====== SYS ======

[pet] [vic20] [c64] [c16] [cplus4] [c128] [x16] [m65]

The ''SYS'' commands calls a machine language subroutine at the specified address.

===== Syntax =====

  SYS <address> [FAST]

If used without the ''FAST'' directive, ''SYS'' will do the same as in CBM BASIC, that is, it will load the accumulator, the X and the Y register, and the status register from addresses $030C-$030F (on C64 and VIC-20) or $07F2-$07F5 (on CPlus/4 and C16) before the call. When the subroutine exits, ''SYS'' will save the values of these registers to the same memory addresses.

If however it is used with the ''FAST'' directive, a simpler and faster procedure is taken: the program will just jump to the specified address, without loading and saving the registers before and after the call.

<adm note>
Use the ''FAST'' directive if you don't need to pass values in registers to the subroutine.
</adm>

===== Examples =====

  SYS $C000 FAST : REM calls a subroutine at $C000 without passing registers
  SYS 64738 FAST : REM restarts the machine
  
  REM -- Printing a character on screen using the KERNAL function CHROUT
  CONST CHROUT =  $FFD2
  CONST ACCU = $030C ' C64 and VIC-20 only
  POKE ACCU, 'A': REM to load accumulator with the PETSCII code of 'A'
  SYS CHROUT : REM will output "A"