write the code in assembly programming with PIC$16$F$877$ microprocessor

i work in MPLAB IDE v$8\mathrm{.}92$

i want to build "model" of a $4-$bit microprocessor which includes the following units:

ALU, I$/$O $-$ LCD display, button matrix and memory

Operation description of the units: Data reception: $-$ the $2$ operands, $4$ bits and the operation CODE OP$,4$ bits are obtained through a matrix of buttons $($in binary$).$Only buttons $0,1$ and A$,$B$,$C can be used.

example :

C B A

The first number will be recorded in the address $0$x$30$ the second in $0$x$40$ and the type of operation in $0$x$50.$

In case of entering an incorrect operation code, "ERROR" will be shown on the display

The received numbers should be displayed on the LCD in the top row

According to the CODE OP$,$ the ALU unit recognizes the operation and executes the command:

$001$ : A$-$B the result in $0$x$60($value and sign$)$

$010$: A$*$B multiplication the result in $0$x$60$

$011$: A$/$B just a whole part the result in $0$x$60$

$100$: A$^$B the result in $0$x$60$

$101$: the number $"1"$ in B the result in $0$x$60$

$110$ : the number $"0"$ in A the result in $0$x$60$

The result of the operation must be displayed on the LCD in the second line. this is my lcd code :LIST P$=$PIC$16$F$877$

include P$16$f$877.$inc

$\_\_$CONFIG $\_$CP$\_$OFF & $\_$WDT$\_$OFF & $\_$BODEN$\_$OFF & $\_$PWRTE$\_$OFF & $\_$HS$\_$OSC & $\_$WRT$\_$ENABLE$\_$ON & $\_$LVP$\_$OFF & $\_$DEBUG$\_$OFF & $\_$CPD$\_$OFF

; LCD

;

org $0$x$00$

reset goto start

org $0$x$10$

start bcf STATUS, RP$0$

bcf STATUS, RP$1$ ;Bank $0$

clrf PORTD

clrf PORTE

bsf STATUS, RP$0$ ;Bank $1$

movlw $0$x$06$

movwf ADCON$1$

clrf TRISE ;porte output

clrf TRISD ;portd output

bcf STATUS, RP$0$ ;Bank $0$

call init

;$----------------------------*------------------------------$

movlw $0$xC$4$ ;PLACE for the data on the LCD

movwf $0$x$20$

call lcdc

call mdel

movlw $0$x$2$A ; CHAR $($the data $)$

movwf $0$x$20$

call lcdd

call mdel

;$----------------------------------------------------------$

wait goto wait

;

;subroutine to initialize LCD

;

init movlw $0$x$30$

movwf $0$x$20$

call lcdc

call del$\_41$

movlw $0$x$30$

movwf $0$x$20$

call lcdc

call del$\_01$

movlw $0$x$30$

movwf $0$x$20$

call lcdc

call mdel

movlw $0$x$01$ ; display clear

movwf $0$x$20$

call lcdc

call mdel

movlw $0$x$06$ ; ID$=1,$S$=0$ increment,no shift $000001$ ID S

movwf $0$x$20$

call lcdc

call mdel

movlw $0$x$0$c ; D$=1,$C$=$B$=0$ set display $,$no cursor, no blinking

movwf $0$x$20$

call lcdc

call mdel

movlw $0$x$38$ ; dl$=1(8$ bits interface,n$=12$ lines,f$=05$x$8$ dots$)$

movwf $0$x$20$

call lcdc

call mdel

return

;

;subroutine to write command to LCD

;

lcdc movlw $0$x$00$ ; E$=0,$RS$=0$

movwf PORTE

movf $0$x$20,$w

movwf PORTD

movlw $0$x$01$ ; E$=1,$RS$=0$

movwf PORTE

call sdel

movlw $0$x$00$ ; E$=0,$RS$=0$

movwf PORTE

return

;

;subroutine to write data to LCD

;

lcdd movlw $0$x$02$ ; E$=0,$ RS$=1$

movwf PORTE

movf $0$x$20,$w

movwf PORTD

movlw $0$x$03$ ; E$=1,$ rs$=1$

movwf PORTE

call sdel

movlw $0$x$02$ ; E$=0,$ rs$=1$

movwf PORTE

return

;$----------------------------------------------------------$

del$\_41$ movlw $0$xcd

movwf $0$x$23$

lulaa$6$ movlw $0$x$20$

movwf $0$x$22$

lulaa$7$ decfsz $0$x$22,1$

goto lulaa$7$

decfsz $0$x$23,1$

goto lulaa$6$

return

del$\_01$ movlw $0$x$20$

movwf $0$x$22$

lulaa$8$ decfsz $0$x$22,1$

goto lulaa$8$

return

sdel movlw $0$x$19$ ; movlw $=1$ cycle

movwf $0$x$23$ ; movwf $=1$ cycle

lulaa$2$ movlw $0$xfa

movwf $0$x$22$

lulaa$1$ decfsz $0$x$22,1$ ; decfsz$=12$ cycle

goto lulaa$1$ ; goto $=2$ cycles

decfsz $0$x$23,1$

goto lulaa$2$

return

mdel movlw $0$x$0$a

movwf $0$x$24$

lulaa$5$ movlw $0$x$19$

movwf $0$x$23$

lulaa$4$ movlw $0$xfa

movwf $0$x$22$

lulaa$3$ decfsz $0$x$22,1$

goto lulaa$3$

decfsz $0$x$23,1$

goto lulaa$4$

decfsz $0$x$24,1$

goto lulaa$5$

return

endand this is my keyboard code :LIST P$=$PIC$16$F$877$

include

$\_\_$CONFIG $\_$CP$\_$OFF & $\_$WDT$\_$OFF & $\_$BODEN$\_$OFF & $\_$PWRTE$\_$OFF & $\_$HS$\_$OSC & $\_$WRT$\_$ENABLE$\_$ON & $\_$LVP$\_$OFF & $\_$DEBUG$\_$OFF & $\_$CPD$\_$OFF

org $0$x$00$

reset: goto start

org $0$x$10$

start: bcf STATUS,RP$0$

bcf STATUS,RP$1$ ;Bank$0$

clrf PORTD

bsf STATUS,RP$0$ ;Bank$1$

bcf INTCON,GIE ;No interrupt

movlw $0$x$0$F

movwf TRISB

bcf OPTION$\_$REG,$0$x$7$ ;Enable PortB Pull$-$Up

clrf TRISD

bcf STATUS,RP$0$ ;Bank$0$

;$--------------------------------------------------------------------------------------------------$

main: call wkb

movwf PORTD

goto main

;$--------------------------------------------------------------------------------------------------$

wkb: bcf PORTB,$0$x$4$ ;scan Row $1$

bsf PORTB,$0$x$5$

bsf PORTB,$0$x$6$

bsf PORTB,$0$x$7$

btfss PORTB,$0$x$0$

goto kb$01$

btfss PORTB,$0$x$1$

goto kb$02$

btfss PORTB,$0$x$2$

goto kb$03$

btfss PORTB,$0$x$3$

goto kb$0$a

bsf PORTB,$0$x$4$

bcf PORTB,$0$x$5$ ;scan Row $2$

btfss PORTB,$0$x$0$

goto kb$04$

btfss PORTB,$0$x$1$

goto kb$05$

btfss PORTB,$0$x$2$

goto kb$06$

btfss PORTB,$0$x$3$

goto kb$0$b

bsf PORTB,$0$x$5$

bcf PORTB,$0$x$6$ ;scan Row $3$

btfss PORTB,$0$x$0$

goto kb$07$

btfss PORTB,$0$x$1$

goto kb$08$

btfss PORTB,$0$x$2$provide me the full code! not a template