Simple CPU Simulator with Excel VBA ref: http://qiita.com/kencoba/items/25083937af095358be79

MicroComputer

Option Explicit
Private cPC As Range ' ProgramCounter
Private cCR As Range ' CommandRegister
Private cAR As Range ' AddressRegister
Private cAA As Range ' AccumulatorA
Private cAB As Range ' AccumulatorB

Sub Init()
    Set cPC = Worksheets(1).Cells(2, 4)
    Set cCR = Worksheets(1).Cells(2, 5)
    Set cAR = Worksheets(1).Cells(2, 6)
    Set cAA = Worksheets(1).Cells(2, 7)
    Set cAB = Worksheets(1).Cells(2, 8)
End Sub

Sub ExecuteStep()
    Call Init
    Call ReadOneCommand
    Call IncrementProgramCounter
    Call ExecuteOneCommand
End Sub

Sub ReadOneCommand()
    cCR.Value2 = GetCP
    cAR.Value2 = GetAP
End Sub

Function GetCP()
    GetCP = Worksheets(1).Cells(cPC.Value2 - 98, 2)
End Function

Function GetAP()
    GetAP = Worksheets(1).Cells(cPC.Value2 - 98, 3)
End Function

Sub IncrementProgramCounter()
    cPC.Value2 = cPC.Value2 + 1
End Sub

Sub ExecuteOneCommand()
    Select Case cCR.Value2
        Case "読み込む"
            Call CmdLoad
        Case "加算する"
            Call CmdAdd
        Case "書き込み"
            Call CmdStore
        Case "終了"
            Call CmdExit
    End Select
End Sub

Sub CmdLoad()
    cAA.Value2 = Worksheets(1).Cells(cAR.Value2 - 98, 2)
End Sub

Sub CmdAdd()
    cAB.Value2 = Worksheets(1).Cells(cAR.Value2 - 98, 2)
    cAA.Value2 = cAA.Value2 + cAB.Value2
End Sub

Sub CmdStore()
    Worksheets(1).Cells(cAR.Value2 - 98, 2).Value2 = cAA.Value2
End Sub

Sub CmdExit()
    MsgBox ("Exit")
End Sub