Question

Write a program in assembly code (8088/8086) to determine the Average, Highest, Lowest grade in microprocessor course (final grade =100) if the class has 30 students. Write the program in the emulator(8086) and show the input data and the results (Average grade- Highest grade- Lowest Grade).

Note: Suppose the grades of the 30 students.

Answer 1

Hello!

AX, BX , CX and DX are 16 bit general purpose registers.

AX is also called as accumulator. any operation like division and ultiplication the result is stored in accumulator(AX)

We can have have 8 bits by refering X with L or H like AH and AL both are 8 bit registers AX = AH + AL , where H represent Higher byte L represents lower byte.

MOV operand 1, operand 2

In this instruction first operand mush be register(AX,AL,AH,BX...) or memory location([DI],[SI]) , second operand can be immediate data or register or memory location.

Ex:

MOV AX, 0015h

MOV [4000h],12h

DB , DW are directives

Directives are used to store inforamtion in the memory

Here i have taken org 100h the program is utilising after first 2 bytes so now our 1st word starts storing at 102h offset address.

var_name db value1,value2,.......value n

Byte(8bits)

In 8086 you can store the data into memory using variables here var_name is a variable so it will allocate the 1 byte memory to the values

var_name dw value1,value2,.......value n

Word(16bits or 2 bytes)

Here var_name is a variable so it will allocate the 2 bytes memory to the all the values

var_name db ?

This creates a variable with no data assigned to it so use ? when dont have clue store which value in varaible.

NOTE: values can be number or charecters or string

VAR_NAME , var_name both are same, 8086 is not case sensitive

ADD operand 1, opearand 2

This instruction add the operand 1 and operand 2 and result stores back to the operand 1.

In this instruction operand 1 must not be immediate value but it can be a register and memory location.

Operand 2 can be any thing register or memory location or register.

Ex:

ADD Cl , 05h

ADD [SI] , 45h

ADD 78h, AX ; first operand must not be immediate value

ADD [DI],Var1 ; both operands must not be addresses

Procedures:

Procedures helps us in code reusability , its similar to functions sometimes same instructions we need to execute for different data in that situation we can use procedures

SYNTAX :

procedure_name PROC

; code

RET

procedure_name ENDP

LOWER ADDRESS BITS GOES TO LEAST SIGNIFICANT BITS.

HIGHER ADDRESS BITS GOES TO MOST SIGNIFICANT BITS.

When var dw 458Bh the data stores at lower loaction lets take DS:0100h is 8Bh and higher loaction that is DS:0101 is 45h

DIV operand

This instruction divides the value accumulator with opearndand result stores back to the Accumulator.

IF 16 bit

AX stores the Quotient

DX stores the Remainder

AX = AX / operand

IF 8 bit

AL stores the Quotient

AH stores the Remainder

AL = AL / operand

Here operand must be Register or Memory location but not immediate data.

EX:

DIV BH ; AH = AH / BH

DIV [5500h]

DIV 0Ah ; should not use immediate value

JNE main ; if zero flag is 0 then goes to main lable

JMP exit ; jumps to the exit of the code

LOGIC:

AVERAGE

• Goes to each score add to the AX
• Each score gets stored to BX
• Adds AX and BX
• finally divides with cx (number of scores)

MAX or MIn

• assumes first score is max or min
• from second element it compares the assumed value
• if it is max or min then it wil upadate the max or min
• stores the max or min

CODE:

org 100h   
 
; JUMPS O START OF MAIN PROGRAM 
JMP START

; ALL SCORES STORES IN SCORES ARRAY
SCORES DB 98d,85d,69d,50d,79d,58d,30d,80d,96d,36d,84d,56d,94d,89d,67d
; NUMBER OF SCORES IN THE ARRAY
COUNT DB 15d
; AVERAGE OF SCORES 
AVERAGE DB ?
; MAX OF SCORES
MAX DB ?
; MINIMUM OIF SCORES
MIN DB ?

START:  

; AVERAGE

MOV DI,offset SCORES     ; loads offset address to DI
MOV AX,00h               ; Makes A to 0
MOV CL,[COUNT]           ; Gets the data in count variable
L1:
MOV BX,00                ; Makes BX to 0
MOV BL,[DI]              ; moves data in the loactaion to BL
ADD AX,BX                ; Adds the scores with total scores
INC DI                   ; goes to nest scores location
LOOP L1                  ; loop continues till Cx becomes 0

MOV CL,[COUNT]           ; Gets data to CL
DIV CX                   ; Ax = AX / CX
MOV [AVERAGE],AL         ; moves the average of scores to AVerage variable

; HIGHEST

MOV DI, offset SCORES    ; gets the offset address of scores
MOV AL,[DI]              ; Assumes the first element is the max of scores
MOV CL,[COUNT]           ; gets the count to cx 
DEC CL                   ; Decrements the cl values as we need only 14 comparisons not 15 
HIGH: 
INC DI                   ; goes to next location
CMP AL,[DI]              ; compares the value in AL with next loaction data
JG SKIP                  ; If greater skips the below contidition
MOV AL,[DI]              ; Updates the AL value (max value) of scores
SKIP:                    
LOOP HIGH                ; Loops untill all 14 comparisions are completed
MOV [MAX],AL             ; Moves the maximum value of scores to MAX variable

; LOWEST  

MOV DI, offset SCORES    ; gets the offset address of scores
MOV AL,[DI]              ; Assumes the first element is the min of scores
MOV CL,[COUNT]           ; gets the count to cx 
DEC CL                   ; Decrements the cl values as we need only 14 comparisons not 15 
LOW:
INC DI                   ; goes to next location
CMP AL,[DI]              ; compares the value in AL with next loaction data
JNG SKIP0                ; If not greater skips the below contidition
MOV AL,[DI]              ; Updates the AL value (min value) of scores
SKIP0:                    
LOOP LOW                 ; Loops untill all 14 comparisions are completed

MOV [MIN],AL             ; Moves the minimum value of scores to MIN variable

HLT

    

emu8086 - assembler and microprocessor emulator 4.08 file edit bookmarks assembler emulator math ascii codes help ? E new open examples save compile emulate calculator convertor options help about 01 org 100h 02 03 ; JUMPS O START OF MAIN PROGRAM 04 JMP START 05 06 ; ALL SCORES STORES IN SCORES ARRAY @? SCORES DB 980, 850,690,500,790,58d, 300, 800,960, 360,840,560,940,890,67d 08 ; NUMBER OF SCORES IN THE ARRAY 09 COUNT DB15d 10 ; AVERAGE OF SCORES 11 AVERAGE DB ? 12 ; MAX OF SCORES 13 MAX DB ? 14 ; MINIMUM OF SCORES 15 MIN DB ? 16 17 START : 18 19 ; AVERAGE 20 21 MOV DI,offset SCORES ; loads offset address to DI 22 MOU AX, 00h ; Makes A to 23 MOU CL, [COUNT ] ; Gets the data in count variable 24 L1: 25 MOV BX,00 ; Makes BX to o 26 MOU BL, IDI ] ; moves data in the loactaion to BL 27 ADD AX, BX ; Adds the scores with total scores 28 INC DI ; goes to nest scores location 29 LOOP L1 loop continues till Cx becomes ] 30 31 MOV CL, [COUNT] ; Gets data to CL 32 DIV CX ; Ax = AX CX 33 MOV [AVERAGE], AL moves the average of scores to Average variable 34 35 ; HIGHEST 36 37 MOU DI, offset SCORES ; gets the offset address of scores 38 MOV AL, [DI] ; Assumes the first element is the max of scores 39 MOU CL, [COUNT ] ; gets the count to cx 40 DEC CL ; Decrements the cl values as we need only 14 comparisons not 15 41 HIGH: 42 INC DI ; goes to next location 43 CMP AL, IDI ] ; compares the value in AL with next loaction data 44 JG SKIP ; If greater skips the below contidition 45 MOU_AL, [DI] Updates the AL value (max value) of scores 46 SKIP: 47 LOOP HIGH ; Loops untill all 14 comparisions are completed 48 MOU [MAX ], AL ; Moves the maximum value of scores to MAX variable 49 50 ; LOWEST 51 52 MOV DI, offset SCORES ; gets the offset address of scores 53 MOU AL, IDI ] Assumes the first element is the min of scores 54 MOV CL, [COUNT ] gets the count to cx 55 DEC CL ; Decrements the cl values as we need only 14 comparisons not 15 56 LOW: 57 INC DI goes to next location 58 CMP AL,[DI] compares the value in AL with next loaction data 50 INC SKIPA If not Antoneline the halon Antiditinn - line: 29 col: 74 drag a file here to open

emu8086 - assembler and microprocessor emulator 4.08 file edit bookmarks assembler emulator math ascii codes help ? help E about compile emulate calculator convertor options ; gets the offset address of scores ; Assumes the first element is the max of scores ; gets the count to CX ; Decrements the cl values as we need only 14 comparisons not 15 goes to next location compares the value in AL with next loaction data If greater skips the below contidition Updates the AL value (max value) of scores ; Loops untill all 14 comparisions are completed ; Moves the maximum value of scores to MAX variable new open examples save 34 35 ; HIGHEST 36 37 MOU DI, offset SCORES 38 MOU AL, [DI] 39 MOU CL, ICOUNT ] 49 DEC CL 41 HIGH: 42 INC DI 43 CMP AL, [DI] 44 JG SKIP 45 MOV_AL, [DI] 46 SKIP: 47 LOOP HIGH 48 MOU [MAX), AL 49 50 ; LOWEST 51 52 MOU DI, offset SCORES 53 MOU AL, DI] 54 MOU CL, [COUNT ] 55 DEC CL 56 LOW: 57 INC DI 58 CMP AL, [DI] 59 JNG SKIPO 60 MOU AL,[DI 61 SKIPO: 62 LOOP LOW 63 64 MOV [MIN], AL 65 66 HLT 67 68 69 70 ; gets the offset address of scores ; Assumes the first element is the min of scores ; gets the count to cx ; Decrements the cl values as we need only 14 comparisons not 15 ; goes to next location ; compares the value in AL with next loaction data ; If not greater skips the below contidition Updates the AL value (nin value) of scores ; Loops untill all 14 comparisions are completed ; Moves the minimum value of scores to MIN variable

OUTPUT:

2 3 en AL, MIN HIG em 65 n e variables X ate original source co... X but GHES 52 MOU DI, offset SCORES size: byte elements: 1 53 MOU AL, [DI] DI, of 54 MOU CL, [COUNT ] AL, edit show as: unsigned the 55 DEC CL ores CL, COI 56 LOW: CL ts 57 INC DI 1: SCORES 98 58 CMP AL, IDI 1 4 compari DI COUNT 15 nex 59 JNG SKIPO AL, AVERAGE 71 th 60 MOVAL, DI ] ЕКІР MAX 98 n data 61 SKIPO: er 30 the 162 LOOP LOW 63 till 64 MOU [MIN], AL leted [MAX ariable 66 HLT WEST) DI, offset SCORES : gets the offset address of scores AL, CL, emulator: noname.com res Х CL file math debug view external virtual devices virtual drive help compari DI AL, IL data SKI Load reload step back single step run step delay ms: 0 AL, registers HL 9700:0114 9786: 9166 ted [MI AX 90 1E 97114: 1E 030 A MOU DI, 00102h riable 07115: BF 191 1 MOU AL, [DI BX | 89 43 07116: 02 002 0 MOU CL, 100111h) 07117: 01 001 DEC CL CX | |ចទ្ធ 07118: B8 184 1 INC DI 07119: 00 000 NULL CMP AL, IDI 1 DX 90 36 0711A: 00 000 NULL JLE 015 Bh 0711B: 8A 138 è MOU AL, IDI 1 CS 9796 0711C: GE 014 A LOOP 0154h 0711D: 11 017 MOU (00114h], AL IP 6166 0711E: 01 001 0 SS 0711F: BB 187 1 NOP 9706 07120: 00 000 NULL NOP SP FFFE 07121: 00 000 NULL NOP 07122: 8A 138 è NOP BP OOO6 07123: 1D 029 + NOP 07124: 03 003 NOP SI OOOO 07125: C3 195 F NOP 07126: 47 071 G NOP DI 9116 07127: E2 226 r. NOP 07128: F6 246 NOP DS 9786 07129: 8A 138 è ES 6796 screen source reset debug stack flags LO HLT aux vars

Hope this helps and clear.

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