How to get keyboard input in assmebly

[motosftos]

Please help me i want to get keyboard input in assembly.

example: if user types "help" and enter it should show help. I want code ina ssembly language please!!??!?!?!?!

Thanks in advance.

[nullplan]

You are missing so many abstractions.

First, the input driver. What keyboard do you want to support, the good old PS/2 keyboard or USB? For the latter, you need USB support. And good luck with that.

For the former, you need to program the PS/2 controller. It will give you an interrupt once a key is pressed. Then you read out the code from the keyboard controller and save that in a buffer somewhere. How that is read out is up to your system design.

Then, the terminal driver. If the "echo" option is set, you should read the input and then write it out back to the terminal again, so that the user can see what they have typed,

Then the output driver, which needs to keep track of cursor position and maybe render the characters.

And finally, the application that actually consumes the input and does something with it.

[iansjack]

You do it the same way in assembler as you would in C. It's just more difficult because higher-level languages make things easier.

No insult intended but, from your posts so far, you just aren't ready for OS programming. Asking others to do the programming for you isn't going to help.

[Schol-R-LEA]

@motosftos: Have you read the sticky post Links and advice for new members yet? It gives a fair amount of advice on OS Dev, and links to several relevant pages in the wiki - pages which, based on this post, you don't seem to have read yet.

The pages How To Ask Questions and Beginner Mistakes seem particularly relevant, as does the developer archetype/anti-pattern page Duct von Tape.

To sum up, we are ready to help you, but you need to be ready to receive that help first. Asking for other people to write your code for you definitely doesn't count. What does count? Having enough experience and understanding, and the drive to gain more, before you even consider a project of this scale. I won't say you'll never be able to write an operating system, but it doesn't sound like you are ready now.

[motosftos]

Figured the code:

Code: Select all

get_string:
   xor cl, cl
 
 .loop:
   mov ah, 0
   int 0x16   ; wait for keypress
 
   cmp al, 0x08    ; backspace pressed?
   je .backspace   ; yes, handle it
 
   cmp al, 0x0D  ; enter pressed?
   je .done      ; yes, we're done
 
   cmp cl, 0x3F  ; 63 chars inputted?
   je .loop      ; yes, only let in backspace and enter
   mov ah, 0x0E
   int 0x10      ; print out character
 
   stosb  ; put character in buffer
   inc cl
   jmp .loop
 
 .backspace:
   cmp cl, 0	; beginning of string?
   je .loop	; yes, ignore the key
 
   dec di
   mov byte [di], 0	; delete character
   dec cl		; decrement counter as well
 
   mov ah, 0x0E
   mov al, 0x08
   int 10h		; backspace on the screen
 
   mov al, ' '
   int 10h		; blank character out
 
   mov al, 0x08
   int 10h		; backspace again
 
   jmp .loop	; go to the main loop
 
 .done:
   mov al, 0	; null terminator
   stosb
 
   mov ah, 0x0E
   mov al, 0x0D
   int 0x10
   mov al, 0x0A
   int 0x10		; newline
 
   ret

Thanks for all of your help.

Thank you WikiOSdev Forum.

[iansjack]

You've figured out how to get keyboard input in real mode.