Classic Computer Magazine Archive COMPUTE! ISSUE 46 / MARCH 1984 / PAGE 10

Mysterious Commodore SYS

Our users group, Richmond Area Commodore Enthusiasts, would like to find out all about the SYStem commands. We know that SYS 64802 will cold start the VIC. Is there any publication, book, or article that has a list of all the SYS commands? Our computer manuals give the definition of the SYS command, but other than a few examples, offers nothing further.

E. M. Rexrode

The SYS command is used to transfer control from a BASIC program to a machine language program. The format for the SYS command is SYS NNNNN, where NNNNN is any memory location. The computer will start executing the machine language at the address specified by NNNNN.

SYS is user-controlled. That is, in the VIC and the 64, you can SYS to any memory location between 1 and 65535. The memory location can be the start of a machine language program in user RAM, or an ML routine within BASIC or Kernal ROM. The SYS command is not a prewritten package of routines.

There is only one SYS command, but it can access many routines within the computer (such as "cold start," which simulates turning the computer on). To learn these addresses you need a map of your computer's memory. These maps are found in various COMPUTE! Books such as COMPUTEl's First Book of VIC, Mapping the VIC, Mapping the 64, The 64 Toolkit, and Machine Language for Beginners.