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How is the bus classified? What's a system bus? The system bus is divided into different categories
What's the effect, one-way or two-way
What does the memory have to do with it
Bus classification:
:: by data: parallel transmission bus, serial transmission bus
• coverage by bus: computers (including external) mainlines, meteor control bus, network communications
Bus
• connected components: internal bus, system bus, communications bus
System bus: means the transmission of information between the major components of cpu, primary storage, i/o equipment
Line。
System bus classification:
Data bus: used to transmit data information between functional components, two-way transfer, bit
Numbers are related to machine length, store length
Address bus: mainly to indicate that source or destination data are stored on the data bus
Address of the unit or i/o device, one-way transfer, digits and
The number of storage units is relevant, the address line is n root, and the storage unit is
There's two of them
Control bus: used to send various control signals, single for any control line
Transfer to the control bus as a whole, two-way transmission is considered
3. 4 why set up bus quality controls? There are several types of centralized bus controls that are common
What are the characteristics, what's the fastest response time, what's the most sensitive to circuit failure
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Sensory
The transmission on the bus is initiated by the main device if multiple main devices are used simultaneously
The bus, with the master controller's judgement and arbitration logic in order of priority
Determine which main device uses the bus。
Three ways to control the centralized bus
• chain-based queries
1. Only a few lines are required to achieve bus control according to certain priorities
2. Easy to expand equipment
3. Be sensitive to circuit failure and low priority equipment may be difficult to obtain please
Timed query on the counter
1. Counts can start from 0, at which point, once the equipment priorities are fixed, the equipment
The priority is in descending order of zero, one, two... N and fixed
Counts can also start at the end point of the last count, i. E., a medium cycle. Square
Method, at which time the equipment uses a bus with equal priority
3 the initial value of the counter can also be programmed so that priorities can be changed at will
Modalities for independent requests
1. Rapid response
2. Flexibility of priorities [through procedural changes]
3. Large number of lines of control, more complex bus control
3. 5 interpretation of concepts: bus width, bus bandwidth, bus reuse, bus main equipment [or]
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Main module, bus from equipment [or from module], bus transmission cycle, bus
Communications control。
The width of the bus: the number of digits of binary numbers that the bus can transmit at a time
A bus bandwidth: is the total amount of data that this bus can transmit within a unit time,
It equals the product of the width of the bus and the frequency of work
Re-use of bus: refers to how data and addresses are transmitted on the same bus
Main module: a module that controls the bus and allows data exchange with other non-main module(s)
Equipment
From module: modules that cannot control the bus
Bus transmission cycle: complete and reliable mail completed for two components connected to the bus
Interest transfer time
Bus communications control: mainly to address how both parties are informed of the start and end of the transmission, with a view to:
How to coordinate with the communications parties
3. 6 comparative synchronous and rectangular communications
Synchronization of communications
Advantages: clear and uniform provisions and simple alignment between modules
Shortcomings: main, mandatory "synchronous" from modular time, must be timed
The requirement to complete the prescribed requirements and to use the same time limit for all from the module, this trend
It has to be the slowest part of a component with different speeds
The design of a public clock has a serious impact on the efficiency of the bus's work and has been designed. And..
There are limitations, lack of flexibility
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• distance communication
Advantages: allow inconsistent speed of modules and give designers sufficient flexibility and choice
Space
3. 10 what is the bus standard? Why set up bus standards? Current popular cursor
What's in it? What's in it and what's on it
Bus standards: a connection between the system and the modules, modules and modules
Standard interface
Reason for setting bus standards: to simplify the design of the system, batch quantification of module production,
To ensure that their performance is stable, of reliable quality and that they are transferable,
Easy to maintain
Standard types of bus: isa bus, eisa bus, vesa bus, pci bus
Agp bus, rs-232c bus, usb bus
Plug-in: users can easily install and dismantle outside without turning off
Unload, host can automatically configure system resources with external additions or deletions and install them
The installation, deletion and installation of the driver is automatic, and the usb bus has this
Characteristics
3. 14 the clock frequency of a bus is 8 mhz, with a bus cycle equal to a clock cycle。
If 16-bit data are transmitted in parallel in a bus cycle, ask how wide the bus is
Less
Solve: clock frequency is 8 mhz
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1 hour cycle 1/8 mhz = 0. 125 ms
Console transmission cycle 0. 125 ms
Bus width is 16bit=2b
Main bandwidth 2b*8mhz=16mbps
3. 15 in a 32-bit bus system, the clock frequency of the bus is 66 mhz, assuming the bus
The minimum transmission cycle is four hours, calculating the maximum data transfer rate for the bus. If
What measures can be taken to increase the rate of data transmission
Solve: bus width 32bit=4b
The bus's maximum data transmission rate is 4b* [66 mhz/4] = 66 mbps
To increase this rate of data transmission, it can be done without changing the clock frequency of the bus,
If you increase the width of the bus, you can also keep the width of the bus and increase the clock frequency of the bus
Rate。
3. 16 in the stagger system, the character format is: 1 starting point, 8 data bits
One check, two stop. If you want 120 characters per second, try pass
Send the porter rate and the bit rate。
Solve: porter rate = [1+8+1+2] *120 = 1440 bps
Bitrate = 8*120 = 960bps
