PCI & ISA bus
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Transcript of PCI & ISA bus
G.H.RAISONI COLLEGE OF ENGINEERING( AN AUTONOMOUS INSTITUTE UNDER UGC ACT 1956 )
PCI & ISA BUS
Submitted by
Sushant burde (ETRX B-48)
Tarun dhiraj (CSE B-56)
Block diagram of a PCI bus system
Copro-cessor
CPU CacheMain
Memory
PCIBridge
Processor/Main Memory System
SCSI hostadapter
Interface toExpansion Bus
LANadapter
I/OGraphicsadapter
AudioMotionVideo
Bus Slot
PCI Bus
Expansin Bus (ISA/EISA)
Bus Slot Bus Slot Bus Slot
Latest Generation of PCI Chipsets
The PCI read transfer burst
The PCI write transfer burst.
The PCI Express Bus
• Point to point protocol– x1, x2, x4, x8, x12, x16 or x32 point-to-
point Link
• Differential Signaling
PCI Express Topology
ISA BUS
In 1982 when ISA BUS appeared on the first PC the 8-bit ISA bus ran at a modest 4.77 MHZ – the same speed as Intel 8088. ISA BUS is extremely slow by today's standards and not suited to the use of a graphical operating system like Windows. In 1984 the IBM AT was introduced using the Intel 80286; at this time the bus was doubled to 16 bits (the 80286's data bus width) and increased to 8 MHz (the maximum speed of the original AT, which came in 6 MHz and 8 MHz versions and 24 address lines).
ISA BUS
Bus width 8 - bit
Compatible with 8 bit ISA
Pins 62
Power +5 V, -5 V, +12 V, -12 V
Clock 4.7727266 MHz
Bus width 16 - bit
Compatible with 16 bit ISA
Pins 98
Power +5 V, -5 V, +12 V, -12 V
Clock 8.333333 MHz
8-bit ISA BUS 16-bit ISA BUS
ISA BUS
Original 8 bit ISA connectors
Additional connections converts to 16 bit ISA
VESA connectors
Describing the Read operation of the ISA
• CPU sends out a high on the ALE signal, then sends out the A0-A19 lines. On the address of the target port to be read will be latched. Then the BUS takes the -IOR signal to a low level. So that the addressed device will take a data byte to the D0-D7 data bus. The microprocessor will read then the data bus and take the -IOR signal to a high again.
ISA BUS
Address bus(32 bit)
Data bus (32 bit)
A0 to A31
D0 to D31
RD WR IO/M
Control bus
I/O bus (16 bit data)
Memory
• Intel• 80386D
X• CPU
Elimination of ISA Bus
The ISA bus is limited to 24 bits of address. 2^24 = 16 MBytes. It means that an ISA card that uses DMA cannot physically access memory beyond 16 MBytes of RAM. This is a limitation of the ISA bus. Motherboard gets 32-bit data from ISA BUS at two times. Meanwhile at this time ISA BUS declares “wait state” to the motherboard. Therefore ISA BUS may reduce System Performance.