address cycles are issued in which the lower order 32 bits addresses are driven onto during the first address phase and higher order 32 bits are driven onto during a second address phase. It does not requires a longer connector with additional 32 bit data signals (As required by the 64 bit data bus.)
Linear Burst Mode Data Transfer: PCI supports the feature of 'Burst Data Transfer'. With Burst Data Transfer, the data can be transferred at very high speeds. In Burst Data Transfer, a single address cycle can be followed by multiple data cycles. Thus , in Burst Data Transfer, Data is read and written to a single address location, which goes on automatically increment. In short, the data will be present on the bus, on each clock cycle. With this, we can achieve very high data transfer speeds that is 266 MB/sec for 32 bit data. With each clock cycle, a new data will be placed on the bus. If the cycle frame signal is active only for one data cycle, an ordinary transfer takes place. But if it is active for multiple clock cycles then the Burst Data Transfer takes place.
Large Bandwidth: PCI bus has much larger bandwidth than its previous buses (ISA, EISA and MCA). It can handle both 32 bit as well as 64 bit data. For 32 bit data, the maximum bandwidth will be 132 MB/sec which becomes more when Burst Data Transfer mode is used . It comes out to 364 MB/sec when Burst Data Transfer is used. Thus the bandwidth of PCI bus is very larger.
What is Address Bus, Data Bus and Control
Bus in Microprocessor | What are the differences between them:
Microprocessor is
processing device of every computing device. It is like an artificial brain. It
needs to communicate with outer world. for example, It needs to communicate
with Input devices to get data,it needs to communicate with memory to process
data according to instructions written in memory and finally it needs to
communicate with output devices to display the output on O/P devices. To
communicate with external world, Microprocessor make use of buses. There are
different types of buses used in Microprocessor:
Address Bus: It is a group of wires or lines that are used to transfer the addresses of Memory or I/O devices. It is unidirectional.In Intel 8085 microprocessor, Address bus was of 16 bits. This means that Microprocessor 8085 can transfer maximum 16 bit address which means it can address 65,536 different memory locations. This bus is multiplexed with 8 bit data bus. So the most significant bits (MSB) of address goes through Address bus (A7-A0) and LSB goes through multiplexed data bus (AD0-AD7).
Data Bus:As name tells that it is used to transfer data within Microprocessor and Memory/Input or Output devices. It is bidirectional as Microprocessor requires to send or receive data. The data bus also works as address bus when multiplexed with lower order address bus. Data bus is 8 Bits long. The word length of a processor depends on data bus, thats why Intel 8085 is called 8 bit Microprocessor because it have an 8 bit data bus.
Also Read:
Control Bus: Microprocessor uses control bus to process data, that is what to do
with the selected memory location. Some control signals are Read, Write and Opcode fetch etc. Various operations are performed by microprocessor with the help of control bus. This is a dedicated bus, because all timing signals are generated according to control signal.
Address Bus: It is a group of wires or lines that are used to transfer the addresses of Memory or I/O devices. It is unidirectional.In Intel 8085 microprocessor, Address bus was of 16 bits. This means that Microprocessor 8085 can transfer maximum 16 bit address which means it can address 65,536 different memory locations. This bus is multiplexed with 8 bit data bus. So the most significant bits (MSB) of address goes through Address bus (A7-A0) and LSB goes through multiplexed data bus (AD0-AD7).
Data Bus:As name tells that it is used to transfer data within Microprocessor and Memory/Input or Output devices. It is bidirectional as Microprocessor requires to send or receive data. The data bus also works as address bus when multiplexed with lower order address bus. Data bus is 8 Bits long. The word length of a processor depends on data bus, thats why Intel 8085 is called 8 bit Microprocessor because it have an 8 bit data bus.
Also Read:
Control Bus: Microprocessor uses control bus to process data, that is what to do
with the selected memory location. Some control signals are Read, Write and Opcode fetch etc. Various operations are performed by microprocessor with the help of control bus. This is a dedicated bus, because all timing signals are generated according to control signal.
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