What do you understand by scan codes, Computer Engineering

Assignment Help:

Q. What do you understand by Scan Codes?

A scan code is a code produced by a microprocessor in keyboard when a key is pressed and is unique to key struck. When this code is received by computer it reports an interrupt and looks up scan code table in BIOS and realize which keys have been pressed and in what combination. Special memory locations known as status bytes tell the status of locking and toggle keys for example Caps lock etc. Every key press produces two different scan codes - one on key-push down known as Make code and another on its popping back known as Break code. This two-key scheme enables the computer to tell when a key is held pressed down for example ALT key when pressing another key say CTRL-ALT-DEL.


Related Discussions:- What do you understand by scan codes

Address - operand data types, Q. Address - operand data types? A...

Q. Address - operand data types? Addresses : Operands residing in memory are specified by their memory address while operands residing in registers are specified by a re

Illustrate about first generation computers, Q. Illustrate about First Gene...

Q. Illustrate about First Generation Computers? It is certainly ironic that scientific inventions of great impact have frequently been linked with supporting a very sad as well

Define the difference between union and structure, Define the difference be...

Define the difference between union and structure The main difference between union and structure is the storage allocation. In Union , for each variable the compiler allocates

User compatibility & appropriateness of inputs and outputs, User Compatibil...

User Compatibility & Appropriateness of Inputs and Outputs User compatibility - this is the degree to which the machine works towards task completion in way that suits the u

When web pages containing emails are sent out, When web pages containing em...

When web pages containing emails are sent out they are prefixed by MIME Header. Why? Primarily email consisted messages having simple text written into English and expressed in

What is branch prediction logic, What is Branch prediction logic Bran...

What is Branch prediction logic Branch prediction logic in Pentium: Pentium microprocessor uses branch prediction logic to decrease the time needed for a branch caused by in

Demux., Implement the full substractor using 8:1demux

Implement the full substractor using 8:1demux

Explain the daa instruction, Explain the DAA DAA instruction follows th...

Explain the DAA DAA instruction follows the ADC or ADD instruction to adjust the result into a BCD result. DAA instruction functions only with the AL register, this addition sh

Megaflops, Speed in scientific computing is measured in megaflops, gigaflop...

Speed in scientific computing is measured in megaflops, gigaflops, teraflops and petaflops. A megaflop is 10 6 floating point arithmetic operations (+, -, *, /) in one second What

What is sgml, SGML is very large, influential, and difficult. It has been i...

SGML is very large, influential, and difficult. It has been in important industrial and commercial use for nearly two decades, and there is a important body of expertise and softwa

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd