CPU Chips The logical pinout of a generic CPU. The arrows indicate input signals and output signals. The short diagonal lines indicate that multiple pins are used. For a specific CPU, a number will be given to tell how many.
Dec 22, 2015
CPU Chips
The logical pinout of a generic CPU. The arrows indicate input signals and output signals. The short diagonal lines indicate that multiple pins are used. For a specific CPU, a number will be given to tell how many.
Buses
• Links device(s)• Internal to CPU or External• This chapter is external buses• Multiple buses in computer• Some buses run of other buses• Can be used for
– Control– Data – Address
Buses (cont)
• External buses are well defined to allow interconnect (Bus protocol)
• Examples– ISA– EISA– USB– FireWire
Buses
• Three types– Masters Active initiate transfer – bus drivers– Slaves Passive receive data – bus receiver– Both – both transceiver
May not match CPU
multiplexer
decoder
Bus Width
• Tradeoffs– Speed– Cost– Capabilities– Compatibility
ISA – 20 address lines – 1 MB
EISA - 32 Address lines - 4 GB
Speed
• Synchronous buses– Increase clock speed– Increase width
Problems
Compatibility
Bus skew
Multiplexing
Asynchronous Buses
• Not tied to clock
• Uses new technology
• More control lines
• Not as many chips are available
Bus Arbitration (1)
(a) A centralized one-level bus arbiter using daisy chaining.(b) The same arbiter, but with two levels.
Arbitration
• Only bus masters are concerned
• Two types– Centralized – some logic external to device
requesting access– Decentralized – logic in each device that
could request access
Bus Operations
• Single word or block transfer
• Read modify write cycle
• Interrupts
• Time critical priorities
Pentium 4
Logical pinout of the Pentium 4. Names in upper case are the official Intel names for individual signals. Names in mixed case are groups of related signals or signal descriptions.
Pentium 4
• 478 pins
• One corner is missing pins for alignment
• On board bus arbitration
• All transfers are on 8 byte boundary with 8 bytes at a time
• Controls power use to reduce heat
Pentium 4 Pipeline
• Bus Arbitration
• Request phase
• Error-reporting phase
• Snoop phase
• Response phase
• Data pahse
• Each phase uses different bus signals
UltraSPARC III
• RISC computer – 64 bit
• Designed for multiprocessor systems
• 6 internal pipelines – up to 14 stages
• 1368 Land Grid array package
• Up to 8TB of memory
• Address memory thru UDB II (UltraSPARC Data Buffer II)
ISA
• ISA Industry Standard Architecture
• Runs at 8.33 MHz
• PC 62 line bus + 36 Lines – ISA
• EISA (Extended ISA) 32 bit
Bandwidth Calculations
• 1024X768 screen with true color
• Requirement for moving video is 30 fps
• = 67.5 MB/sec of data for video only
• Because screen must be read/generated, actual requirement = 135MB minimum
• EISA has a maximum of 33.3 MB/sec
PCI
• Original PCI 33 mhz with 32 bit bus = 133 MB/sec
• PCI 2.0 66 mhz with 64 bit bus = 528 MB• Old PCI was 5.0 volts, new = 3.3 volts• APG added to offload video load from PCI• AGP 3.0 (8X) is 2.1GB• Master now call initiator• Slave now called target
The PCI Bus (1)Architecture of an early Pentium system. The
thicker buses have more bandwidth than the thinner ones but the figure is not to scale.
PCI Bus Transactions
Examples of 32-bit PCI bus transactions. The first three cycles are used for a read operation, then an idle cycle, and then
three cycles for a write operation.
USB
• For slower devices• No switches to set• Do not open case• Power from cable• 127 devices from Cable• Support real-time• No reboot necesssary• Inexpensive
USB
• 1.0 runs at 1.5 mbps
• 1.1 runs at 12 Mbps
• 2.0 runs at 480 Mbps
• 4 wires 2 for data, power and ground
• Time-sliced
• No interrupts
USB
• 4 types of frames– Control– Isochronous– Bulk – Interrupt
Frame consists of packets
data
token
handshake
special