The Intel microprocessor is a variant of the Intel Introduced on July 1, , the . x86 architecture · Motorola · Maximum mode · Minimum mode · iAPX for the iAPX designation; Professional Graphics Controller · Transistor  Co-processor‎: ‎Intel and Microprocessors. • announced in ; is a 16 bit microprocessor with a 16 bit data bus. • announced in ; is a 16 bit. / ARCHITECTURE HISTORY OF THE INTEL MICROPROCESSORS F The 4-bit Microprocessors Intel F The bit Microprocessors.


Author: Novella Ullrich IV
Country: France
Language: English
Genre: Education
Published: 23 May 2017
Pages: 209
PDF File Size: 39.1 Mb
ePub File Size: 10.18 Mb
ISBN: 490-4-65668-771-5
Downloads: 47386
Price: Free
Uploader: Novella Ullrich IV


Cutting down the 8088 architecture to eight bits made it a serious bottleneck in the When the queue is empty, instructions take as long to complete as they take to fetch.

Both the and take four clock cycles to complete a bus cycle; whereas for the this means four clocks to transfer two bytes, on the 8088 architecture is four clocks per 8088 architecture. Therefore, for example, a two-byte shift or rotate instruction, which takes the EU only two clock cycles to execute, actually takes eight clock cycles to complete if it is not in the prefetch queue.

Intel 8088

In short, an typically runs about half as fast as clocked at the same rate, because of the bus bottleneck the only major 8088 architecture.

A side effect of the design, with the slow bus and the small prefetch queue, is that the speed of code execution can be very dependent on instruction order. When programming thefor CPU efficiency, it is vital to interleave long-running instructions with short ones whenever possible. For example, a repeated string operation or a shift by three or more will take long enough to allow time for the 4-byte prefetch queue to completely fill.

Explain the architecture of microprocessor.

If short instructions i. If, on the other hand, the slow instructions are executed sequentially, back to back, then after 8088 architecture first of them the bus unit will be forced to idle because the queue will already be full, with the consequence that later more 8088 architecture the faster instructions will suffer fetch delays that might have been avoidable.

As some instructions, such as single-bit-position shifts and rotates, take literally 4 times as long to fetch as to execute, [c] the overall effect can be a slowdown by a factor of two or more.

If those code segments are the bodies of loops, the difference in execution time may be very noticeable on the human timescale. The is also like the slow at accessing memory.


The same ALU that is used to execute arithmetic and logic instructions is also used to calculate effective addresses. There is a separate 8088 architecture for adding a shifted segment register to the offset address, 8088 architecture the offset EA itself is always calculated entirely in the main ALU.

Furthermore, the loose 8088 architecture of the EU and BIU bus unit inserts 8088 architecture overhead between the units, and the four-clock period bus transfer cycle is not particularly streamlined. Contrast this with the two-clock period bus cycle of the CPU and the 's three-clock period bus cycle with pipelining down to two cycles for most transfers.

  • Intel - Wikipedia
  • General Registers

8088 architecture Most instructions that can operate on either registers or memory, including common ALU and 8088 architecture operations, are at least four times slower for memory operands than for only register operands.

Therefore, efficient and programs avoid repeated access of memory operands when possible, loading operands from memory into registers to work with them there and storing back only the finished results.

Introduction to Microprocessors

The relatively large general register set of the compared to its contemporaries assists this strategy. When there are not enough registers for all variables that are needed at once, saving registers by pushing them onto the stack and popping them 8088 architecture to restore them is the fastest way to use memory to augment the registers, as the stack PUSH and POP instructions are the fastest memory operations.

Are four of the address lines just ignored since we can only send 16 bits of information from our addressing registers?

Next time your Windows operating system throws up an error, look to see if it gives you the address where the error occurred.

The Intel 8088 Architecture

If it does, you should see a number that looks something like: A34E 8088 architecture number is actually the combination of 2 registers: Note that a four digit hexadecimal number results in a 16 bit binary number.

It is the combination of these two bit 8088 architecture that creates the bit address line.


To do this, take the value in the segment register and shift if left four places, i. This value is then added to the pointer or index register. This makes the value from our example: Therefore, the process of trying to access a single location in 8088 architecture processor's memory space takes three things: If we look at this from the memory space point of view, the segment register shifted left four places so that four zeros are filled in from the right points to an address somewhere in the memory space.

There are two purposes for this summation of segment and pointer registers to access a single, physical 8088 architecture address.

Related Post