A minimum setup to reproduce what seems like a bug in the VMEmulator around static variables in Sys.jack
When assigning a value to static variables within Sys.init(), the assignments clobber other classes' statics
Compiling and running these files demonstrates the issue - 333 gets written to RAM[16] by Keyboard.init, before being overwritten by Sys.init() When Sys.init() calls Sys.static_test() it doesn't overwrite but instead writes to the (seemingly correct) address (RAM[17])
My assumption is that the emulator does not consider Sys.init to be a true Class function that really "belongs" to the Sys class, it is just where the emulation begins directly. Because of this some "currently being compiled/executed Class" variable is not being assigned, so references to static do not know which class's static table they should be looking up, and just default to the top of the static area.