PowerPoint Slideshow about 'Advanced Microprocessors' - omer
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Growth from 16 bits to 32 bits did not bring entirely new architectures, as did the change from 4 bits to 8 bits, or the change from 8 bits to 16 bits.This permits programs from earlier microprocessors to run (usually a lot faster) on the new-generation microprocessor.
The advanced microprocessors are very powerful computing devices.
Typically, products which use these microprocessors are configured as general-purpose computers. CPU is connected to a bus along with memory, mass storage, general-purpose I/O, and a user interface. The user interface include an graphic display system and data entry system.
The general purpose architecture lets you use a wide variety of general-purpose software to make the unit do the job you need to perform.
Dedicated systems with advanced microprocessors typically need a great deal of computing power. For example, the 32-bit microprocessors are very popular for graphic display systems. A graphic presentation can be described as a multidimensional array with x and y dimensions describing the different points of the display. The z axis is used to define attributes such as color and intensity. To manipulate these images, you must quickly process multidimensional arrays.
Often products using advanced microprocessors also require sophisticated operating and application software.All of this means that, to understand and advanced microprocessor-based system, you may require more system knowledge than hardware knowledge.
One of the common applications for advanced microprocessors is with multi-user and multi-tasking operating systems.A multi-user operating system allows more than one user to appear to use the CPU at one time.Likewise, a multi-tasking operating system allows more than one task to appear to use the CPU at one time.
When a microprocessor is used in this mode, it is important to make sure that the individual users or tasks do not have access to the program performing the switching between users or tasks.
To do this, an advanced microprocessors offer a special way of operating which is called supervisory, protected, or privileged mode. The advanced microprocessor may have access to a number of special instruction, additional registers and other features.
Often virtual memory techniques is used where a software require access to large quantities of data.These data are much larger than the amount of physical memory available to the processor. The additional memory space is really on a disk, but through sophisticated memory addressing techniques. Advanced microprocessors often include special instructions and internal hardware to ensure the programs work properly.
During the late 1970s, Intel introduced the 8088 and 8086. Internally, these two 16-bit microprocessors have identical architectures. The difference between the two is the size of the external data bus.The 8088 has an 8-bit external data bus, and the 8086 uses a 16-bit external data bus.
In 1981 IBM introduced a PC based on the Intel 8088.
The 8088 and 8086 evolved into faster versions with wider external data buses, versions with greater memory addressing space, versions with advanced computing functions, and versions which process 32-bit data words.Because these versions also have a very similar architecture, they have a common numbering system.
8086 and 8088 were introduced in the year 1978. When it came time to pick a 16-bit microprocessor for the first IBM PC, the Intel 8088 was chosen because its 8-bit data bus made it easy to use the low-cost 8-bit peripheral devices built for use with the 8080/8085 and other 8-bit microprocessors.
The next major introduction was the Intel 80286. IBM introduced the PC/AT (personal computer/ advanced technology) version of its PC using the 286 in 1984.
One of the features introduced with the 286 was real and protected modes of operation. In the real mode, the processor can address only 1 Mbytes of memory, whereas in the protected mode it can address 16 Mbytes.
Another new feature was the ability to work with up to 1Gbyte of virtual memory, and yet another feature added hardware multitasking.
The 80386 was a major next step in the X86 family. The 80386 is a full 32-bit microprocessor. It has a 32-bit data bus and a 32-bit address bus, and it uses 32-bit internal registers.
The base 386 internal architecture is, in many ways, very much like the 8088, 8086, and 286 architectures. The major difference in the base architecture is that there are a few more registers and some register sets are now 32 bit rather than 16 bit.
Intel introduced a special version of the 386 called 386SX. It uses a 16-bit data bus. The original 80386 processor was renamed the 386DX. In addition to 32-bit processing, the 386 microprocessors offered advanced virtual memory, advanced protected mode. And higher speed.
Another variation of the 386DX is the 386SL. This is a low-power version. The 386SL can operate on either 3 or 5Vdc and has special power-management circuits which allow the processor to shut down when not being used.
Other versions of 386 are the 386DX2 and 386DX4. The DX2 version doubles the internal clock speed, thus speeding up many calculations and operation. The I/O, however continues to operate at lower speed, so there are no external interface problems if a 386DX2 is substituted for a 386DX. The 386DX4 triples the internal clock speed.
A new advanced computing technique used in the Pentium is called branch prediction. Using branch prediction, the Pentium makes an educated guess where the next instruction following a conditional instruction will be.
The Pentium has a 64-bit data bus. This means that it can perform data transfers with an external device (memory, for example) twice as fast as a processor with a 32-bit data bus.
The 8080 and the 8086 define the base programming model for the entire X86 family.
The newer members of the X86 family of advanced microprocessors have greater computing power because they are faster, they use 32-bit registers instead of 16-bit registers used in earlier advanced microprocessors (8088, 8086, 80286).
Once you understand the basic programming model for the 8088 and 8086 processors, you will be able to understand the improvements made with the newer models.
The base programming model of the 16-bit (8088, 8086 and 286) and 32-bit (386 and 486) processors is very much the same. The difference is in register length, extra data segment registers, and added features.
The base programming model is made up of three register group.
The first set contains eight general purpose registers called the A, B, C, D, SI (source index), DI (destination index), SP (stack pointer) and BP (base pointer) register. Depending on the specific processor, these are either 16- or 32-bit registers.
When the microprocessor uses 32-bit registers, the eight general-purpose registers are called the EAX, EBX, ECX, EDX, ESI, EDI, ESP, and EBP registers. The E tells us that these registers have extended length.
The ALU works with these register to give the X86 microprocessors their computation and data movement capability.
The second set of registers are the segment registers. This set of register consists of the code segment (CS) and stack segment (SS) registers, and either two (286) or four data segment register (80386). The data segment registers are called DS, ES, FS, and GS.
The X86 registers manage operations with external memory. Address computation and data movement are performed here. A second ALU is dedicated to processing memory address data which works with the segment registers.
These pre-fetched instructions are immediately available for processing once the current instruction is complete; therefore, when executing this software, the processor does not wait for a fetch cycle. Prefetching can significantly speed up execution time.
This process may not work for every instruction because software does not always execute one instruction after the other. For example, branching may cause the next instruction to come from a very different location in memory.
The most advanced members of the X86 family have special logic which analyzes the prefetched instructions and attempts to anticipate branching and other such changes so that the correct instructions are prefetched.
The more advanced X86 processors also store frequently used data in memory which is on board the processor. Again, having this data right at hand, in a data cache, avoids the need for an external memory access cycle and therefore speeds up processing time.