I wrote a calculator for decimal and binary number systems. Added the ability to work with the hexadecimal number system. It turned out the following: when I perform some operation in the hexadecimal system (+ - / *), then if the result is hexadecimal, that is, letters from A to F, in this case, instead of letters, displays characters. For example: 7D00 * 2 = FA00, but the program displays ?:00, that is, instead of the letter F, displays the character ? , and instead of the letter A displays the symbol :
A - :
B - ;
C - <
D - =
E - >
F - ?
And how can I make the corresponding letter appear instead of a symbol?
This is the program code
LOCALS @@
.model tiny
.code
.386
org 100h
main proc
jmp start
OpMul equ '*'
OpDiv equ '/'
OpAdd equ '+'
OpSub equ '-'
CrLf db 0Dh, 0Ah, '$'
msgAbout db 'Calc', 0Dh, 0Ah
db 'Used', 0Dh, 0Ah
db 'B - binary base', 0Dh, 0Ah
db 'D - decimal base', 0Dh, 0Ah
db 'H - hex base', 0Dh, 0Ah
db '+, -, *, / - operations', 0Dh, 0Ah
db '= or ENTER - show result and quit', 0Dh, 0Ah, '$'
msgChangeBase2 db 08h, 08h, 08h, 08h, 08h
msgBase2 db ' (BIN)', '$'
msgChangeBase10 db 08h, 08h, 08h, 08h, 08h
msgBase10 db ' (DEC)', '$'
msgChangeBase16 db 08h, 08h, 08h, 08h, 08h
msgBase16 db ' (HEX)', '$'
msgPromptExpr db 0Dh, 0Ah, 'Expression: ', '$'
msgResult db 'Result: ', '$'
msgPressAnyKey db 0Dh, 0Ah, 'Press any key to exit...', '$'
Base dw ?
EnBaseChange dw ?
Operand1 dw ?
Operand2 dw ?
Operation db ?
OperationNext db ?
start:
mov ah, 09h
lea dx, [msgAbout]
int 21h
mov ah, 09h
lea dx, [msgPromptExpr]
int 21h
mov [Operand1], 0
mov [Operand1], 0
mov [Operation], OpAdd
mov [EnBaseChange], 1
mov [Base], 10
mov ah, 09h
lea dx, [msgBase10]
int 21h
@@GetCmd:
mov ah, 00h
int 16h
@@IsDigit:
cmp al, '0'
jb @@IsOperation
;;;;;;;;;;;;
;to enter letters from A to F for hexadecimal notation
cmp al, '9'+1
jb @@1
cmp al, 'A'
jb @@IsOperation
cmp al, 'F'
ja @@IsOperation
mov dl, al
mov ah, 0
sub al, 37h
jmp @@2
;;;;;;;;;;;;
@@1:mov dl, al
mov ah, 0
sub al, '0'
@@2:cmp ax, [Base]
jae @@GetCmd
push ax
mov ah, 02h
int 21h
pop ax
mov [EnBaseChange], 0
mov bx, 0
mov bl, al
mov ax, [Operand2]
mul [Base]
add ax, bx
mov [Operand2], ax
jmp @@GetCmd
@@IsOperation:
cmp al, 'a'
jb @@case
cmp al, 'z'
ja @@case
add al, 'A'-'a'
@@case:
cmp al, 0Dh
jne @@IsBase2
mov al, '='
@@IsBase2:
cmp al, 'B'
jne @@IsBase16
cmp [EnBaseChange], 1
jne @@GetCmd
mov [Base], 2
mov ah, 09h
lea dx, [msgChangeBase2]
int 21h
jmp @@GetCmd
;;;;;;;;;;;;;;;;;;;
@@IsBase16:
cmp al, 'H'
jne @@IsBase10
cmp [EnBaseChange], 1
jne @@GetCmd
mov [Base], 16
mov ah, 09h
lea dx, [msgChangeBase16]
int 21h
jmp @@GetCmd
;;;;;;;;;;;;;;;;;;;
@@IsBase10:
cmp al, 'D'
jne @@IsOp
cmp [EnBaseChange], 1
jne @@GetCmd
mov [Base], 10
mov ah, 09h
lea dx, [msgChangeBase10]
int 21h
jmp @@GetCmd
@@IsOp:
cmp al, OpAdd
je @@DoOperation
cmp al, OpSub
je @@DoOperation
cmp al, OpMul
je @@DoOperation
cmp al, OpDiv
je @@DoOperation
cmp al, '='
je @@DoOperation
jmp @@GetCmd
@@DoOperation:
mov [OperationNext], al
mov ax, [Operand1]
cwd
mov bx, [Operand2]
cmp [Operation], OpAdd
jne @@Sub
add ax, bx
jmp @@Calc
@@Sub:
cmp [Operation], OpSub
jne @@Mul
sub ax, bx
jmp @@Calc
@@Mul:
cmp [Operation], OpMul
jne @@Div
imul bx
@@Div:
cmp [Operation], OpDiv
jne @@Calc
idiv bx
@@Calc:
mov [EnBaseChange], 1
mov [Operand1], ax
mov [Operand2], 0
mov al, [OperationNext]
mov [Operation], al
int 29h
mov ah, 09h
lea dx, [msgBase2]
cmp [Base], 2
mov ah, 09h
lea dx, [msgBase16]
cmp [Base], 16
je @@ShowBase
lea dx, [msgBase10]
@@ShowBase:
int 21h
mov al, [Operation]
cmp al, '='
je @@Break
jmp @@GetCmd
@@Break:
mov ax, [Operand1]
mov bx, [Base]
call ShowUInt16
mov ah, 09h
lea dx, [msgPressAnyKey]
int 21h
mov ah, 00h
int 16h
int 20h
main endp
ShowUInt16 proc
push ax
push bx
push cx
push dx
;mov bx, 10
mov cx, 0
@@div:
xor dx, dx
div bx
add dl, '0'
push dx
inc cx
test ax, ax
jnz @@div
@@show:
mov ah, 02h
pop dx
int 21h
loop @@show
pop dx
pop cx
pop bx
pop ax
ret
ShowUInt16 endp
end main
