diff --git a/README.md b/README.md
index 004fc98..06ead2d 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@ An Apple //e emulator written in Go using [ebiten](https://github.com/hajimehosh
 * MOS 6502 CPU
 * Keyboard
 * 40 column text mode
-* Low resolution color graphics
-* High resolution monochrome graphics
+* Low resolution monochrome and color graphics
+* High resolution monochrome and color graphics
 * Upper memory bank switching: $d000 page and ROM/RAM
 * Main memory page1/page2 switching in text, lores and hires
 * Disk image reading & writing
@@ -34,7 +34,7 @@ Download `apple2e.rom` from
 ## Keyboard shortcuts
 
 * ctrl-alt-R reset
-* ctrl-alt-M mute
+* ctrl-alt-M toggle monochrome/color display
 * ctrl-alt-C caps lock
 * ctrl-alt-F show FPS
 
diff --git a/apple2.go b/apple2.go
index 920b396..fc406f1 100644
--- a/apple2.go
+++ b/apple2.go
@@ -26,8 +26,9 @@ var (
 	disableDosDelay     *bool   // Disable DOS delay functions
 	breakAddress        *uint16 // Break address from the command line
 
-	resetKeysDown bool // Keep track of ctrl-alt-R key down state
-	fpsKeysDown   bool // Keep track of ctrl-alt-F key down state
+	resetKeysDown      bool // Keep track of ctrl-alt-R key down state
+	fpsKeysDown        bool // Keep track of ctrl-alt-F key down state
+	monochromeKeysDown bool // Keep track of ctrl-alt-M key down state
 )
 
 // checkSpecialKeys checks
@@ -53,14 +54,27 @@ func checkSpecialKeys() {
 	} else {
 		fpsKeysDown = false
 	}
+
+	// Check for ctrl-alt-M and toggle FPS display
+	if ebiten.IsKeyPressed(ebiten.KeyControl) && ebiten.IsKeyPressed(ebiten.KeyAlt) && ebiten.IsKeyPressed(ebiten.KeyM) {
+		monochromeKeysDown = true
+	} else if ebiten.IsKeyPressed(ebiten.KeyControl) && ebiten.IsKeyPressed(ebiten.KeyAlt) && !ebiten.IsKeyPressed(ebiten.KeyM) && monochromeKeysDown {
+		monochromeKeysDown = false
+		video.Monochrome = !video.Monochrome
+	} else {
+		monochromeKeysDown = false
+	}
 }
 
 // update is the main ebiten loop
 func update(screen *ebiten.Image) error {
 
-	keyboard.Poll()    // Convert ebiten's keyboard state to an interal value
 	checkSpecialKeys() // Poll the keyboard and check for R and F keys
 
+	if !(fpsKeysDown || monochromeKeysDown) {
+		keyboard.Poll() // Convert ebiten's keyboard state to an interal value
+	}
+
 	system.FrameCycles = 0     // Reset cycles processed this frame
 	system.LastAudioCycles = 0 // Reset processed audio cycles
 	exitAtBreak := true        // Die if a BRK instruction is seen
@@ -122,7 +136,7 @@ func main() {
 
 	// Start the ebiten main loop
 	ebiten.SetRunnableInBackground(true)
-	ebiten.Run(update, 280*video.ScreenSizeFactor, 192*video.ScreenSizeFactor, 2, "Apple //e")
+	ebiten.Run(update, 560, 384, 1, "Apple //e")
 
 	// The main loop has ended, flush any data to the disk image if any writes have been done.
 	disk.FlushImage()
diff --git a/video/video.go b/video/video.go
index 4f87c80..30a43b1 100644
--- a/video/video.go
+++ b/video/video.go
@@ -12,9 +12,6 @@ import (
 )
 
 const (
-	// ScreenSizeFactor is the fFactor by which the whole screen is resized
-	ScreenSizeFactor = 1
-
 	textVideoMemory = 0x400 // Base location of page 1 text video memory
 	flashFrames     = 11    // Number of frames when FLASH mode is toggled
 )
@@ -23,19 +20,27 @@ const (
 type drawTextLoresByte func(*ebiten.Image, int, int, uint8) error
 
 var (
-	flashCounter int               // Counter used for flashing characters on the text screen
-	flashOn      bool              // Are we currently flashing?
-	loresSquares [16]*ebiten.Image // Colored blocks for lores rendering
+	flashCounter           int               // Counter used for flashing characters on the text screen
+	flashOn                bool              // Are we currently flashing?
+	monochromeLoresSquares [16]*ebiten.Image // Monochrome blocks for lores rendering
+	colorLoresSquares      [16]*ebiten.Image // Colored blocks for lores rendering
+	colors                 [16]color.NRGBA   // 4-bit Colors
 
 	// ShowFPS determines if the FPS is shown in the corner of the video
-	ShowFPS bool
+	ShowFPS    bool
+	Monochrome bool
 )
 
 // initLoresSquares creates 16 colored squares for the lores renderer
 func initLoresSquares() {
 	var err error
 	for i := 0; i < 16; i++ {
-		loresSquares[i], err = ebiten.NewImage(7, 4, ebiten.FilterNearest)
+		monochromeLoresSquares[i], err = ebiten.NewImage(7, 4, ebiten.FilterNearest)
+		if err != nil {
+			panic(err)
+		}
+
+		colorLoresSquares[i], err = ebiten.NewImage(7, 4, ebiten.FilterNearest)
 		if err != nil {
 			panic(err)
 		}
@@ -45,27 +50,36 @@ func initLoresSquares() {
 	// https://mrob.com/pub/xgithub.com/freewilll/apple2/colors.html
 	// https://archive.org/details/IIgs_2523063_Master_Color_Values
 	alpha := uint8(0xff)
-	loresSquares[0x00].Fill(color.NRGBA{0, 0, 0, alpha})
-	loresSquares[0x01].Fill(color.NRGBA{221, 0, 51, alpha})
-	loresSquares[0x02].Fill(color.NRGBA{0, 0, 153, alpha})
-	loresSquares[0x03].Fill(color.NRGBA{221, 34, 221, alpha})
-	loresSquares[0x04].Fill(color.NRGBA{0, 119, 34, alpha})
-	loresSquares[0x05].Fill(color.NRGBA{85, 85, 85, alpha})
-	loresSquares[0x06].Fill(color.NRGBA{34, 34, 255, alpha})
-	loresSquares[0x07].Fill(color.NRGBA{102, 170, 255, alpha})
-	loresSquares[0x08].Fill(color.NRGBA{136, 85, 0, alpha})
-	loresSquares[0x09].Fill(color.NRGBA{255, 102, 0, alpha})
-	loresSquares[0x0A].Fill(color.NRGBA{170, 170, 170, alpha})
-	loresSquares[0x0B].Fill(color.NRGBA{255, 153, 136, alpha})
-	loresSquares[0x0C].Fill(color.NRGBA{17, 221, 0, alpha})
-	loresSquares[0x0D].Fill(color.NRGBA{255, 255, 0, alpha})
-	loresSquares[0x0E].Fill(color.NRGBA{68, 255, 153, alpha})
-	loresSquares[0x0F].Fill(color.NRGBA{255, 255, 255, alpha})
+
+	colors[0x00] = color.NRGBA{0, 0, 0, alpha}
+	colors[0x01] = color.NRGBA{221, 0, 51, alpha}
+	colors[0x02] = color.NRGBA{0, 0, 153, alpha}
+	colors[0x03] = color.NRGBA{221, 34, 221, alpha}
+	colors[0x04] = color.NRGBA{0, 119, 34, alpha}
+	colors[0x05] = color.NRGBA{85, 85, 85, alpha}
+	colors[0x06] = color.NRGBA{34, 34, 255, alpha}
+	colors[0x07] = color.NRGBA{102, 170, 255, alpha}
+	colors[0x08] = color.NRGBA{136, 85, 0, alpha}
+	colors[0x09] = color.NRGBA{255, 102, 0, alpha}
+	colors[0x0A] = color.NRGBA{170, 170, 170, alpha}
+	colors[0x0B] = color.NRGBA{255, 153, 136, alpha}
+	colors[0x0C] = color.NRGBA{17, 221, 0, alpha}
+	colors[0x0D] = color.NRGBA{255, 255, 0, alpha}
+	colors[0x0E] = color.NRGBA{68, 255, 153, alpha}
+	colors[0x0F] = color.NRGBA{255, 255, 255, alpha}
+
+	for i := 0; i < 0x10; i++ {
+		colorLoresSquares[i].Fill(colors[i])
+		avgIntensity := float64(int(colors[i].R)+int(colors[i].G)+int(colors[i].B)) / 3
+		avgColor := color.NRGBA{byte(avgIntensity * 0.2), byte(avgIntensity * 0.75), byte(avgIntensity * 0.2), alpha}
+		monochromeLoresSquares[i].Fill(avgColor)
+	}
 }
 
 // Init the video data structures used for rendering
 func Init() {
 	ShowFPS = false
+	Monochrome = true
 
 	initTextCharMap()
 	initLoresSquares()
@@ -95,8 +109,8 @@ func drawText(screen *ebiten.Image, x int, y int, value uint8) error {
 	}
 
 	op := &ebiten.DrawImageOptions{}
-	op.GeoM.Scale(ScreenSizeFactor, ScreenSizeFactor)
-	op.GeoM.Translate(ScreenSizeFactor*7*float64(x), ScreenSizeFactor*8*float64(y))
+	op.GeoM.Scale(2, 2)
+	op.GeoM.Translate(2*7*float64(x), 2*8*float64(y))
 
 	r := image.Rect(0, 0, 7, 8)
 	op.SourceRect = &r
@@ -107,8 +121,10 @@ func drawText(screen *ebiten.Image, x int, y int, value uint8) error {
 		op.ColorM.Translate(1, 1, 1, 0)
 	}
 
-	// Make it look greenish
-	op.ColorM.Scale(0.20, 0.75, 0.20, 1)
+	if Monochrome {
+		// Make it look greenish
+		op.ColorM.Scale(0.20, 0.75, 0.20, 1)
+	}
 
 	return screen.DrawImage(charMap[value], op)
 }
@@ -121,9 +137,17 @@ func drawLores(screen *ebiten.Image, x int, y int, value uint8) error {
 	// Render top & bottom squares
 	for i := 0; i < 2; i++ {
 		op := &ebiten.DrawImageOptions{}
-		op.GeoM.Scale(ScreenSizeFactor, ScreenSizeFactor)
-		op.GeoM.Translate(ScreenSizeFactor*7*float64(x), ScreenSizeFactor*8*float64(y)+float64(i)*4)
-		if err := screen.DrawImage(loresSquares[values[i]], op); err != nil {
+		op.GeoM.Scale(2, 2)
+		op.GeoM.Translate(2*7*float64(x), 2*8*float64(y)+2*float64(i)*4)
+
+		var loresSquare *ebiten.Image
+		if Monochrome {
+			loresSquare = monochromeLoresSquares[values[i]]
+		} else {
+			loresSquare = colorLoresSquares[values[i]]
+		}
+
+		if err := screen.DrawImage(loresSquare, op); err != nil {
 			return err
 		}
 	}
@@ -187,11 +211,8 @@ func drawTextOrLoresScreen(screen *ebiten.Image) error {
 
 // drawHiresScreen draws an entire hires screen. If it's in mixed mode, the lower end is drawn in text.
 func drawHiresScreen(screen *ebiten.Image) error {
-	if ScreenSizeFactor != 1 {
-		panic("Hires mode for ScreenSizeFactor != 1 not implemented")
-	}
-
-	pixels := make([]byte, 280*192*4)
+	pixels := make([]byte, 560*384*4)
+	halfPixels := make([]byte, 14)
 
 	// Loop over all hires lines
 	for y := 0; y < 192; y++ {
@@ -207,21 +228,65 @@ func drawHiresScreen(screen *ebiten.Image) error {
 			yOffset += 0x2000
 		}
 
-		// For each byte, flip the 7 bits and write it to the pixels array
+		// Initialize 4-bit 4-color and 14 half-pixels
+		var color uint8      // Current 4-bit color
+		colorPos := uint8(0) // Current half-pixel in the 4-bit color
+		for i := 0; i < 14; i++ {
+			halfPixels[i] = 0
+		}
+
+		// For each byte, expand the 7 bits to the 14 half-pixels array
+		// If the high bit is set, shift one half pixel over.
+		// Don't shift half-bits in monochrome mode
 		for x := 0; x < 40; x++ {
 			offset := yOffset + x
 			value := mmu.ReadPageTable[offset>>8][offset&0xff]
-			value &= 0x7f
 
+			phaseShifted := value >> 7
+
+			var hp uint8
+			if Monochrome {
+				hp = 0
+			} else {
+				hp = phaseShifted
+			}
+
+			halfPixels[0] = halfPixels[13] // Rotate the last phase shifted pixel in
+
+			// Double up the pixels into half pixels starting at offset hp
 			for bit := 0; bit < 7; bit++ {
-				b := float64(value & 1)
+				halfPixels[hp] = value & 1
+				hp = hp + 1
+				if hp < 14 {
+					halfPixels[hp] = value & 1
+					hp = hp + 1
+				}
 				value = value >> 1
-				p := (y*280 + x*7 + bit) * 4
+			}
 
-				pixels[p+0] = byte(0xff * float64(0.20) * b)
-				pixels[p+1] = byte(0xff * float64(0.75) * b)
-				pixels[p+2] = byte(0xff * float64(0.20) * b)
-				pixels[p+3] = 0xff
+			for hp = 0; hp < 14; hp++ {
+				// Update the color bit in colorPos with the half pixel value
+				color &= ((1 << colorPos) ^ 0xf)
+				color |= halfPixels[hp] << colorPos
+				colorPos = (colorPos + 1) & 3
+
+				// Draw two lines at a time
+				for rowDouble := 0; rowDouble < 2; rowDouble++ {
+					p := ((y*2+rowDouble)*560 + x*2*7 + int(hp)) * 4
+
+					if Monochrome {
+						b := float64(halfPixels[hp])
+						pixels[p+0] = byte(0xff * float64(0.20) * b)
+						pixels[p+1] = byte(0xff * float64(0.75) * b)
+						pixels[p+2] = byte(0xff * float64(0.20) * b)
+						pixels[p+3] = 0xff
+					} else {
+						pixels[p+0] = colors[color].R
+						pixels[p+1] = colors[color].G
+						pixels[p+2] = colors[color].B
+						pixels[p+3] = 0xff
+					}
+				}
 			}
 		}
 	}