Initial VIC-20 emulator based on C64 source

README.md

@@ -25,3 +25,7 @@ The C64 Emulator uses a symbolic keyboard translation thus any keyboard layout s
 
 This C64 emulator is just a a very basic 6502/6510 emulation example and is not feature complete. Please take a look at [VICE - Versatile Commodore Emulator](http://vice-emu.sourceforge.net/) instead.
 
+# VIC-20 emulator
+
+Based on the C64 emulator, a VIC-20 emulator is now included. You need to download the BASIC ROM [basic.901486-01.bin](http://www.commodore.ca/manuals/funet/cbm/firmware/computers/vic20/basic.901486-01.bin) and the Kernal ROM [kernal.901486-07.bin](http://www.commodore.ca/manuals/funet/cbm/firmware/computers/vic20/kernal.901486-07.bin) and put both files inside the ROMs folder. Changes compared to the C64 source are Addr and Keyboard matrix.
+

VIC-20/ROMs/README.md

@@ -0,0 +1 @@
+Put your BASIC and Kernal ROMs here

VIC-20/Source/FormV20.dfm

@@ -0,0 +1,23 @@
+object FrmVC20: TFrmVC20
+  Left = 0
+  Top = 0
+  BorderStyle = bsDialog
+  Caption = 'VIC-20 Emu'
+  ClientHeight = 393
+  ClientWidth = 645
+  Color = clBtnFace
+  Font.Charset = DEFAULT_CHARSET
+  Font.Color = clWindowText
+  Font.Height = -11
+  Font.Name = 'Tahoma'
+  Font.Style = []
+  KeyPreview = True
+  OldCreateOrder = False
+  Position = poScreenCenter
+  OnCreate = FormCreate
+  OnDestroy = FormDestroy
+  OnKeyPress = FormKeyPress
+  OnKeyUp = FormKeyUp
+  PixelsPerInch = 96
+  TextHeight = 13
+end

VIC-20/Source/FormV20.pas

@@ -0,0 +1,96 @@
+unit FormV20;
+
+interface
+
+uses
+  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
+  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, VIC20, Vcl.StdCtrls, Vcl.ExtCtrls;
+
+const
+  ScreenZoom = 2;
+  ScreenWidth = 176 * ScreenZoom;   // 320
+  ScreenHeight = 184 * ScreenZoom;  // 200
+
+  ColorTable: array [0 .. 2] of Cardinal = ($801010, $D0A0A0, $D0A0A0);
+
+type
+  TFrmVC20 = class(TForm)
+    procedure FormCreate(Sender: TObject);
+    procedure FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
+    procedure FormKeyPress(Sender: TObject; var Key: Char);
+    procedure FormDestroy(Sender: TObject);
+  private
+    { Private declarations }
+    procedure OnScreenWrite(var Msg: TMessage); message WM_SCREEN_WRITE;
+  public
+    { Public declarations }
+    LastKey: Char;
+    VC20: TVC20;
+  end;
+
+var
+  FrmVC20: TFrmVC20;
+
+implementation
+
+{$R *.dfm}
+
+procedure TFrmVC20.FormCreate(Sender: TObject);
+begin
+  ClientWidth := ScreenWidth;
+  ClientHeight := ScreenHeight;
+
+  Canvas.Font.Name := 'cbm';
+  Canvas.Font.Height := 8 * ScreenZoom;
+  Canvas.Brush.Style := bsSolid;
+
+  VC20 := TVC20.Create;
+  VC20.WndHandle := Handle;
+  VC20.LoadROM('..\ROMs\kernal.901486-06.bin', $E000); // E000-FFFF
+  VC20.LoadROM('..\ROMs\basic.901486-01.bin', $C000); // C000-DFFF
+  VC20.Exec;
+end;
+
+procedure TFrmVC20.FormDestroy(Sender: TObject);
+begin
+  VC20.Free;
+end;
+
+procedure TFrmVC20.FormKeyPress(Sender: TObject; var Key: Char);
+begin
+  VC20.SetKey(Key, 1);
+  LastKey := Key;
+end;
+
+procedure TFrmVC20.FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
+begin
+  if LastKey <> #0 then
+    VC20.SetKey(LastKey, 0);
+  LastKey := #0;
+end;
+
+procedure TFrmVC20.OnScreenWrite(var Msg: TMessage);
+var
+  Addr: Word;
+  Value: Integer;
+  X, Y: Integer;
+  Flag: Cardinal;
+  Q1: Byte;
+  Sc: Char;
+begin
+  Addr := Msg.WParam;
+  Value := Msg.LParam;
+
+  Y := (Addr div 22); //40
+  X := (Addr - Y*22); //40
+
+  Flag := (Value shr 7) and $FF;
+  Q1 := Value and $7F;
+  Sc := Char((Q1 + 32 * (ord(Q1 < 32) * 2 + ord(Q1 > 63) + ord(Q1 > 95))));
+
+  Canvas.Font.Color := ColorTable[1 - Flag];
+  Canvas.Brush.Color := ColorTable[Flag];
+  Canvas.TextOut(X * (8*ScreenZoom), Y * (8*ScreenZoom), Sc);
+end;
+
+end.

VIC-20/Source/VIC20.pas

@@ -0,0 +1,212 @@
+unit VIC20;
+
+interface
+
+uses
+  System.Classes, WinApi.Messages, MOS6502;
+
+const
+  WM_SCREEN_WRITE = WM_USER + 0;
+
+  CIA1 = $9120;   // $DC00;
+
+  // VIC-20 keyboard matrix
+  KEY_TRANSLATION = '2q'#0' '#27#0#0'1'+
+                    '4esz'#0'aw3'+
+                    '6tfcxdr5'+
+                    '8uhbvgy7'+
+                    '0okmnji9'+
+                    '-@:.,lp+'+
+                    #0#0'='#0'/;*£'+
+                    #0#0#0#0#0#0#13#8+
+
+                    '"'#0#0#0#0#0#0'!'+
+                    '$'#0#0#0#0#0#0'#'+
+                    '&'#0#0#0#0#0#0'%'+
+                    '('#0#0#0#0#0#0''''+
+                    '0'#0#0#0#0#0#0')'+
+                    '_'#0'[><l'#0#0+
+                    #0#0'='#0'?]'#0#0+
+                    #0#0#0#0#0#0#13#8;
+
+type
+  TVC20 = class;
+
+  TVC20Thread = class(TThread)
+  private
+    VC20: TVC20;
+  protected
+  public
+    procedure Execute; override;
+    constructor Create(VC20Instance: TVC20);
+  end;
+
+  TVC20 = class(TMOS6502)
+  private
+    Thread: TVC20Thread;
+    TimerHandle: Integer;
+    LastKey: Char;
+    procedure BusWrite(Adr: Word; Value: Byte);
+    function BusRead(Adr: Word): Byte;
+    function KeyRead: Byte;
+  protected
+    KeyMatrix: Array[0 .. 7, 0 .. 7] of Byte;
+    Memory: PByte;
+    InterruptRequest: Boolean;
+  public
+    WndHandle: THandle;
+    constructor Create;
+    destructor Destroy; override;
+    procedure LoadROM(Filename: String; Addr: Word);
+    procedure Exec;
+    procedure SetKey(Key: Char; Value: Byte);
+  end;
+
+implementation
+
+uses
+  System.SysUtils, Winapi.Windows, WinApi.MMSystem;
+
+{ TVC20 }
+
+procedure TimerProcedure(TimerID, Msg: Uint; dwUser, dw1, dw2: DWORD); pascal;
+var
+  VC20: TVC20;
+begin
+  VC20 := TVC20(dwUser);
+
+  if VC20.Status and VC20.INTERRUPT = 0 then // if IRQ allowed then set irq
+    VC20.InterruptRequest := True;
+end;
+
+
+function TVC20.BusRead(Adr: Word): Byte;
+begin
+  Result := Memory[Adr];
+end;
+
+procedure TVC20.BusWrite(Adr: Word; Value: Byte);
+begin
+  // test for I/O requests
+  case Adr of
+    CIA1:
+      begin
+        // Handle keyboard reading
+        Memory[Adr] := Value;
+        Memory[CIA1 + 1] := KeyRead;
+      end;
+
+    CIA1 + 5: // Timer
+     if TimerHandle = 0 then
+       TimerHandle := TimeSetEvent(34, 2, @TimerProcedure, DWORD(Self), TIME_PERIODIC);
+  end;
+
+  if (Adr >= $2000) then // $A000  // treat anything above as ROM
+    Exit;
+
+  Memory[Adr] := Value;
+
+  // video RAM
+  if (Adr >= $1E00) and (Adr <= $1FF9) then   // $400 - $07E7
+    PostMessage(WndHandle, WM_SCREEN_WRITE, Adr - $1E00, Value);  // $400
+end;
+
+constructor TVC20.Create;
+begin
+  inherited Create(BusRead, BusWrite);
+
+  // create 64kB memory table
+  GetMem(Memory, 65536);
+
+  Thread := TVC20Thread.Create(Self);
+end;
+
+destructor TVC20.Destroy;
+begin
+  if TimerHandle <> 0 then
+    Timekillevent(TimerHandle);
+  Thread.Terminate;
+  Thread.WaitFor;
+  FreeMem(Memory);
+  inherited;
+end;
+
+procedure TVC20.Exec;
+begin
+  Reset;
+  Thread.Start;
+end;
+
+function TVC20.KeyRead: Byte;
+var
+  Row, Col, Cols: Byte;
+begin
+  Result := 0;
+  Cols := Memory[CIA1];
+  for Col := 0 to 7 do
+    if Cols and (1 shl Col) = 0 then  // a 0 indicates a column read
+      for Row := 0 to 7 do
+        if KeyMatrix[7 - Col, Row] = 1 then
+          Result := Result + (1 shl Row);
+  Result := not Result;
+end;
+
+procedure TVC20.LoadROM(Filename: String; Addr: Word);
+var
+  Stream: TFileStream;
+begin
+  Stream := TFileStream.Create(Filename, fmOpenRead);
+  try
+    Stream.Read(Memory[Addr], Stream.Size);
+  finally
+    Stream.Free;
+  end;
+end;
+
+procedure TVC20.SetKey(Key: Char; Value: Byte);
+var
+  KeyPos: Integer;
+begin
+  KeyPos := Pos(Key, KEY_TRANSLATION) - 1;
+  if KeyPos >= 0 then
+  begin
+    // always release last key on keypress
+    if Value = 1 then
+    begin
+      SetKey(LastKey, 0);
+      LastKey := Key;
+    end;
+
+    if KeyPos > 63 then  // set right shift on/off
+    begin
+      KeyMatrix[3, 6] := Value;   // 1, 4
+      Dec(KeyPos, 64);
+    end;
+
+    KeyMatrix[KeyPos mod 8, KeyPos div 8] := Value;
+  end;
+end;
+
+{ TVC20Thread }
+
+constructor TVC20Thread.Create(VC20Instance: TVC20);
+begin
+  inherited Create(True);
+  VC20 := VC20Instance;
+end;
+
+procedure TVC20Thread.Execute;
+begin
+  while (not Terminated) do
+  begin
+    if VC20.InterruptRequest then
+    begin
+      VC20.InterruptRequest := False;
+      VC20.IRQ;
+    end;
+    VC20.Step;
+    Sleep(0);
+  end;
+end;
+
+end.

VIC-20/Source/VIC20Emu.dpr

@@ -0,0 +1,16 @@
+program VIC20Emu;
+
+uses
+  Vcl.Forms,
+  FormV20 in 'FormV20.pas' {FrmVC20},
+  VIC20 in 'VIC20.pas',
+  MOS6502 in '..\..\Source\MOS6502.pas';
+
+{$R *.res}
+
+begin
+  Application.Initialize;
+  Application.MainFormOnTaskbar := True;
+  Application.CreateForm(TFrmVC20, FrmVC20);
+  Application.Run;
+end.