Programming Forums > Application Development > Assembly

kruptof · May 16th, 2006, 3:47 PM

can anybody tell me a good way to display numbers In ASM using dos interrupts, because the dos interrupt 21h sub routine 02 ouputs values in their ascii equivallent so how do i display a two figured result of an calculation, for example how do i display the number 10 because if i use the the does interrupt i said above it would convert it to its asci value which is ":" . Sorry if you have found my explaination confusing. I thank you for your replies in advance.

Narue · May 16th, 2006, 4:46 PM

It's a two step process. First you break the number down into individual digits (a simple modulus/division operation). Then you convert each digit into the ASCII representation (try adding 48 to the value). Print the resulting characters in the right order and you're sorted.

kruptof · May 16th, 2006, 4:54 PM

thanks Narue........i understand and know about the adding the 48 trick but i don't understand the moduls/division operation that you have mentioned. perhaps you can give a simple demonstation of that.

okay sorry Narue just took a moment to digest what you have suggested.......and know i understand what you were implying..........but know how do get the remainder of a division operation in ASM .......i am using A86 if that helps. Thanks for the help so far Narue

Narue · May 16th, 2006, 5:15 PM

>but know how do get the remainder of a division operation in ASM

(Toggle Plain Text)

mov dx,0   ; It's important to clear DX because DX:AX is the dividend
mov ax,123
mov bx,10  ; Divisor
div 10

After the div instruction, AX (the quotient) will contain 12 and DX (the remainder) will contain 3. This design is well suited for a loop where the least significant digit is chopped off of AX for each iteration.

kruptof · May 16th, 2006, 5:32 PM

thanks again Narue............but know how do i output these calculations i can't ouput this using sub routine 02 of 21h because whatever is being ouputted has to be stored in dl which is a byte and the calculations of above are in 2 bytes dx ( i think) so you can't do mov dl,dx, so how do know display these calculations.

I appreciate your support Narue.

I found a few errors in the code you have posted above, so i took the liberty to correct and post it for other users that browse through this thread:

Quote:

mov dx,0
mov ax,12
mov bx,10
div b

Narue · May 16th, 2006, 7:20 PM

>so how do know display these calculations
Save them in memory as a string, then use 09h of interrupt 21h to print the string.

kruptof · May 17th, 2006, 6:02 AM

what do i just choose a random memory location, and if i do wouldn't there be a possibilty that another program is using that memory location. Can you demonstate this Narue please.

Narue · May 17th, 2006, 8:26 PM

>what do i just choose a random memory location
Something like that. You declare enough space.

>Can you demonstate this Narue please.
Oh, very well. This is FASM though, I don't have A86:

(Toggle Plain Text)

format MZ

org	100h
jmp	start

save db 4 dup '$'

start:
	mov	ax,123
	mov	bx,10
	mov	di,2

    convert:
	mov	dx,0
	div	bx
	add	dx,'0'
	mov	[save+di],dl
	dec	di
	test	ax,ax
	jnz	convert

	; Display the result
	mov	ah,09h
	mov	dx,save
	int	21h

	; Finish up
	mov	ah,4Ch
	mov	al,0
	int	21h

kruptof · May 18th, 2006, 12:00 PM

wow thanks Narue.............but why did u put 2 in the di regester

DaWei · May 18th, 2006, 12:07 PM

Endianness.

May 16th, 2006, 3:47 PM	#1
kruptof Professional Programmer Join Date: May 2006 Location: UK - London Posts: 333 Rep Power: 3	Assembler displaying digits can anybody tell me a good way to display numbers In ASM using dos interrupts, because the dos interrupt 21h sub routine 02 ouputs values in their ascii equivallent so how do i display a two figured result of an calculation, for example how do i display the number 10 because if i use the the does interrupt i said above it would convert it to its asci value which is ":" . Sorry if you have found my explaination confusing. I thank you for your replies in advance.

May 16th, 2006, 4:46 PM	#2
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	It's a two step process. First you break the number down into individual digits (a simple modulus/division operation). Then you convert each digit into the ASCII representation (try adding 48 to the value). Print the resulting characters in the right order and you're sorted. __________________ Even if the voices aren't real, they have some pretty good ideas.

May 16th, 2006, 5:15 PM	#4
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>but know how do get the remainder of a division operation in ASM (Toggle Plain Text) mov dx,0 ; It's important to clear DX because DX:AX is the dividend mov ax,123 mov bx,10 ; Divisor div 10 mov dx,0 ; It's important to clear DX because DX:AX is the dividend mov ax,123 mov bx,10 ; Divisor div 10 After the div instruction, AX (the quotient) will contain 12 and DX (the remainder) will contain 3. This design is well suited for a loop where the least significant digit is chopped off of AX for each iteration. __________________ Even if the voices aren't real, they have some pretty good ideas.

May 16th, 2006, 7:20 PM	#6
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>so how do know display these calculations Save them in memory as a string, then use 09h of interrupt 21h to print the string. __________________ Even if the voices aren't real, they have some pretty good ideas.

May 17th, 2006, 8:26 PM	#8
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>what do i just choose a random memory location Something like that. You declare enough space. >Can you demonstate this Narue please. Oh, very well. This is FASM though, I don't have A86: (Toggle Plain Text) format MZ org 100h jmp start save db 4 dup '$' start: mov ax,123 mov bx,10 mov di,2 convert: mov dx,0 div bx add dx,'0' mov [save+di],dl dec di test ax,ax jnz convert ; Display the result mov ah,09h mov dx,save int 21h ; Finish up mov ah,4Ch mov al,0 int 21h format MZ org 100h jmp start save db 4 dup '$' start: mov ax,123 mov bx,10 mov di,2 convert: mov dx,0 div bx add dx,'0' mov [save+di],dl dec di test ax,ax jnz convert ; Display the result mov ah,09h mov dx,save int 21h ; Finish up mov ah,4Ch mov al,0 int 21h __________________ Even if the voices aren't real, they have some pretty good ideas.

May 16th, 2006, 4:54 PM	#3
kruptof Professional Programmer Join Date: May 2006 Location: UK - London Posts: 333 Rep Power: 3	thanks Narue........i understand and know about the adding the 48 trick but i don't understand the moduls/division operation that you have mentioned. perhaps you can give a simple demonstation of that. okay sorry Narue just took a moment to digest what you have suggested.......and know i understand what you were implying..........but know how do get the remainder of a division operation in ASM .......i am using A86 if that helps. Thanks for the help so far Narue

May 17th, 2006, 6:02 AM	#7
kruptof Professional Programmer Join Date: May 2006 Location: UK - London Posts: 333 Rep Power: 3	what do i just choose a random memory location, and if i do wouldn't there be a possibilty that another program is using that memory location. Can you demonstate this Narue please.

May 18th, 2006, 12:00 PM	#9
kruptof Professional Programmer Join Date: May 2006 Location: UK - London Posts: 333 Rep Power: 3	wow thanks Narue.............but why did u put 2 in the di regester

May 18th, 2006, 12:07 PM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Endianness. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Programming Forums > Application Development > Assembly

Assembler displaying digits