I'm developing an operating system in assembly language.
At a certain time i get this error from NASM:
os.asm:113: error: TIMES value -138 is negative
I want to take this project to the end. Only the errors like that despair me!
Here is the code:
BITS 16
start:
mov ax, 07C0h ; Set up 4K stack space after this bootloader
add ax, 288 ; (4096 + 512) / 16 bytes per paragraph
mov ss, ax
mov sp, 4096
mov ax, 07C0h ; Set data segment to where we're loaded
mov ds, ax
call cls
MOV AH, 06h ; Scroll up function
XOR AL, AL ; Clear entire screen
XOR CX, CX ; Upper left corner CH=row, CL=column
MOV DX, 184FH ; lower right corner DH=row, DL=column
MOV BH, 1Eh ; YellowOnBlue
INT 10H
mov si, text_string ; Put string position into SI
call print_string ; Call our string-printing routine
push bx ;push registers
push cx
push dx
mov ah,0h
int 16h
cmp al, '1'
je reboot
cmp al, '2'
je shutdown
cmp al, '3'
je about
cmp al, '4'
je message
cmp al, '5'
je shutdown
cmp al, '6'
je credits
jmp $ ; Jump here - infinite loop!
text_string db '|Main Menu| |Smile OS V1.4|',13,10,'1) Reboot',13,10,'2) Shutdown',13,10,'3) About',13,10,'4) Message',13,10,'5) System Halt',13,10,'6) Credits',0
about_string db '|About|',13,10,'Smile OS is a console based operating system in assembly language. 8 hours of intense work done by Alex~s Software. Many errors but solved and very successful.',13,10,'Press any key to go back!',0
message_str db '|Message|',10,13,'Hello, World!',13,10,'Press any key to go back!',0
cr_str db '|Credits|',13,10,'Copyright ? 2018 Alex~s Software',13,10,'Main Programer: Alex',13,10,'Graphichs: What graphics?',13,10,'Idea: nobody :)',0
reboot:
mov ax, 0
int 19h
shutdown:
mov ax, 0x1000
mov ax, ss
mov sp, 0xf000
mov ax, 0x5307
mov bx, 0x0001
mov cx, 0x0003
int 0x15
credits:
call cls
mov si, cr_str ; Put string position into SI
call print_string ; Call our string-printing routine
push bx ;push registers
push cx
push dx
mov ah,0h
int 16h
je start
message:
call cls
mov si, message_str ; Put string position into SI
call print_string ; Call our string-printing routine
push bx ;push registers
push cx
push dx
mov ah,0h
int 16h
je start
cls:
pusha
mov ah, 0x00
mov al, 0x03 ; text mode 80x25 16 colours
int 0x10
popa
ret
about:
call cls
mov si, about_string ; Put string position into SI
call print_string ; Call our string-printing routine
push bx ;push registers
push cx
push dx
mov ah,0h
int 16h
je start
print_string: ; Routine: output string in SI to screen
mov ah, 0Eh ; int 10h 'print char' function
.repeat:
lodsb ; Get character from string
cmp al, 0
je .done ; If char is zero, end of string
int 10h ; Otherwise, print it
jmp .repeat
.done:
ret
times 512 - ($ - $$) db 0
signature dw 0xaa55
Why Times value is negative? Hhy others do not get the same error? (Or like that)
I use this :
NASM version 2.14
Oracle VM VirtualBox version 6.0.0_RC1
rawwrite dd for windows version 0.5.
For compile:
nasm os.asm -f bin -o os.bin
dd if=/dev/zero of=os.img bs=1024 count=1440
dd if=os.bin of=os.img
See Question&Answers more detail:
os 
