The list of supported instructions is very well-documented, so generally it isn't a problem to find information about any bytecode of interest. Here are some examples of what they look like:
Mnemonic | Opcode in hex | Description |
aload | 0x19 | Load reference from a local variable on the stack |
fadd | 0x62 | Add float |
lcmp | 0x94 | Compare long |
Interestingly enough, there are other projects that can produce Java bytecode, for example, JPython, which aims to compile Python files into Java-style bytecode.