Hello,
I'm beginning in the OS development(In Assembly, Nasm as Assembler) and i need to implement a command-line on it, but i don't know how to do this, but what i want to say as command-line is like MS-DOS or UNIX:

> ver
BerlOS v.0.0.1
> _

But i don't know how to do the input method(ver in the command). In the repetition of the > before the user input things i know, i only need to do a JMP to the section that prints the > and the input method, if it's needed, here is my code:

[BITS 16]	     ; 16 bit code generation
[ORG 0x7C00]	 ; ORGin location is 7C00

JMP short main   ; Jump past disk description section
NOP              ; Pad out before disk description

; ------------------------------------------------------------------
; Disk description table, to make it a valid floppy
; Note: some of these values are hard-coded in the source!
; Values are those used by IBM for 1.44 MB, 3.5" diskette

OEMLabel            db "BERL OS"    ; Disk label - 8 chars
BytesPerSector      dw 512          ; Bytes per sector
SectorsPerCluster   db 1            ; Sectors per cluster
ReservedForBoot     dw 1            ; Reserved sectors for boot record
NumberOfFats        db 2            ; Number of copies of the FAT
RootDirEntries      dw 224          ; Number of entries in root dir
LogicalSectors      dw 2880         ; Number of logical sectors
MediumByte          db 0F0h         ; Medium descriptor byte
SectorsPerFat       dw 9            ; Sectors per FAT
SectorsPerTrack     dw 18           ; Sectors per track (36/cylinder)
Sides               dw 2            ; Number of sides/heads
HiddenSectors       dd 0            ; Number of hidden sectors
LargeSectors        dd 0            ; Number of LBA sectors
DriveNo             dw 0            ; Drive No: 0
Signature           db 41           ; Drive signature: 41 for floppy
VolumeID            dd 00000000h    ; Volume ID: any number
VolumeLabel         db "BERL OS"    ; Volume Label: any 11 chars
FileSystem          db "FAT12"      ; File system type: don't change!

; End of the disk description table
; ------------------------------------------------------------------

main:
MOV BX, 0                           ; Disable blinking.
MOV BH, 00h
MOV BL, 07h                         ; Color settings
MOV AL, 1
MOV BH, 0
MOV BL, 02h
MOV CX, osmsgend - os_msg           ; Calculate message size. 
MOV DL, 30
MOV DH, 0
PUSH CS
POP ES
MOV BP, os_msg
MOV AH, 13h
INT 10h
JMP wel

wel:
MOV BH, 00h
MOV BL, 07h
MOV AL, 1
MOV BH, 0
MOV BL, 059 
MOV CX, welcome_end - welcome       ; Calculate message size. 
MOV DL, 32
MOV DH, 2
PUSH CS
POP ES
MOV BP, welcome
MOV AH, 13h
INT 10h
JMP osmsgend
                         
welcome DB "Welcome !"
welcome_end:
                         
os_msg DB "BerlOS v0.0.1"
osmsgend:
JMP $

; Boot things
TIMES 510-($-$$) DB 0	            ; Fill the rest of the sector with zeros
DW 0xAA55		                    ; Boot signature

The only thing that i need too know how to do is the input characters method.

Thanks,
Nathan Paulino Campos

You're using the 0x10 VIDEO BIOS services handler for your video handling so use the 0x16 KEYBOARD BIOS services handler for your keyboard handling!

; Get Keyboard value (and wait for press)
  mov ah,0
  int 16h   ; KEYBOARD
      ;ah=scan code   al=ASCII character

Hello wildgoose,
Thanks for your help, now i know that INT 16h is for keyboard, but if i want to improve like, the user types: ver , then when he press enter the OS shows a message, like: ver DB "ver. 0.0.1" .

Thanks,
Nathan Paulino Campos

After data entry, remove carriage return and set a terminator!

Create a master list of commands! A table lookup of string addresses and scan through the list one at a time and do a caseless string to data entered. When you find a caseless match you have your command. Then jump to the code to handle that command!

You could use a structure table that contains the pointer to the string, and address of the function.


Initially just write a string compare function and do a series of if-then's to find your matching string!

But how i can do this?
Sorry about this simple questions, but i'm learning Assembly for OS's.

Thanks for you attention!

One step at a time

xVer  db   'Ver',0
Key   db    dup(128)
Kscan  db    dup(128)


  xor bx,bx

KeyIn:
  mov ah,0
  int 16h   ; KEYBOARD
      ;ah=scan code   al=ASCII character

  mov Key[ bx ],al
   mov KScan[ bx ],ah
   inc bx
   cmp al,0dh     ; Carriage return
   jne  KeyIn

      ; bx = buffer Length
   mov Key[ bx - 1 ],0           ; Overwrite with terminator

      ; String now in buffer

Visually inspect buffer to make sure the string is there intact!

Then work on a string compare function

mov ax,offset KeyBuf
   mov dx,offset xVer
   call StrICmp
   jnc  next

   ;;; Have a match!
   jmp done

next:

done:

Ok, i'm going to try, any thing i will post, but i know that i will not have problems, thanks!

If it's needed, here is the code:

[BITS 16]	     ; 16 bit code generation
[ORG 0x7C00]	 ; ORGin location is 7C00

JMP short main   ; Jump past disk description section
NOP              ; Pad out before disk description

; ------------------------------------------------------------------
; Disk description table, to make it a valid floppy
; Note: some of these values are hard-coded in the source!
; Values are those used by IBM for 1.44 MB, 3.5" diskette

OEMLabel            db "BERL OS"    ; Disk label - 8 chars
BytesPerSector      dw 512          ; Bytes per sector
SectorsPerCluster   db 1            ; Sectors per cluster
ReservedForBoot     dw 1            ; Reserved sectors for boot record
NumberOfFats        db 2            ; Number of copies of the FAT
RootDirEntries      dw 224          ; Number of entries in root dir
LogicalSectors      dw 2880         ; Number of logical sectors
MediumByte          db 0F0h         ; Medium descriptor byte
SectorsPerFat       dw 9            ; Sectors per FAT
SectorsPerTrack     dw 18           ; Sectors per track (36/cylinder)
Sides               dw 2            ; Number of sides/heads
HiddenSectors       dd 0            ; Number of hidden sectors
LargeSectors        dd 0            ; Number of LBA sectors
DriveNo             dw 0            ; Drive No: 0
Signature           db 41           ; Drive signature: 41 for floppy
VolumeID            dd 00000000h    ; Volume ID: any number
VolumeLabel         db "BERL OS"    ; Volume Label: any 11 chars
FileSystem          db "FAT12"      ; File system type: don't change!

; End of the disk description table
; ------------------------------------------------------------------

main:
MOV BX, 0                           ; Disable blinking.
MOV BH, 00h
MOV BL, 07h                         ; Color settings
MOV AL, 1
MOV BH, 0
MOV BL, 02h
MOV CX, osmsgend - os_msg           ; Calculate message size. 
MOV DL, 30
MOV DH, 0
PUSH CS
POP ES
MOV BP, os_msg
MOV AH, 13h
INT 10h
JMP wel

wel:
MOV BH, 00h
MOV BL, 07h
MOV AL, 1
MOV BH, 0
MOV BL, 059 
MOV CX, welcome_end - welcome       ; Calculate message size. 
MOV DL, 32
MOV DH, 2
PUSH CS
POP ES
MOV BP, welcome
MOV AH, 13h
INT 10h
JMP KeyIn

; ------------------------------------------
; Keyboard input method
xVer  db   'Ver', 0
Key   db    dup(128)
Kscan  db    dup(128)


  xor bx,bx

KeyIn:
  mov ah,0
  int 16h   ; KEYBOARD
      ;ah=scan code   al=ASCII character

  mov Key[ bx ],al
   mov KScan[ bx ],ah
   inc bx
   cmp al,0dh     ; Carriage return
   jne  KeyIn

      ; bx = buffer Length
   mov Key[ bx - 1 ],0           ; Overwrite with terminator

      ; String now in buffer
   mov ax,offset KeyBuf
   mov dx,offset xVer
   call StrICmp
JMP osmsgend

; End of input characters method
; ------------------------------------------

                         
welcome DB "Welcome !"
welcome_end:
                         
os_msg DB "BerlOS v0.0.1"
osmsgend:
JMP $

; Boot things
TIMES 510-($-$$) DB 0	            ; Fill the rest of the sector with zeros
DW 0xAA55		                    ; Boot signature

Thanks!

Look at the line number that contains the error and look for things.


Line#35
You may need the label on the same line as instruction. Some assemblers require this, some don't!

main: MOV BX, 0 ; Disable blinking.

Line#70 and #71
;Key db dup(128)
;Kscan db dup(128)
Key db 128 dup(?)
Kscan db 128 dup(?)

Line#81,82 should then be fixed.

Line#88 mov byte ptr Key[ bx - 1 ],0 ; Overwrite with
terminator

Wrong label name
mov ax,offset Key

Don't know about 92
mov dx,offset xVer

Thanks, but i'm getting the same errors, when i try to compile with all the fixes, remember that i'm using Nasm as compiler.

Here is the log of the compiler:

C:\Users\Nathan\Desktop>nasm os.asm
os.asm:70: error: comma expected after operand 1
os.asm:71: error: comma expected after operand 1
os.asm:81: error: comma, colon or end of line expected
os.asm:82: error: comma, colon or end of line expected
os.asm:88: error: comma, colon or end of line expected
os.asm:91: error: comma, colon or end of line expected
os.asm:92: error: comma, colon or end of line expected

What is wrong?

And here is the code modified:

[BITS 16]	     ; 16 bit code generation
[ORG 0x7C00]	 ; ORGin location is 7C00

JMP short main   ; Jump past disk description section
NOP              ; Pad out before disk description

; ------------------------------------------------------------------
; Disk description table, to make it a valid floppy
; Note: some of these values are hard-coded in the source!
; Values are those used by IBM for 1.44 MB, 3.5" diskette

OEMLabel            db "BERL OS"    ; Disk label - 8 chars
BytesPerSector      dw 512          ; Bytes per sector
SectorsPerCluster   db 1            ; Sectors per cluster
ReservedForBoot     dw 1            ; Reserved sectors for boot record
NumberOfFats        db 2            ; Number of copies of the FAT
RootDirEntries      dw 224          ; Number of entries in root dir
LogicalSectors      dw 2880         ; Number of logical sectors
MediumByte          db 0F0h         ; Medium descriptor byte
SectorsPerFat       dw 9            ; Sectors per FAT
SectorsPerTrack     dw 18           ; Sectors per track (36/cylinder)
Sides               dw 2            ; Number of sides/heads
HiddenSectors       dd 0            ; Number of hidden sectors
LargeSectors        dd 0            ; Number of LBA sectors
DriveNo             dw 0            ; Drive No: 0
Signature           db 41           ; Drive signature: 41 for floppy
VolumeID            dd 00000000h    ; Volume ID: any number
VolumeLabel         db "BERL OS"    ; Volume Label: any 11 chars
FileSystem          db "FAT12"      ; File system type: don't change!

; End of the disk description table
; ------------------------------------------------------------------

main:
MOV BX, 0                           ; Disable blinking.
MOV BH, 00h
MOV BL, 07h                         ; Color settings
MOV AL, 1
MOV BH, 0
MOV BL, 02h
MOV CX, osmsgend - os_msg           ; Calculate message size. 
MOV DL, 30
MOV DH, 0
PUSH CS
POP ES
MOV BP, os_msg
MOV AH, 13h
INT 10h
JMP wel

wel:
MOV BH, 00h
MOV BL, 07h
MOV AL, 1
MOV BH, 0
MOV BL, 059 
MOV CX, welcome_end - welcome       ; Calculate message size. 
MOV DL, 32
MOV DH, 2
PUSH CS
POP ES
MOV BP, welcome
MOV AH, 13h
INT 10h
JMP KeyIn

; ------------------------------------------
; Keyboard input method
xVer  db   'Ver', 0
Key   db  128  dup(?)
Kscan db  128  dup(?)


  xor bx,bx

KeyIn:
  mov ah,0
  int 16h   ; KEYBOARD
	  ;ah=scan code   al=ASCII character

  mov Key[ bx ],al
   mov KScan[ bx ],ah
   inc bx
   cmp al,0dh     ; Carriage return
   jne  KeyIn

	  ; bx = buffer Length
   mov byte ptr Key[ bx - 1 ], 0           ; Overwrite with terminator

	  ; String now in buffer
   mov ax,offset KeyBuf
   mov dx,offset xVer
   call StrICmp
JMP osmsgend

; End of input characters method
; ------------------------------------------


welcome DB "Welcome !"
welcome_end:

os_msg DB "BerlOS v0.0.1"
osmsgend:
JMP $

; Boot things
TIMES 510-($-$$) DB 0	            ; Fill the rest of the sector with zeros
DW 0xAA55		                    ; Boot signature

I definitely don't like NASM!
It has its own way of doing things....

; ------------------------------------------
; Keyboard input method
xVer:  db   'Ver',0

Key:  	times	128 db 0		; reserve 128 byte Keyboard
KScan:	times   128 db 0		; reserve 128 byte scan

;	______________
;	Keyboard Input

KeyIn:
	xor bx,bx

KeyIn0:
	mov ah,0
	int 16h				; KEYBOARD
      ;ah=scan code   al=ASCII character

	mov [Key+bx],al
	mov [KScan+bx],ah
	inc bx
	cmp al,0dh     ; Carriage return
	jne  KeyIn0

      ; bx = buffer Length
	mov word [Key + bx - 1],0           ; Overwrite with terminator

	; String now in buffer
	mov ax,Key
	mov dx,xVer

	call StrICmp

	JMP osmsgend



; End of input characters method
; ------------------------------------------


StrICmp
	stc
	ret

Thanks very much wildgoose!
You are a very nice and (the word that say that the person helps many people, because i don't know, remember that i live in Brazil).

God bless you my friend!

That terminator should have been someting like...

mov byte [Key + bx - 1],0           ; Overwrite with terminator

It's an 8-bit terminator not 16-bit.

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