Presentation on theme: "Bus Interface ISA (Industry Standard Architecture) VESA local bus"— Presentation transcript:
1 Bus Interface ISA (Industry Standard Architecture) VESA local bus (Video Electronics Standards Association)PCI (peripheral component interconnect)USB (Universal Serial Bus)AGP (Advanced Graphics Port)
2 Slide ObjectivesDetail pin connections and signal connections on the ISA, VESA local, and PCI buses.Develop simple interfaces to the ISA, VESA local and PCI buses.Program interface places on boards that connect to the ISA, VESA local, and PCI buses.Describe operation of the USB and develop some short programs that transfer data.Explain how the AGP increases the efficiency of the graphics subsystem.
3 ISA Been around since the start of the IBM PC (1982) Originally an 8-bit standard, now 16-bit. There was a 32-bit EISA (Extended), goneMost PCs have an ISA slot on the mainboard that can accept either an 8-bit of a 16-bit ISA printed circuit card.32-bit printer circuit cards are more often PCI, or in some older 486s, the VESA cards.
4 ISA / EISA / VESA local Clocking speed 8 MHZ too slow!! EISA -32-bit modification of ISA (386-PentiumII had 32-bit data buses)Both ISA and EISA run at 8 MHztoo SLOW!VESA and PCI both run at 33 MHz.Most common application for EISA bus is as a disk controller or as a video graphics adapter. Both apps benefit from the wider bus width because the data transfer rates for these devices are high.
5 VESA local Much better approach to 32-bit interfacing Common for video and disk interfaces to the 486 PC
6 PCI PCI -Peripheral Component Interconnect Only bus found in the newest Pentium II systems. (Most systems also have ISA, but as an interface for older 8-bit and 16-bit interface cards).Has replaced VESA bus.Has plug and play(PnP) characteristicsHas the ability to function with a 64-bit data bus.Most often used for interfacing I/O componentsMemory could be interfaced, but would operate only at a 33MHz rate with Pentium (half the speed of the redient local bus of the Pentium)
7 Plug and PlayPCI interface contains a series of registers, located in a small memory device on the PCI interface, that contain information about the board.This memory can provide PnP characteristics to the ISA bus or any other bus.Information in registers allows computer to automatically configure the PCI card.
8 Bus Structure of the Pentium II Pentium II ProcessorLocal Bus MHz or 100MhzAGP VideoAGP Bus 66MHz440LX or 440BX Chip SetMemoryPCI Bus 33MHz or 66 MHzLocal Frame BufferPIIX4 BridgeI/OUSB Bus MbpsISA Bus 8 MHzBus Structure of the Pentium II
9 PCI BridgeNot just buffers between PCI and processor busses. INTELLIGENT!Capable of grouping single data requests into bursts and then exchanging those bursts with memory and I/O devices.Ability to transfer an unlimited number of bytes in a single burst – even though processor itself may be limited to a much smaller size (one cache line)Each PCI device has a latency timer that defines longest time that device is allowed to control the bus.
10 PCI Bus OperationThe data bus lines use a multiplexing scheme to which connector pins are multiplexed as address and data pins.A PIC transaction takes place between a master (a device takes control of the system buses), and a target (a device that only responds to access requests).
11 BUS Access Read cycle takes three clock pulses Write cycle Output addressSwitch lines from address to dataTransfer dataWrite cycleAddress lines do not have to turned aroundOnly requires two clock cycles.
12 Bus Commands16 different commands (commands are multiplexed on the C/BE3’-C/BE0’) lines and output during the address phase of each bus cycle.INTA sequenceI/O read accessI/O write accessMemory read accessMemory write accessDual addressing cycle (64 bits on 32-bit data bus)Line memory read access (line of cache (greater than 32 bits)
13 DMA and interruptsBus Master concept of PCI eliminates necessity for DMA controller (still used)Bus master shuts down system board buses and communicates with adapters via bus slots.
14 PCI Adapters Support 3.3V, 5 V and Universal Separate slot arrangements for 3.3 and 5v. Universal adapters can work in either slotEach PCI card contains a 256-byte configuration memory. 64 bytes header (type of card, manufacturer, revision level, current status of card, cache line size in 32-byte units, and bus latency). Remaining bytes are card specific.
15 Plug and PlayConfiguration memory of units on PCI bus allow system to scan through devices and assign each device a unique base address and interrupt level.
16 I/O Buses SCSI (Small Computer Systems Interface) Parallel bus used to peripheral such as hard drives, tape drives, CD_ROM players.1 to 10MB/sec (PCI around 275MB/sec transfer rate)Intelligent busAccepts high level commands from processor and then transfer information without host participation.Allows parallel processing
17 SCSI Can accomodate 16 devices(SCSI-3) Must have host adapter (typically no.7)Devices connected in a daisy chain fashion with terminating plugs connected to each end of cable.
18 USB (Universal Serial Bus) Current ISA sound cards use internal PC power supply (generates a large amount of noise).USB allows sound cards to have their own power supplyEasy to connectAccess to up to 127 different connections through a 4 connection serial cable.Apps: keyboards, sound cards, simple video-retrieval devices, modems.Data transfer rates are 12Mbps full speed, 1.5 Mbps slow speed operation.
21 Root: primary controller Hub: allows the connection of multiple USB devicesEndpoint: Source or sink of information within a USB deviceA USB device that contains an ENDPOINT (source/sink of data) is called a ‘function’.A USB device can be just a function, just a hub, or both a hub and a function.
23 Pipes When attaching to a hub, host assigns a device an address. Characteristics of connection make up pipeSpeedDirectionRequired bandwidthError-handling capabilityTransfer typeMaximum packet sizeThe endpoint of the device communicates with the host. (endpoint 0 is for device initialization and configuration)
24 Bus Protocol Data transferred in packets Synchronous serial format Clock signal is encoded into data patternPackets are variable lengthIncludes:Sync field, packet id, Information field, and CRC
25 Data transfers Control Bulk (Text data for printer) Interrupt (mouse clicks)Isochronous (voice, music)
26 USB Connector 4 pins Biphase signals 5 v -Data +Data Ground When +data are at 5.0V, -data are at zero volts and vice versa
27 Physical InterfaceDifferential Signaling, Half duplexFull Duplex: data transmission can occur in both directions at the same timeHalf Duplex: data transmission can go in only one direction at a time
28 USB DataBiphase signals generated using a differential line driver (transceiver) with noise suppressionUses NRZI encoding (non-return to zero, inverted) for transmitting packets.Signal level does not change for transmission of logic 1sSignal level is inverted for every change to a logic 0Uses bit-stuffing for synchronizationA logic 0 is added after 6 continuous 1s in a rowData is transmitted LSB to MSB.
29 USB Commands Stop and Wait Flow control used host must wait for ACK, NAK before transferring additional data packetsSync (80h), PID sent first4 Types of Packets (Data, token, handshaking, and start-of-frame)2 types of CRC used (5-bit and 16-bit)ACK, NAK tokens used to coordinate transfer of packets.
30 PID Codes PID Name Type Description E1h OUT Token Host->function transactionD2hACKHandshakeReceiver accepts packetC3hData0DataData packet PID evenA5hSOFStart of frame69hINFunction -> host transaction5AhNAKReceiver does not receive packet4BhData1Data packet PID odd3ChPRESpecialHost preamble2DhSetupSetup command1EhStallStalled
31 Types of Packets on USB Token 8 bits 7 bits 4 bits 5 bits PID ADDR 8 bits7 bits4 bits5 bitsPIDADDRENDPCRC5Start of Frame Packet11 bitsFrame NumberData Packetbits16 bitsDataCRC16Handshake Packet
32 Accelerated Graphics Port Designed specifically to all high-speed transfers between video card frame buffer and system memory.Operates at bus clock frequency of the microprocessor.Maximum data transfer is 528MBps(2X)Max data rate for 4x system is 1GBpsPCI bus has max data rate of 100MBps