数字电路与逻辑设计13PPT课件下载推荐.ppt

1、,Digital FundamentalsTenth EditionFloyd,Chapter 13,2008 Pearson Education,Summary,Computer Block Diagram,The central processing unit（CPU）controls the operations by issuing a fetch to memory for an instruction,then executes it.,Memory stores instructions and data until needed by the CPU.,The ports ar

2、e the I/O connections to the peripherals.,The buses are groups of conductors with a common purpose.,Peripherals are devices for inputting or outputting information.,Summary,Software,Software is all of the instructions that determine what operations are performed.,System software is the operating sys

3、tem of the computer and acts as the system manager.,Application software includes the various programs used to accomplish a task.,The BIOS is a portion of the operating system called“firmware”because it is a permanent part of the system software in ROM（read-only memory）.,Summary,Microprocessors,Four

4、 blocks are common to all microprocessors.These are:#,ALUPerforms arithmetic and logic operations,Instruction decoderTranslates the programming instruction into an address where microcode resides for executing the instruction Register arrayA group of temporary storage locations within the processor,

5、each with special features Control unitSynchronizes the processing of instructions,Arithmetic logic unit（ALU）,Instruction decoder,Register array,Control unit,Microprocessor,Summary,Microprocessor Buses,Three buses for microprocessors allow data,addresses and instructions to be moved.,The address bus

6、 is used by the microprocessor to specify a location in memory or external device.Some processors have 64 address lines and can access 1.8 x 1019 locations.,The data bus transfers data and instruction codes to and from memory and I/O ports.,The control bus coordinates operations and communicates wit

7、h external devices.,Summary,Microprocessor Programming,Microprocessors work with an instruction set that allows it to function.Although the instruction set within the processor is binary,programmers work with English-like commands,which are divided into seven groups.These are:#,Data transfer Arithme

8、tic and logicBit manipulationLoops and jumpsStringsSubroutines and interruptsControl,Summary,Multicore Processors,The Intel microprocessors up through the Pentium were all single core processors,meaning they had only one microprocessor in an IC.,Many newer processors have more than one core on a sin

9、gle IC.Multicore processors can execute more than one instruction at a time.This process is also called multiprocessing.,System bus,Processor core,Processor core,Cache,Cache,two processors work on an image at the same time to adjust the contrast.The work is sectioned so that each processor works on

10、only one part.,Example,An example of multiprocessing is when,Summary,Multitasking,Multitasking is a technique that allows a computer to perform more than one task.Unlike multiprocessing,the work only appears to be simultaneous because of the speed of the processor.,One type of multitasking parcels t

11、ime slices on the processor for each program this is called preemptive multitasking.Another type of multitasking is done when the program controls the processor this is called cooperative multitasking.,Multithreading is a variation on multitasking,where different parts of the same program are execut

12、ed simultaneously.,Summary,Operations,Microprocessors execute programs by repeatedly cycling through three basic steps:#,Execution unitEU,Executes instructions,Bus interface unitBIU,Fetches instructions,Reads operands,Writes results,System buses,8086/8088 Microprocessor,FetchDecodeExecute,The proces

13、sor has two internal units,the EU and the BIU,as shown in the figure:#,Summary,Operations,While the EU is executing instructions,the BIU is fetching the next instruction from memory,and storing the next instruction in a high speed memory called the cache.,Execution unitEU,Executes instructions,Bus i

14、nterface unitBIU,Fetches instructions,Reads operands,Writes results,System buses,8086/8088 Microprocessor,In the Pentium processors,two execution units（EUs）allow instructions that are independent of each other to execute at the same time.,The following slide shows the architecture of the 8088 proces

15、sor,Summary,Summary,Addressing,Intel chose a innovative way of generating 20-bit physical addresses in the 8088 and subsequent processors.,The physical address is formed by combining a 16-bit address in a segment register with a 16-bit address in a general register.The addresses“overlap”as shown,wit

16、h an implied 00002 on the right side of the segment register（shown in blue）.,16-bit segment base address,16-bit offset address,20-bit physical address,Segment register,General register,Summary,Addressing,Segment/offset addressing allows 64k blocks of code to be relocated in memory by changing only the segment address.,Example,Assume IP=20A016 and CS=B20016.What is the location of the start and end of the block?#What physical address is formed?#,Solution,The addressing is diagramed:#,Contents of CS,impl