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That was easy.I hope.If you could not get it fair and square, I have some eBooks as links in the home page. Just check out them and come back.
It is the main assembly struc, but it can be much more complex. now in the sseg (stack) there was "db". what is that? well if (most of the times) assembly registers are not enough so you (like pascal,c) can define variables, how ?
well you have the operators - db,dw,dd,dt :
DB - define byte, the var will be 1 byte (8 bit) DW - define word, the var will be 2 bytes (word, 16 bit) DD - define double, the var will be 4 bytes (double word,32 bit) DT - define ten, then var will be 10 bytes (not used) the decleration goes like this : name type [number] value. examples : try db 1 - it will define "try" as 1 byte with starting value 1 tru dw 4 - it will define "tru" as 2 byte with starting value 4 ytu dw ? - it will define "ytu" as 2 byte with unknown starting value now lets say that you want to define an array (like pascal : a:array[1..10]of like c : int c[100]) you do as follow : name type number dup(value). lets say : gvr db 10 dup(2) - it will define "gvr" as 10 byte which each one has value of 2. but what if I want to define a messege or multiple values then what ?? then it should be like : messege - mes db "this is a messege",10,13,"$" now the numbers after the second """ are optional, it's needed only for some interrupt. multiple values (vectors, etc.) then : vec db 23,54,76,34,234,14,23,123,245 db 124,34,245,23,52,34,52,43,13 db 213,213,123,123 the db can be dw,dd or dt, and you can do it for how much you want but you must not pass the 64k limit. but what if you want to write a messege then ??? you will search the int which do that : int 21h - write string ah - 9 ds:dx points to string (in the end "$" for termination) so how will we do it ???
Sseg segment db 10 dup (?) ends Dseg segment msg db "dr. encryption",10,13,"$" ; for termination ends Cseg segment assume cs:cseg,ds:dseg,ss:sseg start : ; the compiler will start here mov dx,offset msg ; ds is already pointing to dseg mov ah,9 int 21h ; whop there he is mov ah,4ch mov al,0 int 21h ; terminate ends ; the segment must finish before the label end start ; close the label end ; tell compiler script ends here
now what offset is, well offset will return the offset of the argument so if you write : mov dx,offset msg then dx will be the offset of the msg (offset is 16bit and so is segment ,so "mov al,offset ..." will be wrong) the operator seg will return the segment of the argument, but if you change ds and not return his original value the system will hang. so then the stack comes to buisness.
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