x86-16

We have given an instruction to make the the text CSC 112.1 to be centered. I used DB instruction and offset. This is my code .model small .stack .data c db 10,13,10,13," лллл ",10,13 db " лллллл ",10,13 db "лл лл",10,13 db "лл ",10,13 db "лл ",10,13 db "лл ",10,13 db "лл ",10,13 db "лл ",10,13 db "лл ",10,13 db "лл лл",10,13 db " лллллл ",10,13 db " лллл ",10,13,"$" .code mov ax,@data mov ds,ax call ccall ;call the procedure ccall which outputs C call scall ;call the procedure scall which outputs S call numcall ;call the procedure numcall which outputs 112.1 call exit ;call the procedure exit

SEG A : Assigns the content held in segment register corresponding to the segment in which A resides to the operand. I guess that means that if A lies in Data Segment, SEG A is the same as DS . Since DS holds the base address of the Data Segment, does MOV AX, LEA A MOV DX, SEG A MOV AX, [AX + DX] copy the physical address of A to AX ? I guess that means that if A lies in Data Segment, SEG A is the same as DS. Correct, if DS points to Data Segment. does MOV AX, LEA A MOV DX, SEG A MOV AX, [AX + DX] copy the physical address of A to AX? The last instruction is invalid, it does not exist in any

mov dx, offset buffer mov ah, 0ah int 21h jmp print buffer db 10,?, 10 dup(' ') print: xor bx, bx mov bl, buffer[1] mov buffer[bx+2], '$' mov dx, offset buffer + 2 mov ah, 9 int 21h I know buffer[bx+2] stands for '$', but offset buffer +2 in mov ah,9 stands for what? They said, "Start printing from address DS:DX + 2 ". From address ds:dx +2 . When a string is captured from keyboard with int 21h, ah=0Ah, the string has next structure: As you can see, the first two bytes are control, the characters entered by user start at the third byte (byte 2). The last char is chr(13) (ENTER key). To display

I need to develop a procedure for Assembly language and call that procedure from C language (pass a string and return an integer value). My assembly procedure works fine "stand-alone". I need help with connecting them together. Program is supposed to run on Intel 8086. I need to use MASM or emu8086 as assembler/simulator. Kindly recommend a C compiler and also a way to make the simple C program that is able to call the assembly procedure and get the returned value. How can I pass a string to this external function? How can I connect the ASM file and the C file? (How will the compiler know

What addressing mode is used in "mov cx, [bp+6]"? The processor is intel 8086. I am studying "Microprocessor and Interfacing" by Douglas V. Hall. I know its memory addressing mode. But not sure whether its based addressing mode or index addressing mode? [bp+6] is the based addressing mode. From the original 8086 docs: In based addressing, the effective address is the sum of a displacement value and the content of register BX or register BP. Indexed addressing mode is similar but with the SI or DI registers. Basically, you have the following modes: Direct memory accessing like [1234] . Register