That's actually kind of funny, I usually have a hard time
not breaking my programs down into procedures.
I think it is essential to know what pieces of code
to encapsulate into procedures and how...

I'm sorry I didn't know that you were required to let the
user enter a fourth character.
So they can enter a variable number of chars up to the
maximum amount,
and always use a termination...

But I know, you are a coder.
Your code does work ;)

MOV A,#8d ; value for the factorial (1-8max)
MOV B,A ; B=A
MOV C,#1d ; C=1
here: ; LOOP
SUB B,C ; B-1
MUL AB ; AxB
CMP B,C ;if B=1

I wrote up an NASM source with similar functions to your
own code. A function for reversing the array, for
adding the two arrays as unpacked BCS, and for entering
values are here. Call to array...

CBW - Convert Byte to Word
Sign extends the byte in AL into the word in AX.
Sign extension is merely copying the sign bit into the rest
of a datatype when a signed value is moved into a larger...

As to storing multiple things in a variable,
a word is really two contiguous bytes:

albl dw 0
;same as
albl2 db 0, 0

and can hold two asci values.
If we reserve room for an array of bytes:

On the MS-DOS system functions for input I usually
use, atimes a Carriage-Return character is at the
end of the buffer lest the maximum count of
characters is met. 21/3F
0xd ends the input, that...

[[[AxxAxLLlaLLLaXBxG]]]]

mov cx, 0x10
mov ax, 0x123
db 0x66
shl ax, cl ; shift 0x123 into high-word of EAX
db 0x66
shr ax, cl ; shift back into low-word of EAX, that is, AX

You would need...

I am trying to create an active TSR which prints an 'A'
when the ESC key is pressed, it doesn't work.
Can anyone tell me what's wrong?


bits 16
org 100h

jmp init.tsr

Func AH=2 INT 13h Disk Services:
CH=Low eight bits of cylinder number
CL=Sector number should start at 1
bits 6-7 represent two high bits of cylinder number (hard disk only).
So the MBR would be...

80X86 Speeding up word memory access.
When the address of the first byte of a word lies
at an odd address the processor must make two memory
fetches for each byte of the word.
But if the address...

IF ESI=OFFSET ARR and Addr ARR=00000100h
[ESI+ESI] -> DS:00000200h 256 bytes past first byte of array

.data
arrayD WORD 10, -60, 30
.code
mov esi, OFFSET arrayD
mov ax, [esi+0] ; AX=10 initialize AX to value of
; first word
add ax,...

mov ds, seg buff ; works in MASM
mov si, offset buff

All you need is the segment address on which the buff string
lies, this is because your generating an .EXE.

Here's one way to wait for a...

mov eax, dword [esi] ;moves first position of array into eax
And also moves a double word EAX=44434241h, I think so,
not sure.


To read each byte at a time do:
xor eax, eax
mov al, byte [esi]...

HLT will save CS:IP or CS:EIP of instruction after hlt
and stop instruction execution until a external interrupt
or NMI is issued.
It puts the processor in a halt state.
HLT is a priviledged...

Give me convience or give me death...

This is 16-bit code, but it should give you the
general idea, the LOOPZ will decrement CX even if the ZeroFlag
is clear (no Zero Result), both LOOPZ and...

To change,
newmem2:
mov eax,0x3e8
so that EAX will be loaded with the value
0x3e8+0x100 replace with:
mov eax,0x3e8+0x100
This varient of mov instruction has immediate as the source
operand,...

You loaded your counter variable starting at counter+2 which
causes the ASCII character 5 to be printed on the screen,
that is the initializer you used for the first byte of the
array at counter:...

The reason jibberish is output to the consol is because
DX is to contain the offset of a dollar-sign '$' terminated string.

mov dx, offset msg
mov ah, 0x9
int 0x21
int 0x20
msg db 'hello...

An Overflow in assembly occurs when the result of
an arithmetic instruction is larger than the destination
operand. For instance, a Divide Overflow occurs when
the quotient is larger than the...

You are indexing into the IVT when interrupts are enabled,
and the timer tick INT 8 calls INT 1c, and INT 8 is called
by external hardware.
This means the interrupt is being called while your...

To print out your commandline arguments with
function 9, simply add a '$' to the end of the actual command tail.
example:

xor bx, bx
mov bl, [0x80]
mov byte [bx+0x81],'$'
mov bx, 0x81

But...

16-bit OS dos I need help vortex reign....
Hello, to answer your question NASM16 is a 16-bit (80x86) assembler
for MS-DOS.
To access commandline parameters, they are passed by the
loader (your...

Another way to print out the value of a byte in hEx is:


printb: ; Byte with value to print is in AL
push ax
shr al, 4
call printasc
pop ax
push ax
and al, 0xf

start:
my_arr db ? ; the instruction pointer is running into junk!!!
mov dl, [my_arr] ; you didn't read any char from the keyboard
mov [my_arr], al
add dl, '0'
mov ah, 2h
int 21h


change...

Color text-mode memory lies at segment 0xb800 and is 4000 bytes
in length 80*25*2 cuz each visible character on the screen
is accompanied by a text attribute byte.
00000000 Text Attribute Byte...

PAINT_A_PIXEL example code...


bits 16
org 100h

start:
mov ax, 0xa000
mov es, ax
call govideo

Suprisingly I did not know that JA was for unsigned
and JG was for signed, etc...
Thanks for the post wildgoose!

Oh I see what you are saying wildgoose!
With packed BCD's you could use the DAS instruction to count-down
in your program using a decimal value...


mov bh, '8'
mov bl, '0'
sub bh, 0x30
sub...

Sorry I made a mistake in my last post,
it should have been 9*10^1


mov cx, 1
mov ax, 10
call pow
mov bx, 9 ; result is in AX
mul bx

Painting pixels, not so much tedious work.

Try MCGA mode 13h you can set this using the video bios,
if you are in 32-bit code try passing down the call to the
BIOS through the DPMI server....

No...
I was implying that you would have to do math.

Here's an example for value 91:

mov al, [char] ; DS:[char]=0x39
sub al, 0x30
xor ah, ah ; base
mov cx, 0xa ; power
call pow

So you used the ASCII value of the digit character in a count
down variable, limiting the number of seconds from 0-9.
Here's how you could use a two digit number:
For 19 for example, this would...

If your looking for an actual hard-wired address you could
use to retrieve the current time, or at least clock ticks,
I think this would be contained in the BIOS data area,
which starts at...

JL or JB / JC ; Jump less-than or jump below
JG or JA ; Jump greater-than or jump above

The CMP instruction subtracts the dest-src from each other,
and updates the FLAGS which can be tested by...

MZ

I have modified your code, and discovered the problem
really was that the string wasn't null-terminated,
this code works:

bits 16
org 100h

start:
mov dx, buf
mov ah, 0xa

I'm sorry if your frustrated, I also notice this:

mov ax,seg buff
mov ds,ax
mov dx,offset buff
mov ah,0ah ; string input
int 21h
push ax ; AH=0Ah AL=last char read
; how is this...

To set up stack 64KB in length for segment number
0x8000, you would load SP with 0000, it may sound strange
but when something is pushed on the stack 0000 will become
FFFE because PUSH decrements...