Question

Write a Marie or MASM program which sums the numbers from 1 to N, where you choose N. For extra credit nmake it a subroutine and call it several times.

Answer 1

Assume DS: Data ,CS:Code

Data Segment

TABADR DW 6000H

COUNT DB 05H

Data Ends

Code Segment

Start:

MOV AX,Data

MOV DS,AX

MOV SI,TABADR

MOV CL,COUNT

Loop1:MOV AL,[SI]

ADD BL,AL

INC SI

DEC CL

JNZ Loop1

INT 03H

Code Ends

End Start

STEP BY STEP EXPLANATION OF PROGRAM IS GIVEN BELOW:

--Here,Assume is an assembler directive which tells the start of the programby assuming cs as code segment and ds as data degment.

--'Data Segment' tells the start of data segment.

--TABADR stands for tab address and DW stands for define word i.e we are setting TABADR equal to 6000H.

--DB stands for define byte and the value of COUNT is set to 05H.

--DATA ENDS signifies the end of data segment.

--'Code Segment' tells the start of code segment.

--Since,we cannot put anything directly into segment registers such as DS.So we first initialize AX with the value 'Data' segment address and then move value of AX into DS.

--SI is initialised with the value of TABADR i.e 6000

--CL is a counter reg and hence initialized with count value i.e 05.

--The data  at 6000H (i.e the value of SI) is then moved to AL reg.

--ADD AL with contents of BL and store the result in BL.

--Then we increment SI so that it now points to next address location

--And simultaneously we decrement CL bcoz we have read one value.

--We then apply a jump condition to the loop Loop1 unitl the value of CL becomes zero.

--If CL becomes zero it comes out of the loop and runs the instruction INT 21H,which is actually a break point interrupt which stops the execution.

--Then the code segment ends.

Here, a subroutine is made in the form of a loop to call the statements again and again.