standards - Hardware Devices and Standardization -


i'm not sure if each hardware type (display screen, usb, printer, etc) has follow unified standard in order communicate cpu. example, bits transmitted , forth between display screen interface , cpu interpreted cpu specific command, , interpretation correct (for same bits) if display screen used (from manufacturer).

if not true, how bios supposed communicate hundreds of different hardware devices varying methods of interpreting bits going , forth device interface cpu?

i find standardization notion more practical.

the bios needs understand limited set of hardware required boot cpu. not need understand "hundreds" of devices. example, bios has no idea usb printer is.

in general, bios understands following devices:

  • the cpu/chipset "core" hardware - e.g. ddr3 memory controller
  • basic pci/pci express initialization - nothing device-specific
  • the video controller - enough code basic initialization, typically provided option rom
  • the sata controller - long ide/achi compatible.
  • the usb controller - possibly usb 2.0
  • standard usb storage devices
  • standard usb keyboard/mouse devices
  • ethernet controller - typically provided option rom

any other device ignored bios, unless vendor included option rom on board. (you typically see on sas/scsi controllers or ethernet cards.)

note of devices listed above conform standard specification, software compatible regardless of made it. example, usb 2.0 controller should comply ehci spec, compatible across bioses. sata controllers should follow ahci spec.

once operating system loads, takes on bios , loads own drivers interface hardware.


Comments

Post a Comment

Popular posts from this blog

apache - Remove .php and add trailing slash in url using htaccess not loading css -

i have add following code htaccess file removing .php extension , add trailing slash urls. worked fine reduced page loading speed , css code not loading @ all. pages ugly. please help rewriteengine on rewritebase / ## hide .php extension snippet # externally redirect /dir/foo.php /dir/foo rewritecond %{the_request} ^[a-z]{3,}\s([^.]+)\.php [nc] rewriterule ^ %1/ [r,l] # add trailing slash rewritecond %{request_filename} !-f rewritecond %{request_uri} !/$ rewriterule . %{request_uri}/ [l,r=301] # internally forward /dir/foo /dir/foo.php rewritecond %{request_filename} !-d rewritecond %{request_filename}.php -f rewriterule ^(.*?)/?$ $1.php [l] we can rewrite urls using .htaccess files. before writing in .htaccess files need verify kind of server using. can check server adding a <?php phpinfo(); ?> in php page. ensure mod_rewrite module enabled in apache server. can identified checking phpinfo included page. common methods used url rewriting follows ...
Read more

javascript - jQuery show full size image on click -

pretty self explanatory not workking . i want display full image when user click on image... yes know there tons of plugins but i want keep simple. any idea ? css : .full { display: none; width: 500px; height: 500px; margin-left: 100px; margin-top: -300px; position: fixed; background-color: #f00; z-index: 6; } .thumbnail { width: 50px; height: 50px; } html: <img class="thumbnail" src="http://4.bp.blogspot.com/-uhbdp2esxng/txneptvi92i/aaaaaaaaaky/upfqis7zto0/s1600/rihanna-wallpaper.jpg"> jquery: $(document).ready(function() { $('.thumbnail').on('click', function() { var img = $('<img />',{src:this.src,'class':'full'}); $('.full').html(img).show(); console.log('done!'); }); }); try looking how jquery works. $(document).ready(function() { $('.thumbnail').on('click', function(...
Read more