character - Who Teaches the CPU 'A..B..C'? -



character - Who Teaches the CPU 'A..B..C'? -

excuse idiotic question, can't seem find 1 satisfying reply internet. mean can see character 'x' displayed on screen right pc's start screen. how computer know bit patterns translated 'x'? gives such definitions? bios, os, cpu or display driver or apps?

it depends @ moment, , operating system, , on hardware. linux on current x86 pc desktop:

at boot time, uses vga driver (and bios has limited display functions). iirc, original vga cards had rom containing fixed width font, , still used (in compatibility mode).

iirc, graphics cards have rom bios , initial vga font. used @ bios time or during boot process.

but of time, linux desktop uses x11 server xorg. server manages fonts, , display them using graphics video card (which has gpu), copying appropriate bitmaps. x11 protocol knows fonts, today applications utilize client side xft.

the future wayland architecture have fonts on client side.

you might on osdev, has several related pages.

low-level graphics libraries libsdl or opengl (or xlib) have functions draw text in arbitrary font, e.g. xdrawtext originally, or xftdrawstring xft.

high-level graphical user interface toolkits qt or gtk provide widgets text display, around event loop.

in gory details, things complex , hardware specific (and sadly, graphics cards manufacturers -e.g. nvidia- don't publish specification of hardware - needs reverse engineered). why utilize operating scheme provide abstraction code on.

character ascii utf

Comments

Post a Comment

Popular posts from this blog

c# - ASP.NET MVC Sequence contains no matching element -

c# - ASP.NET MVC Sequence contains no matching element - i new asp.net mvc. have finished project unusual issue appeared in project. as seek run project error message. an exception of type 'system.invalidoperationexception' occurred in entityframework.dll not handled in user code additional information: sequence contains no matching element in 1 of controller using statement below groups display in dropdownlist. http://localhost....../clients (trying run page) , getting error on line containing code below. viewbag.groupdropdownvalues = new selectlist(db.groups.orderby(m => m.groupid), "groupid", "groupname"); or other controller: viewbag.categorydropdownvalues = new selectlist(db.category.orderby(m => m.categoryid), "categoryid", "categoryname"); this happening in controllers using syntax. i need display dropdownlists values database. working correctly till morning. don't have thought changed ,
Read more

java - Parsing XML, skip certain tags -

java - Parsing XML, skip certain tags - i next mkyong's great tutorial on how parse xml in java, have situation need read tags within area. e.g. <?xml version="1.0"?> <company> <staff id="1001"> <firstname>yong</firstname> <lastname>mook kim</lastname> <nickname>mkyong</nickname> <salary>100000</salary> </staff> <staff id="2001"> <firstname>low</firstname> <lastname>yin fong</lastname> <nickname>fong fong</nickname> <salary>200000</salary> </staff> <changes> <staff id="2001"> <firstname>low</firstname> <lastname>yin fong</lastname> <nickname>fong fong</nickname> <old_salary>175000</salary> <ne
Read more

rest - How to invalidate user session on inactivity in a stateless server? -

rest - How to invalidate user session on inactivity in a stateless server? - i'm building stateless restful server backend in java, used angularjs frontend. since should stateless, don't create sessions generate access tokens, more exactly json web tokens, client has nowadays on every request. the tokens contain "expires" field acts absolute expiration date. however, have additional expiration on user inactivity. define access token valid long 24 hours if user active 1 time every 30 minutes. i implement writing database on every request , verify time between requests, seems lot of work working out of box when using application server's session management. to 100% stateless on server side need force state logic client. solution is: issue jwt 2 expiry dates (one session - 30 minutes, sec refresh - 24h) implement getting new token same user previous token (new token has new expiry date session, same refresh) reject requests when whatever expir
Read more