diff --git a/hal/instructions.go b/hal/instructions.go
index 3e43777..4aa198e 100644
--- a/hal/instructions.go
+++ b/hal/instructions.go
@@ -1,6 +1,7 @@
 package hal
 
 import (
+	"fmt"
 	"strings"
 )
 
@@ -9,20 +10,20 @@ type ProgrammedInstruction struct {
 	Operand     float64
 }
 
-func (pi *ProgrammedInstruction) Execute(module *Module) {
+func (pi *ProgrammedInstruction) Execute(module *Module) error {
 	if pi.Instruction.ExecuteWithOperand != nil {
-		pi.Instruction.ExecuteWithOperand(module, pi.Operand)
+		return pi.Instruction.ExecuteWithOperand(module, pi.Operand)
 	} else if pi.Instruction.Execute != nil {
-		pi.Instruction.Execute(module)
+		return pi.Instruction.Execute(module)
 	} else {
-		panic("instruction is not implemented")
+		return fmt.Errorf("instruction is not implemented")
 	}
 }
 
 type Instruction struct {
 	Name               string
-	ExecuteWithOperand func(module *Module, operand float64)
-	Execute            func(module *Module)
+	ExecuteWithOperand func(module *Module, operand float64) error
+	Execute            func(module *Module) error
 }
 
 func FindInstructionByName(name string) *Instruction {
@@ -43,29 +44,87 @@ var instructions = []*Instruction{
 
 var InstructionStart = &Instruction{
 	Name: "START",
-	Execute: func(module *Module) {
+	Execute: func(module *Module) error {
 		// actually not required
 		module.isStopped = false
+		return nil
 	},
 }
 
 var InstructionStop = &Instruction{
 	Name: "STOP",
-	Execute: func(module *Module) {
+	Execute: func(module *Module) error {
 		module.isStopped = true
+		return nil
 	},
 }
 
 var InstructionOut = &Instruction{
 	Name: "OUT",
-	ExecuteWithOperand: func(module *Module, operand float64) {
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		index := int(operand)
+		if len(module.IO) >= index {
+			return fmt.Errorf("index %d exceeds IO size of %d", index, len(module.IO))
+		}
 		module.IO[int64(operand)] = module.accumulator
+		return nil
 	},
 }
 
 var InstructionIn = &Instruction{
 	Name: "IN",
-	Execute: func(module *Module) {
-		// TODO implement
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		index := int(operand)
+		if len(module.IO) >= index {
+			return fmt.Errorf("index %d exceeds IO size of %d", index, len(module.IO))
+		}
+		module.accumulator = module.IO[index]
+		return nil
+	},
+}
+
+var InstructionLoad = &Instruction{
+	Name: "LOAD",
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		index := int(operand)
+		if len(module.register) >= index {
+			return fmt.Errorf("index %d exceeds register size of %d", index, len(module.IO))
+		}
+		module.accumulator = module.register[index]
+		return nil
+	},
+}
+
+var InstructionLoadNum = &Instruction{
+	Name: "LOADNUM",
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		module.accumulator = operand
+		return nil
+	},
+}
+
+var InstructionStore = &Instruction{
+	Name: "STORE",
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		index := int(operand)
+		if len(module.register) >= index {
+			return fmt.Errorf("index %d exceeds register size of %d", index, len(module.IO))
+		}
+		module.register[index] = module.accumulator
+		return nil
+	},
+}
+
+var InstructionJumpNeg = &Instruction{
+	Name: "JUMPNEG",
+	ExecuteWithOperand: func(module *Module, operand float64) error {
+		index := int64(operand)
+		if _, ok := module.programStorage[index]; !ok {
+			return fmt.Errorf("index %d does not exist in program storage", index)
+		}
+		if module.accumulator < 0 {
+			return module.setProgramCounter(index)
+		}
+		return nil
 	},
 }
diff --git a/hal/module.go b/hal/module.go
index 04b1db8..f8597d4 100644
--- a/hal/module.go
+++ b/hal/module.go
@@ -14,16 +14,23 @@ type Module struct {
 	isStopped      bool
 }
 
-func (h *Module) ProgramCounter() int64 {
+func (h *Module) programCounter() int64 {
 	return int64(h.register[0])
 }
+func (h *Module) setProgramCounter(counter int64) error {
+	h.register[0] = float64(counter)
+	if _, ok := h.programStorage[counter]; !ok {
+		return fmt.Errorf("index %d does not exist in program storage", counter)
+	}
+	return nil
+}
 
 func (h *Module) increaseProgramCounter() {
 	h.register[0]++
 }
 
 func (h *Module) Step() {
-	instruction := h.programStorage[h.ProgramCounter()]
+	instruction := h.programStorage[h.programCounter()]
 	h.increaseProgramCounter()
 	if instruction == nil {
 		return
@@ -32,10 +39,10 @@ func (h *Module) Step() {
 }
 
 func (h *Module) Run() error {
-	for !h.isStopped && h.ProgramCounter() <= maxInstructions {
+	for !h.isStopped && h.programCounter() <= maxInstructions {
 		h.Step()
 	}
-	if h.ProgramCounter() > maxInstructions {
+	if h.programCounter() > maxInstructions {
 		return fmt.Errorf("module exceeded max instructions without being stopped")
 	}
 	return nil