DaniWeb IT Discussion Community http://www.daniweb.com/forums/ Tech support, programming, web development, and internet marketing community. Forums to get free computer help and support. en-US Wed, 09 Dec 2009 11:40:30 GMT vBulletin 60 http://www.daniweb.com/alphaimages/misc/rss.jpg DaniWeb IT Discussion Community http://www.daniweb.com/forums/ With permission pLeAsE... http://www.daniweb.com/forums/thread240112.html Fri, 20 Nov 2009 22:40:46 GMT Give me convience or give me death! The would-be programmer is introduced in some way to what could be compared to a CS101 course. He is taught about algorithms, variables, procedures, recursive functions, data structures and arrays. One of the fundamental steps for any program... Give me convience or give me death!

The would-be programmer is
introduced in some way to what could
be compared to a CS101 course.
He is taught about algorithms,
variables, procedures, recursive
functions, data structures and arrays.
One of the fundamental steps for
any program development is ease of
program development through
incremental stages of implementation
and testing and the all to important
methods for procedural abstraction.
This world is indefinitely growing,
complicated, complex and diverse.
But it doesn't require a genuis to
be a programmer, nearly anyone can
be trained to be a programmer and the
computer science courses offered by
universities train a person with
no knowledge of programming from the
ground up.
Coding is complex but there are many
steps that are technically
unnecessary but make programming
easier, these steps become
necessities and there are very few
programmers that can go without them.
Convience is necessary to make
programming even practical, the
more convience a programmer has the
better programmer he can be.
Compilers, linkers, libraries,
loaders, operating enviroments,
device independence, all these things
are for convience and without them
the world would not be what we see
today.

In the end its just electromagnetic
radiation messing with your brain.

Coder 3y3ty, "Give me convience or give me death!"
happy coding,
and good day. ]]> Assembly NotNull http://www.daniweb.com/forums/thread240112.html TSR Help... http://www.daniweb.com/forums/thread233279.html Mon, 26 Oct 2009 00:37:01 GMT
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



int1c:

push ds

push ax

push cs

pop ds

call checkdos2

jc int1c_e

cmp byte [hotkey_found], 1

jnz int1c_e

call tsrapp

int1c_e:

pop ax

pop ds

iret



int28:

push ds

push ax

push cs

pop ds

call checkdos

jc int28_e

cmp byte [hotkey_found], 1

jnz int28_e

call tsrapp

int28_e:

pop ax

pop ds

iret



checkdos2:

push bx

push es

les bx, [InDOS]

mov al, 0

cmp al, byte [es:bx]

jb checkdos2_e

cmp al, byte [es:bx-1]

checkdos2_e:

pop es

pop bx

ret



checkdos:

push bx

push es

les bx, [InDOS]

mov al, 1

cmp al, byte [es:bx]

jb checkdos_e

xor al, al

cmp al, byte [es:bx-1]

checkdos_e:

pop es

pop bx

ret



InDOS      dd 0

Orig_isr9  dd 0

in_isr9    db 0

hotkey_found db 0

hotkey_idx dw 0

hotseq     db 0x1b



isr9:

push ds

push bx

push ax

push cs

pop ds

in al, 0x60

pushf

cli

call word far [Orig_isr9]

mov ah, [in_isr9]

or ah, [hotkey_found]

jnz isr9_e

inc byte [in_isr9]

cmp al, byte [hotseq]

jz isr9_foundkey

jmp isr9_exit

isr9_foundkey:

mov byte [hotkey_found], 1

isr9_exit:

dec byte [in_isr9]

isr9_e:

pop ax

pop bx

pop ds

iret



tsrapp:

push dx

mov ah, 0x2

mov dl, 0x41

int 0x21

pop dx

ret



pre equ $



init.tsr:

mov ax, 0x3509

int 0x21

mov [Orig_isr9], bx

mov [Orig_isr9+2], es

mov dx, isr9

mov ax, 0x2509

int 0x21

mov dx, int28

mov ax, 0x2528

int 0x21

mov dx, int1c

mov ax, 0x251c

int 0x21

mov ax, 0x3400

int 0x21

mov [InDOS], bx

mov [InDOS+2], es

mov dx, pre

add dx, 0xf

shr dx, 4

mov ax, 0x3100

int 0x21
]]> Assembly NotNull http://www.daniweb.com/forums/thread233279.html 80x86 Word Memory Access http://www.daniweb.com/forums/thread232493.html Fri, 23 Oct 2009 03:34:17 GMT 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 of the first byte of the word lies at an even address the processor can pull in both bytes of the... 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 of the first byte of the word lies
at an even address the processor can pull in both bytes
of the word in one memory fetch.

If the first word of an array of words lies at an even
address so will every other word in the array.
1st Word__2nd Word__3rd Word
|0100|0101|0102|0103|0104|0105
^________^________^_______
This speeds up performance when accessing an array
of words.

Assemblers usually provide an ALIGN directive to align
a word at an even address.

I was looking through the i386 arch manual on this, and
it mentioned that there could be a slight increase in speed
when the target address of control transfer instructions
were evenly divisible by four, does this apply to the 8086/real-mode?


Good day.
]]> Assembly NotNull http://www.daniweb.com/forums/thread232493.html Code Snippet Passive TSR Hello World http://www.daniweb.com/code/snippet226609.html Tue, 29 Sep 2009 19:21:10 GMT Assembles under NASM 16-bit, invoke INT 0x65 to display message. Assembles under NASM 16-bit,
invoke INT 0x65 to display message. ]]> Assembly NotNull http://www.daniweb.com/forums/thread226609.html Load User gen Char set ... http://www.daniweb.com/forums/thread224434.html Sun, 20 Sep 2009 18:35:27 GMT
Load a user generated character set, should work on
computers equipped with VGA cards.
Assembles with 16-bit NASM as an absolute binary image (.COM).

bits 16

org 100h

             jmp word drip0_start

    char_set: times 416 db 0

    msg       db '0o l0^d user char generated',0xd,0xa

              db 'bitmaps can also be used....',0xd,0xa,0x24

       drip0_start:

             mov ax, 0x1a00 ; is VGA/MCGA supported?

             int 0x10

             cmp al, 0x1a 

             jnz drip0_end  ; no. then exit

             mov ax, 0x13   ; set video mode to 13h

             int 0x10        

             mov ax, 0x3    ; back to text-mode

             int 0x10

             mov ax, 0x1130 ; Return current character set

             mov bh, 0x7    ; 9*16 char set

             int 0x10

             push ds       ; Returns ptr to char set in ES:BP

             push es       ; Swap DS & ES to copy char set in data area

             pop ds

             pop es

             add bp, 0x410

             mov di, char_set

             mov si, bp

             cld

             mov cx, 0x1a0 ; copy 416 bytes

             rep movsb

             push ds

             push es

             pop ds

             pop es

             mov bx, char_set

       char_modify:   

             mov al, 0x40     ; used to set bit 6

             or [bx+0xb], al  ; done here

             mov [bx+0xe], al

             mov [bx+0xd], al

             mov [bx+0xc], al

             add bx,byte +0x10 ; add 16 to offset in BX

             cmp bx,0x293      ; 293 = offset of the

                                              ; first byte of last 16 bytes

             jg load_user_gen_char

             jmp short char_modify

       load_user_gen_char:

             push ds

             push es

             pop ds

             pop es

             mov bp, char_set ; ES:BP pointer to user gen chars

             mov cx, 0x1a ; Change 26 characters

             mov dx, 0x41 ; Begin at ASCI char 'A' dec: 65

             mov bh, 0x10 ; Font Bitmap 16 bytes in length

             xor bl, bl   ; table zero

             mov ax, 0x1100  ; Load User Generated Char Set

             int 0x10

             push ds

             push es

             pop ds

             pop es

             mov ax, 0x1130  ; Return Character Set

             mov bh, 0x7     ; 9*16 Character Set

             int 0x10

             push ds

             push es

             pop ds

             pop es

             add bp, 0x610

             mov di, char_set

             mov si, bp

             cld

             mov cx, 0x1a0   ; Copy 416 bytes

             rep movsb

             push ds

             push es

             pop ds

             pop es

             mov bx, char_set

      char_modify2:

             mov al, 0x40

             or [bx+0xb], al

             or [bx+0xc], al

             or [bx+0xd], al

             or [bx+0xe], al

             add bx, byte +0x10

             cmp bx, 0x293   ; offset of the last 16 bytes in char_set

             jg load_user_char_gen2

             jmp short char_modify2

      load_user_char_gen2:

            push ds

            push es

            pop ds

            pop es

            mov bp, char_set  ; ES:BP user gen char set

            mov cx, 0x1a  ; Change 26 characters

            mov dx, 0x61  ; starting at ASCI char 'a' dec. 97 

            mov bh, 0x10  ; 16 bytes per font bitmask

            xor bl, bl    ; table zero

            mov ax, 0x1100 ; Load User Generated Character Set

            int 0x10

            push es

            pop ds

            mov ah, 0x9

            mov dx, msg

            int 0x21

            wait_key:

            mov ah, 0x6

            mov dl, 0xff

            int 0x21

            jz wait_key

      drip0_end:  

            mov ax, 0x4c00

            int 0x21

Comments or corrections are welcome.
]]> Assembly NotNull http://www.daniweb.com/forums/thread224434.html Array... http://www.daniweb.com/forums/thread222541.html Sat, 12 Sep 2009 16:09:34 GMT
arr db 1,2,3,4,5
mov bx,offset arr
add bx,4
mov al,[bx]
Is this correct?????????
]]> Assembly NotNull http://www.daniweb.com/forums/thread222541.html Addressing... http://www.daniweb.com/forums/thread222388.html Fri, 11 Sep 2009 23:57:38 GMT Some 16-bit stuff... A segment address is bit shifted to the left by four bits to form a 20-bit physical address and a 16-bit offset is added to the result to index into a segment. So 1234:0100 would create the physical address 12440 Some 16-bit stuff...

A segment address is bit shifted to the left
by four bits to form a 20-bit physical address
and a 16-bit offset is added to the result to
index into a segment.

So 1234:0100 would create the
physical address 12440

Is this correct???????????
]]> Assembly NotNull http://www.daniweb.com/forums/thread222388.html