diff --git a/riscemu/CPU.py b/riscemu/CPU.py
index 7de1aa0..429341c 100644
--- a/riscemu/CPU.py
+++ b/riscemu/CPU.py
@@ -35,19 +35,19 @@ class CPU:
         self.instruction_sets: List['InstructionSet'] = list()
         self.instructions: Dict[str, Callable[[LoadedInstruction], None]] = dict()
         for set_class in instruction_sets:
-            ins_set = set_class()
-            self.instructions.update(ins_set.load(self))
+            ins_set = set_class(self)
+            self.instructions.update(ins_set.load())
             self.instruction_sets.append(ins_set)
 
         # provide global syscall symbols if option is set
         if conf.include_scall_symbols:
             self.mmu.global_symbols.update(self.syscall_int.get_syscall_symbols())
 
-    def get_tokenizer(self, input):
+    def get_tokenizer(self, tokenizer_input):
         """
         Returns a tokenizer that respects the language of the CPU
         """
-        return RiscVTokenizer(input, self.all_instructions())
+        return RiscVTokenizer(tokenizer_input, self.all_instructions())
 
     def load(self, e: 'Executable'):
         """
@@ -93,23 +93,6 @@ class CPU:
             # this should never be reached, as unknown instructions are imparseable
             raise RuntimeError("Unknown instruction: {}".format(ins))
 
-    def parse_mem_ins(self, ins: 'LoadedInstruction') -> Tuple[str, int]:
-        """
-        parses both rd, rs1, imm and rd, imm(rs1) arguments and returns (rd, imm+rs1)
-        (so a register and address tuple for memory instructions)
-        """
-        if len(ins.args) == 3:
-            # handle rd, rs1, imm
-            rs1 = ins.get_reg(1)
-            imm = ins.get_imm(2)
-        else:
-            ASSERT_LEN(ins.args, 2)
-            ASSERT_IN("(", ins.args[1])
-            imm, rs1 = ins.get_imm_reg(1)
-            # handle rd, imm(rs1)
-        rd = ins.get_reg(0)
-        return rd, self.regs.get(rs1) + imm
-
     def all_instructions(self) -> List[str]:
         return list(self.instructions.keys())
 
diff --git a/riscemu/instructions/InstructionSet.py b/riscemu/instructions/InstructionSet.py
index e52b453..5f7e6ea 100644
--- a/riscemu/instructions/InstructionSet.py
+++ b/riscemu/instructions/InstructionSet.py
@@ -8,16 +8,19 @@ class InstructionSet(ABC):
     """
     Represents a collection of instructions
     """
-    def __init__(self):
-        self.cpu: typing.Optional['CPU'] = None
-        self.mmu: typing.Optional['MMU'] = None
-        self.regs: typing.Optional['Registers'] = None
 
-    def load(self, cpu: 'CPU'):
+    def __init__(self, cpu: 'CPU'):
         self.cpu = cpu
         self.mmu = cpu.mmu
         self.regs = cpu.regs
 
+    def load(self) -> typing.Dict[str, typing.Callable[['LoadedInstruction'], None]]:
+        """
+        This is called by the CPU once it instantiates this instruction set
+
+        It returns a dictionary of all instructions in this instruction set,
+        pointing to the correct handler for it
+        """
         return {
             name: ins for name, ins in self.get_instructions()
         }
@@ -27,24 +30,46 @@ class InstructionSet(ABC):
             if member.startswith('instruction_'):
                 yield member[12:].replace('_', '.'), getattr(self, member)
 
-    def parse_mem_ins(self, ins: 'LoadedInstruction'):
-        return self.cpu.parse_mem_ins(ins)
+    def parse_mem_ins(self, ins: 'LoadedInstruction') -> Tuple[str, int]:
+        """
+        parses both rd, rs, imm and rd, imm(rs) arguments and returns (rd, imm+rs1)
+        (so a register and address tuple for memory instructions)
+        """
+        if len(ins.args) == 3:
+            # handle rd, rs1, imm
+            rs = self.get_reg_content(ins, 1)
+            imm = ins.get_imm(2)
+        else:
+            # handle rd, imm(rs1)
+            ASSERT_LEN(ins.args, 2)
+            ASSERT_IN("(", ins.args[1])
+            imm, rs_name = ins.get_imm_reg(1)
+            rs = self.regs.get(rs_name)
+        rd = ins.get_reg(0)
+        return rd, rs + imm
 
-    def parse_rd_rs_rs(self, ins: 'LoadedInstruction'):
+    def parse_rd_rs_rs(self, ins: 'LoadedInstruction') -> Tuple[str, int, int]:
+        """
+        Assumes the command is in <name> rd, rs1, rs2 format
+        Returns the name of rd, and the values in rs1 and rs2
+        """
         ASSERT_LEN(ins.args, 3)
         return ins.get_reg(0), self.get_reg_content(ins, 1), self.get_reg_content(ins, 2)
 
-    def parse_rd_rs_imm(self, ins: 'LoadedInstruction'):
+    def parse_rd_rs_imm(self, ins: 'LoadedInstruction') -> Tuple[str, int, int]:
+        """
+        Assumes the command is in <name> rd, rs, imm format
+        Returns the name of rd, the value in rs and the immediate imm
+        """
         ASSERT_LEN(ins.args, 3)
         return ins.get_reg(0), self.get_reg_content(ins, 1), ins.get_imm(2)
 
-    def get_reg_content(self, ins: 'LoadedInstruction', ind: int):
+    def get_reg_content(self, ins: 'LoadedInstruction', ind: int) -> int:
         """
         get the register name from ins and then return the register contents
         """
         return self.regs.get(ins.get_reg(ind))
 
-
     @property
     def pc(self):
         return self.cpu.pc
@@ -57,4 +82,4 @@ class InstructionSet(ABC):
         return "InstructionSet[{}] with {} instructions".format(
             self.__class__.__name__,
             len(list(self.get_instructions()))
-        )
\ No newline at end of file
+        )