Microprocessor Logic – how a microprocessor works

July 7, 2009 at 12:00 am 3 comments

Microprocessor Logic


Photo courtesy
Intel Corporation
Intel Pentium 4 processor

To understand how a microprocessor works, it is helpful to look inside and learn about the logic used to create one. In the process you can also learn about assembly language — the native language of a microprocessor — and many of the things that engineers can do to boost the speed of a processor.

A microprocessor executes a collection of machine instructions that tell the processor what to do. Based on the instructions, a microprocessor does three basic things:

  • Using its ALU (Arithmetic/Logic Unit), a microprocessor can perform mathematical operations like addition, subtraction, multiplication and division. Modern microprocessors contain complete floating point processors that can perform extremely sophisticated operations on large floating point numbers.
  • A microprocessor can move data from one memory location to another.
  • A microprocessor can make decisions and jump to a new set of instructions based on those decisions.

There may be very sophisticated things that a microprocessor does, but those are its three basic activities. The following diagram shows an extremely simple microprocessor capable of doing those three things:

This is about as simple as a microprocessor gets. This microprocessor has:

  • An address bus (that may be 8, 16 or 32 bits wide) that sends an address to memory
  • A data bus (that may be 8, 16 or 32 bits wide) that can send data to memory or receive data from memory
  • An RD (read) and WR (write) line to tell the memory whether it wants to set or get the addressed location
  • A clock line that lets a clock pulse sequence the processor
  • A reset line that resets the program counter to zero (or whatever) and restarts execution

Lets assume that both the address and data buses are 8 bits wide in this example.

Here are the components of this simple microprocessor:

  • Registers A, B and C are simply latches made out of flip-flops. (See the section on “edge-triggered latches” in How Boolean Logic Works for details.)
  • The address latch is just like registers A, B and C.
  • The program counter is a latch with the extra ability to increment by 1 when told to do so, and also to reset to zero when told to do so.
  • The ALU could be as simple as an 8-bit adder (see the section on adders in How Boolean Logic Works for details), or it might be able to add, subtract, multiply and divide 8-bit values. Lets assume the latter here.
  • The test register is a special latch that can hold values from comparisons performed in the ALU. An ALU can normally compare two numbers and determine if they are equal, if one is greater than the other, etc. The test register can also normally hold a carry bit from the last stage of the adder. It stores these values in flip-flops and then the instruction decoder can use the values to make decisions.
  • There are six boxes marked “3-State” in the diagram. These are tri-state buffers. A tri-state buffer can pass a 1, a 0 or it can essentially disconnect its output (imagine a switch that totally disconnects the output line from the wire that the output is heading toward). A tri-state buffer allows multiple outputs to connect to a wire, but only one of them to actually drive a 1 or a 0 onto the line.
  • The instruction register and instruction decoder are responsible for controlling all of the other components.

Although they are not shown in this diagram, there would be control lines from the instruction decoder that would:

  • Tell the A register to latch the value currently on the data bus
  • Tell the B register to latch the value currently on the data bus
  • Tell the C register to latch the value currently output by the ALU
  • Tell the program counter register to latch the value currently on the data bus
  • Tell the address register to latch the value currently on the data bus
  • Tell the instruction register to latch the value currently on the data bus
  • Tell the program counter to increment
  • Tell the program counter to reset to zero
  • Activate any of the six tri-state buffers (six separate lines)
  • Tell the ALU what operation to perform
  • Tell the test register to latch the ALUs test bits
  • Activate the RD line
  • Activate the WR line

Coming into the instruction decoder are the bits from the test register and the clock line, as well as the bits from the instruction register.

 
source// http://computer.howstuffworks.com/microprocessor2.htm

Entry filed under: Motherboards. Tags: .

A-301 High Voltage Amplifier/ Piezo Driver and Modulator2

3 Comments Add your own

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Trackback this post  |  Subscribe to the comments via RSS Feed


Stats

  • 41,020 hits

من محتويات الموقع

كثرت إصدارات الماسنجر وتبعثرت بتشاتها وبرامجها .. فالبعض يبحث عن جديد الماسنجر .. والبحض يبحث عن ماسنجر 7.5 .. ماسنجر هوتميل والبعض يبحث عن ماسنجر 7 نحن نوجهك إلى تحميل برنامج ماسنجر بلس مسنجر 9 برنامج الماسنجر الجديد هوتميل تسعة ... برنامج ماسنجر هوتميل بلس لاصدار ماسنجر لايف 9 ماسنجر,ماسنجر بلص,تحميل الماسنجر,ماسنجر 8,صور ماسنجر,اصدارات الماسنجر و ما قبله من اصدارات.. تحميل مسنجر مسنجر بلس مسنجر 9 مسنجر ياهو مسنجر لايف تنزيل مسنجر messenger اقلاع سوفت messenger + msn + hotmail download msn messenger hotmail msn web messenger hotmail msn messenger without hotmail msn messenger und hotmail telecharger msn messenger hotmail msn hotmail messenger mac Internet turbo 2009 ,جديد البرامج و الإنترنات ,1waw.com ,Download parameg FOR MOBILE TORRENT ,كشف الملفات التالفه في الويندوز ,فضل برنامج للصور المتحركة عربي ,فتح محطات ART الفضائية ,Firefox ,برامج تشغيل الملفات ,تحميل أقوى مشغل ملفات flv ,تحميل برنامج مجانا internet download manager ,Fotos+do+sound+forge ,NLite ,كول اديت ,Free arc لفك الضغط ,تنزيل ساعة على سطح مكتب الكمبيوتر ,برنامج تحويل الفيديو يوتيوب الى 3gp ,تنزيل برنامج لفتح الاناشيد ,Fotos+do+sound+forge ,برامج كمبيوتر للفيروسات ,Six free mp3 ,تحويل pdf الي word ,نوع الفيديو للبرو جولد ,تحميل برنامج Passware Kit Enterprise ليش نسخة Demo ,Ares+tube ,Image banner maker ,Kmp 2007 ,تنزيل برنامج لتشغيل اناشيد mp3 ,برنامج مشاهدة القنوات الفضائية ,موقع تحميل الانتي فايروس 2010 ,تنزيل المتصفحات الجديدة ,Download free Revo Uninstaller 2.1.5.0 ,تشغيل كاميرا nokia pc suite ,Zib password remova l برنامج ,تحميل برامج تشغيل الفيديو ,تحميل برنامج عن طريق الجوال لمشاهده التلفزيون ,افلام يوتيوب للهاتف المحمول مجانا ,تسريع الانترنت ,Ares+tube ,برامج حماية من الفيروسات مجانية ,Antivir free download ,برامج نت ,كيفية التعامل مع الملفات المضغوطة ,كول اديت ,Kis 9.0.0.459 key ,برنامج الالة الحاسبة ,برنامج تغيير الأصوات للكمبيوتر من برامج نت ,برامج مشغلات الفيدبو كمبيوتر ,برنامج youtube لنوكيا 73

%d bloggers like this: