Java processor demo (Microjava)

Description

This applet demonstrates the MicroJava microprocessor (Mic2) from [Tanenbaum, Structured Computer Organization, 2001].

Please wait until the applet is fully loaded. Then press the clock switch a few times to single-step through the machine cycles of the Microjava processor. It first initializes a few registers, then executes a simple program. Use the clock 1/2 switch to select manual clocking (via the clock switch) or automatic clocking.

While the applets includes all required hardware of the Microjava2 processor, at the moment only the following JVM opcodes are implemented in the microcode:

 NOP        (0x00)
 BIPUSH     (0x10)
 IADD       (0x60)
 INIT       (0xFE - implementation specific opcode, here: initialization)

  addr   32-bit data   
  0000   fe002010    
  0001   03100460      
  0002   00000000
  ....
  0020   0001000f
  0021   00010000
  0022   00010100
  ....

  fe 00 20     custom-opcode (initialization from ROM address 0020)
  10 03        bipush 03
  10 04        bipush 04
  60           iadd
  00           nop (actually starts processor initialization again...)
  ...

Therefore, the program first load the value 0x00000003 into TOS and memory address 0x00010010, and next loads the value 0x00000004 into TOS and memory address 0x00010011. It then adds the values and stores the result (0x00000007) into memory address 0x00010010.

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