ASSEMBLY 8086 EXERCISE UNIVERSITY

is anyone able to develop a procedure in an assembly program for intel 8086 processor that reads a vector of integers from data segment and replaces the first DIM/2 elements of the vector with the defined VAL value of the data segment ?

I tried to write something:

STACKSEGMENT SEGMENT PUBLIC 'DATACLASS'
    DB 8 DUP(O)
STACKSEGMENT ENDS
DATASEGMENT SEGMENT PUBLIC 'DATACLASS'
    VECTOR  DW 4 DUP (?)
    DIM     DW 4
    VAL     DW 5
DATASEGMENT ENDS
MYCODESEG SEGMENT PARA PUBLIC 'CODECLASS'
MYPROC PROC NEAR
ASSUME CS: MYCODESEG, DS:DATASEGMENT, SS:STACKSEGMENT

MOV AX, DATASEGMENT
MOV DS, AX
LEA AX, VECTOR
PUSH AX
MOV AX, DIM
PUSH AX
MOV AX, VAL
PUSH AX
CALL MYPROC
ADD SP,10

mov ah, 4Ch
int 21h

MYCODESEG ENDS
END MYPROC
END

MOV AX, DATASEGMENT
MOV DS, AX
LEA AX, VECTOR
PUSH AX
MOV AX, DIM
PUSH AX
MOV AX, VAL
PUSH AX
CALL MYPROC
ADD SP,10

If you're trying to read the contents of VECTOR into AX, this isn't going to do it.

MOV AX, DATASEGMENT
MOV DS, AX

This is correct.

LEA AX, VECTOR
PUSH AX

This, however, won't get you to the contents of VECTOR. LEA stands for "load effective address". Remember that the label VECTOR is just where the data is stored - not the data itself. Essentially you've just done

mov ax, offset VECTOR
push ax

which doesn't really get you any closer to what you want. On this CPU, you actually can't use ax to read from memory like that. Only bx, bp, si, and di can.
So here's what you're really looking for:

MOV AX, DATASEGMENT
MOV DS, AX
LEA SI, VECTOR
MOV AX, [SI]

Putting the brackets around SI is what makes it a memory load operation. This takes the first 16-bit value in your vector array and loads it into AX. Without the brackets there, i.e. MOV AX, SI, you'd just be moving the address of your vector array into AX which doesn't achieve anything.

Now that being said, you declared VECTOR as VECTOR DW 4 DUP (?) which tells the assembler "I need 4 words of space here, but I don't care what the values are right now because the code I'm going to write is going to fill them in." So reading that data right from the start isn't going to accomplish anything of value. You'll get something into ax with the code example above, but there's no guarantee that the data you get has any real meaning.