SASM (Simulated Assembly)

• SASM is a simple operating system simulator that reads assembly language and does something.

Interrupts

INT 0x80

• Interrupt 80 is the Interrupt for #Syscalls.
• Usage:

MOV     D, <SyscallNumber>  ; The syscall
INT     0x80                ; The interrupt

Syscalls

0x01 - PUTI

• Put Int, Print a integer in stdout
• A = int
• Usage:

MOV     A, 0x01  ; integer 1
MOV     D, 0x01  ; syscall PUTI
INT     0x80     ; perform syscall

0x02 - PUTC

• Put Char, Print a char in stdout
• A = char
• Returns in A = Bytes writter
• Usage:

MOV     A, 0x0A  ; char A in hexa
MOV     D, 0x02  ; syscall PUTC
INT     0x80     ; perform syscall

0x03 - EXIT

• Exit the program with status code.
• A = status code.
• Usage:

MOV     A, 0x00  ; 0 in hexa
MOV     D, 0x03  ; syscall EXIT
INT     0x80     ; perform syscall