diff --git a/README.md b/README.md
index 4764205..cf50a86 100644
--- a/README.md
+++ b/README.md
@@ -82,4 +82,14 @@ Assemble the tests
 * 80 column card
 * 48k aux memory
 * double hires
-* joystick
\ No newline at end of file
+* joystick
+
+## Coding standards
+
+Use `gofmt` to ensure standard go style consistency
+
+     go fmt $(go list ./... | grep -v /vendor/)
+
+Use `golint` to ensure Google's style consistency
+
+    golint $(go list ./...)
diff --git a/apple2.go b/apple2.go
index 5f5ce7f..266c899 100644
--- a/apple2.go
+++ b/apple2.go
@@ -65,7 +65,7 @@ func update(screen *ebiten.Image) error {
 	exitAtBreak := true        // Die if a BRK instruction is seen
 
 	// Run for 1/60 of a second, the duration of an ebiten frame
-	cpu.Run(*showInstructions, breakAddress, exitAtBreak, *disableFirmwareWait, system.CpuFrequency/60)
+	cpu.Run(*showInstructions, breakAddress, exitAtBreak, *disableFirmwareWait, system.CPUFrequency/60)
 
 	// Process any audio speaker clicks from this frame
 	audio.ForwardToFrameCycle()
diff --git a/audio/audio.go b/audio/audio.go
index f501be5..7e80f3b 100644
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -18,10 +18,11 @@ func Click() {
 func attenuate(sample int16) int16 {
 	if system.AudioAttenuationCounter == 0 {
 		return 0
-	} else {
-		system.AudioAttenuationCounter--
-		return sample
 	}
+
+	system.AudioAttenuationCounter--
+	return sample
+
 }
 
 // ForwardToFrameCycle calculates how many audio samples need to be written to
@@ -29,7 +30,7 @@ func attenuate(sample int16) int16 {
 // flush and shove them into the channel.
 func ForwardToFrameCycle() {
 	// 1023000/44100=23.19 cycles per audio sample
-	cyclesPerAudioSample := system.CpuFrequency / float64(system.AudioSampleRate)
+	cyclesPerAudioSample := system.CPUFrequency / float64(system.AudioSampleRate)
 
 	// Should be about 1023000/60=17050
 	elapsedCycles := system.FrameCycles - system.LastAudioCycles
diff --git a/audio/ebiten.go b/audio/ebiten.go
index 59452f4..2c449c6 100644
--- a/audio/ebiten.go
+++ b/audio/ebiten.go
@@ -10,11 +10,17 @@ import (
 )
 
 var (
-	audioContext            *ebiten_audio.Context // Ebitem audio context
-	player                  *ebiten_audio.Player  // Ebitem stream player
-	firstAudio              bool                  // True at startup
-	Mute                    bool                  // Mute
-	ClickWhenDriveHeadMoves bool                  // Click speaker when the drive head moves
+	audioContext *ebiten_audio.Context // Ebitem audio context
+	player       *ebiten_audio.Player  // Ebitem stream player
+	firstAudio   bool                  // True at startup
+)
+
+var (
+	// Mute ensures no samples are output
+	Mute bool
+
+	// ClickWhenDriveHeadMoves makes the speaker click once every time the stepper motor magnets change
+	ClickWhenDriveHeadMoves bool
 )
 
 // The streaming code is based on the ebiten sinewave example
diff --git a/bank_switch_test.go b/bank_switch_test.go
index a5ab1f8..23774c2 100644
--- a/bank_switch_test.go
+++ b/bank_switch_test.go
@@ -11,9 +11,9 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func assertMemoryConfiguration(t *testing.T, address uint16, upperRamReadOnly bool, upperReadMappedToROM bool, d000Bank int) {
+func assertMemoryConfiguration(t *testing.T, address uint16, upperRAMReadOnly bool, upperReadMappedToROM bool, d000Bank int) {
 	mmu.WriteMemory(address, 0x00)
-	assert.Equal(t, upperRamReadOnly, mmu.UpperRamReadOnly)
+	assert.Equal(t, upperRAMReadOnly, mmu.UpperRAMReadOnly)
 	assert.Equal(t, upperReadMappedToROM, mmu.UpperReadMappedToROM)
 	assert.Equal(t, d000Bank, mmu.D000Bank)
 }
@@ -67,7 +67,7 @@ func TestBankSwitching(t *testing.T) {
 
 	// Set d000 RAM to bank 1, RAM to read only and attempt writes
 	mmu.SetD000Bank(1)
-	mmu.SetUpperRamReadOnly(true)
+	mmu.SetUpperRAMReadOnly(true)
 	assert.Equal(t, uint8(0xfd), mmu.PhysicalMemory.MainMemory[0xc000]) // bank #1 RAM
 	assert.Equal(t, uint8(0xfe), mmu.PhysicalMemory.MainMemory[0xd000]) // bank #2 RAM
 	mmu.WriteMemory(0xd000, 0x01)                                       // attempt to write to read only RAM
@@ -77,7 +77,7 @@ func TestBankSwitching(t *testing.T) {
 	assert.Equal(t, uint8(0xff), mmu.PhysicalMemory.MainMemory[0xffff]) // top of RAM is unchanged
 
 	// Set RAM to write and write to it
-	mmu.SetUpperRamReadOnly(false)
+	mmu.SetUpperRAMReadOnly(false)
 	mmu.WriteMemory(0xd000, 0xfc)                                       // write to RAM
 	mmu.WriteMemory(0xffff, 0xfb)                                       // write to RAM
 	assert.Equal(t, uint8(0xfc), mmu.PhysicalMemory.MainMemory[0xc000]) // bank #1 RAM has been updated
diff --git a/bell_test.go b/bell_test.go
index 88850bb..38af0a0 100644
--- a/bell_test.go
+++ b/bell_test.go
@@ -24,7 +24,7 @@ func testBellCycles(delay int) {
 	exitAtBreak := false
 	disableFirmwareWait := false
 	cpu.State.PC = 0x800
-	cpu.Run(showInstructions, &breakAddress, exitAtBreak, disableFirmwareWait, system.CpuFrequency*1000)
+	cpu.Run(showInstructions, &breakAddress, exitAtBreak, disableFirmwareWait, system.CPUFrequency*1000)
 
 	// See http://apple2.org.za/gswv/a2zine/GS.WorldView/Resources/USEFUL.TABLES/WAIT.DELAY.CR.txt
 	expectedCycles := (26 + 27*delay + 5*delay*delay) / 2
diff --git a/cpu/cpu.go b/cpu/cpu.go
index 4bb76b0..8d65274 100644
--- a/cpu/cpu.go
+++ b/cpu/cpu.go
@@ -9,16 +9,17 @@ import (
 )
 
 const (
-	CpuFlagC byte = 1 << iota // 0x01 carry
-	CpuFlagZ                  // 0x02 zero
-	CpuFlagI                  // 0x04 interrupt disable
-	CpuFlagD                  // 0x08 decimal mode
-	CpuFlagB                  // 0x10 break
-	CpuFlagR                  // 0x20 reserved (unused)
-	CpuFlagV                  // 0x40 overflow
-	CpuFlagN                  // 0x80 sign/negative
+	cpuFlagC byte = 1 << iota // 0x01 carry
+	cpuFlagZ                  // 0x02 zero
+	cpuFlagI                  // 0x04 interrupt disable
+	cpuFlagD                  // 0x08 decimal mode
+	cpuFlagB                  // 0x10 break
+	cpuFlagR                  // 0x20 reserved (unused)
+	cpuFlagV                  // 0x40 overflow
+	cpuFlagN                  // 0x80 sign/negative
 )
 
+// State contains the CPU state
 var State struct {
 	A  uint8  // accumulator
 	X  uint8  // X register
@@ -40,70 +41,70 @@ func Init() {
 	State.A = 0
 	State.X = 0
 	State.Y = 0
-	State.P = CpuFlagR | CpuFlagB | CpuFlagZ
+	State.P = cpuFlagR | cpuFlagB | cpuFlagZ
 	State.SP = 0xff
 }
 
 // setC sets the carry flag
 func setC(value bool) {
 	if value {
-		State.P |= CpuFlagC
+		State.P |= cpuFlagC
 	} else {
-		State.P &= ^CpuFlagC
+		State.P &= ^cpuFlagC
 	}
 }
 
 // setV sets the overflow flag
 func setV(value bool) {
 	if value {
-		State.P |= CpuFlagV
+		State.P |= cpuFlagV
 	} else {
-		State.P &= ^CpuFlagV
+		State.P &= ^cpuFlagV
 	}
 }
 
 // setN sets the sign/negative flag if the value is negative (>=0x80)
 func setN(value uint8) {
 	if (value & 0x80) != 0 {
-		State.P |= CpuFlagN
+		State.P |= cpuFlagN
 	} else {
-		State.P &= ^CpuFlagN
+		State.P &= ^cpuFlagN
 	}
 }
 
 // setZ sets the zero flag if the value is zero
 func setZ(value uint8) {
 	if value == 0 {
-		State.P |= CpuFlagZ
+		State.P |= cpuFlagZ
 	} else {
-		State.P &= ^CpuFlagZ
+		State.P &= ^cpuFlagZ
 	}
 }
 
 func isC() bool {
-	return (State.P & CpuFlagC) != 0
+	return (State.P & cpuFlagC) != 0
 }
 
 func isZ() bool {
-	return (State.P & CpuFlagZ) != 0
+	return (State.P & cpuFlagZ) != 0
 }
 
 func isD() bool {
-	return (State.P & CpuFlagD) != 0
+	return (State.P & cpuFlagD) != 0
 }
 
 func isV() bool {
-	return (State.P & CpuFlagV) != 0
+	return (State.P & cpuFlagV) != 0
 }
 
 func isN() bool {
-	return (State.P & CpuFlagN) != 0
+	return (State.P & cpuFlagN) != 0
 }
 
 // push8 pushes an 8 bit value to the stack
 func push8(value uint8) {
 	mmu.WritePageTable[mmu.StackPage][State.SP] = value
-	State.SP -= 1
+	State.SP--
 	State.SP &= 0xff
 }
 
@@ -117,7 +118,7 @@ func push16(value uint16) {
 
 // pop8 pulls an 8 bit value from the stack
 func pop8() uint8 {
-	State.SP += 1
+	State.SP++
 	State.SP &= 0xff
 	return mmu.ReadPageTable[mmu.StackPage][State.SP]
 }
@@ -153,7 +154,7 @@ func branch(doBranch bool) {
 		// The number of cycles depends on if a page boundary was crossed
 		samePage := (State.PC & 0xff00) == (relativeAddress & 0xff00)
 		if samePage {
-			system.FrameCycles += 1
+			system.FrameCycles++
 		} else {
 			system.FrameCycles += 2
 		}
@@ -479,7 +480,7 @@ func postProcessShift(addressMode byte, address uint16, value uint8) {
 	switch addressMode {
 	case amAccumulator:
 		State.A = value
-		State.PC += 1
+		State.PC++
 		system.FrameCycles += 2
 	case amZeroPage:
 		mmu.WriteMemory(address, value)
@@ -523,27 +524,27 @@ func postProcessIncDec(addressMode byte) {
 
 func brk() {
 	push16(State.PC + 2)
-	State.P |= CpuFlagB
+	State.P |= cpuFlagB
 	push8(State.P)
-	State.P |= CpuFlagI
+	State.P |= cpuFlagI
 	State.PC = uint16(mmu.ReadMemory(0xffff))<<8 + uint16(mmu.ReadMemory(0xfffe))
 	system.FrameCycles += 7
 }
 
 func irq() {
 	push16(State.PC)
-	State.P &= ^CpuFlagB
+	State.P &= ^cpuFlagB
 	push8(State.P)
-	State.P |= CpuFlagI
+	State.P |= cpuFlagI
 	State.PC = uint16(mmu.ReadMemory(0xffff))<<8 + uint16(mmu.ReadMemory(0xfffe))
 	system.FrameCycles += 7
 }
 
 func nmi() {
 	push16(State.PC)
-	State.P &= ^CpuFlagB
+	State.P &= ^cpuFlagB
 	push8(State.P)
-	State.P |= CpuFlagI
+	State.P |= cpuFlagI
 	State.PC = uint16(mmu.ReadMemory(0xfffb))<<8 + uint16(mmu.ReadMemory(0xfffa))
 	system.FrameCycles += 7
 }
@@ -572,7 +573,7 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 		}
 
 		// Handle an IRQ f there is one pending and interrupts are enabled
-		if system.PendingInterrupt && ((State.P & CpuFlagI) == 0) {
+		if system.PendingInterrupt && ((State.P & cpuFlagI) == 0) {
 			irq()
 			system.PendingInterrupt = false
 			continue
@@ -761,23 +762,23 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 			State.PC++
 			system.FrameCycles += 2
 		case 0x58: // CLI
-			State.P &= ^CpuFlagI
+			State.P &= ^cpuFlagI
 			State.PC++
 			system.FrameCycles += 2
 		case 0x78: // SEI
-			State.P |= CpuFlagI
+			State.P |= cpuFlagI
 			State.PC++
 			system.FrameCycles += 2
 		case 0xb8: // CLV
-			State.P &= ^CpuFlagV
+			State.P &= ^cpuFlagV
 			State.PC++
 			system.FrameCycles += 2
 		case 0xd8: // CLD
-			State.P &= ^CpuFlagD
+			State.P &= ^cpuFlagD
 			State.PC++
 			system.FrameCycles += 2
 		case 0xf8: //SED
-			State.P |= CpuFlagD
+			State.P |= cpuFlagD
 			State.PC++
 			system.FrameCycles += 2
 
@@ -795,12 +796,12 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 		case 0x08: // PHP
 			// From http://visual6502.org/wiki/index.php?title=6502_BRK_and_B_bit#the_B_flag_and_the_various_mechanisms
 			// software instructions BRK & PHP will push the B flag as being 1.
-			push8(State.P | CpuFlagB)
+			push8(State.P | cpuFlagB)
 			State.PC++
 			system.FrameCycles += 3
 		case 0x28: // PLP
-			// CpuFlagR is always supposed to be 1
-			State.P = pop8() | CpuFlagR
+			// cpuFlagR is always supposed to be 1
+			State.P = pop8() | cpuFlagR
 			State.PC++
 			system.FrameCycles += 4
 		case 0xea:
@@ -810,7 +811,7 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 		case 0x00: // BRK
 			brk()
 		case 0x40: // RTI
-			State.P = pop8() | CpuFlagR
+			State.P = pop8() | cpuFlagR
 			value := pop16()
 			State.PC = value
 			system.FrameCycles += 6
@@ -845,7 +846,7 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 			address, value := preProcessShift(addressMode)
 			value16 := uint16(value)
 			value16 <<= 1
-			if (State.P & CpuFlagC) != 0 {
+			if (State.P & cpuFlagC) != 0 {
 				value16 |= 0x01
 			}
 			setC((value16 & 0x100) != 0)
@@ -856,7 +857,7 @@ func Run(showInstructions bool, breakAddress *uint16, exitAtBreak bool, disableF
 		case 0x6a, 0x66, 0x76, 0x6e, 0x7e: // ROR
 			address, value := preProcessShift(addressMode)
 			value16 := uint16(value)
-			if (State.P & CpuFlagC) != 0 {
+			if (State.P & cpuFlagC) != 0 {
 				value16 |= 0x100
 			}
 			setC((value16 & 0x01) != 0)
diff --git a/cpu/debug.go b/cpu/debug.go
index 451a1c8..c179d27 100644
--- a/cpu/debug.go
+++ b/cpu/debug.go
@@ -29,14 +29,14 @@ func printInstruction(instruction string, showRegisters bool) {
 			State.P,
 		)
 
-		printFlag(State.P, CpuFlagN, "n")
-		printFlag(State.P, CpuFlagV, "v")
-		fmt.Print("-") // CpuFlagR flag that's always 1
-		printFlag(State.P, CpuFlagB, "b")
-		printFlag(State.P, CpuFlagD, "d")
-		printFlag(State.P, CpuFlagI, "i")
-		printFlag(State.P, CpuFlagZ, "z")
-		printFlag(State.P, CpuFlagC, "c")
+		printFlag(State.P, cpuFlagN, "n")
+		printFlag(State.P, cpuFlagV, "v")
+		fmt.Print("-") // cpuFlagR flag that's always 1
+		printFlag(State.P, cpuFlagB, "b")
+		printFlag(State.P, cpuFlagD, "d")
+		printFlag(State.P, cpuFlagI, "i")
+		printFlag(State.P, cpuFlagZ, "z")
+		printFlag(State.P, cpuFlagC, "c")
 	}
 
 	fmt.Println("")
diff --git a/cpu/opcodes.go b/cpu/opcodes.go
index 3e84f64..a93945a 100644
--- a/cpu/opcodes.go
+++ b/cpu/opcodes.go
@@ -311,6 +311,7 @@ func initOpCodes() {
 	opCodes[0xFF] = opCode{mnemonic: "???", addressingMode: addressingModes[amExpansion]}
 }
 
+// InitInstructionDecoder initializes tables used for the instruction decoding
 func InitInstructionDecoder() {
 	initAddressingModes()
 	initOpCodes()
diff --git a/disk/disk.go b/disk/disk.go
index f46f9fd..9b0db5b 100644
--- a/disk/disk.go
+++ b/disk/disk.go
@@ -123,7 +123,7 @@ func InitDiskImage() {
 	resetsectorWriteState()
 }
 
-// InitDiskImage reads a disk image from file
+// ReadDiskImage reads a disk image from file
 func ReadDiskImage(path string) {
 	imagePath = path
 
@@ -329,7 +329,7 @@ func decodeAddressField(data []uint8) addressField {
 	return af
 }
 
-// Read a byte from the disk head and spin the disk along
+// ReadTrackData reads a byte from the disk head and spins the disk along
 func ReadTrackData() (result uint8) {
 	result = trackData[system.DriveState.BytePosition]
 
@@ -377,7 +377,7 @@ func WriteTrackData(value uint8) {
 		}
 
 		sectorWriteState.RawData[sectorWriteState.RawDataPosition] = value
-		sectorWriteState.RawDataPosition += 1
+		sectorWriteState.RawDataPosition++
 
 		// Check for address prologue
 		if sectorWriteState.RawDataPosition > 2 && sectorWriteState.RawData[sectorWriteState.RawDataPosition-3] == 0xd5 &&
@@ -393,7 +393,7 @@ func WriteTrackData(value uint8) {
 
 	} else if sectorWriteState.State == receivingData {
 		sectorWriteState.RawData[sectorWriteState.RawDataPosition] = value
-		sectorWriteState.RawDataPosition += 1
+		sectorWriteState.RawDataPosition++
 
 		if sectorWriteState.RawDataPosition == 0x56+0x100 {
 			// We have the full sector data
diff --git a/keyboard/keyboard.go b/keyboard/keyboard.go
index db6bf9a..1b250bf 100644
--- a/keyboard/keyboard.go
+++ b/keyboard/keyboard.go
@@ -4,7 +4,7 @@ import (
 	"github.com/hajimehoshi/ebiten"
 )
 
-var ebitenAsciiMap map[ebiten.Key]uint8 // ebiten keys mapped to ASCII
+var ebitenASCIIMap map[ebiten.Key]uint8 // ebiten keys mapped to ASCII
 var shiftMap map[uint8]uint8            // ebiten keys mapped to ASCII when shift is pressed
 var controlMap map[uint8]uint8          // ebiten keys mapped to ASCII when control is pressed
 
@@ -19,68 +19,68 @@ func Init() {
 	strobe = 0
 	capsLock = true
 
-	ebitenAsciiMap = make(map[ebiten.Key]uint8)
+	ebitenASCIIMap = make(map[ebiten.Key]uint8)
 	shiftMap = make(map[uint8]uint8)
 	controlMap = make(map[uint8]uint8)
 	previousKeysPressed = make(map[uint8]bool)
 
-	ebitenAsciiMap[ebiten.KeyLeft] = 8
-	ebitenAsciiMap[ebiten.KeyTab] = 9
-	ebitenAsciiMap[ebiten.KeyDown] = 10
-	ebitenAsciiMap[ebiten.KeyUp] = 11
-	ebitenAsciiMap[ebiten.KeyEnter] = 13
-	ebitenAsciiMap[ebiten.KeyRight] = 21
-	ebitenAsciiMap[ebiten.KeyEscape] = 27
-	ebitenAsciiMap[ebiten.KeyDelete] = 127
+	ebitenASCIIMap[ebiten.KeyLeft] = 8
+	ebitenASCIIMap[ebiten.KeyTab] = 9
+	ebitenASCIIMap[ebiten.KeyDown] = 10
+	ebitenASCIIMap[ebiten.KeyUp] = 11
+	ebitenASCIIMap[ebiten.KeyEnter] = 13
+	ebitenASCIIMap[ebiten.KeyRight] = 21
+	ebitenASCIIMap[ebiten.KeyEscape] = 27
+	ebitenASCIIMap[ebiten.KeyDelete] = 127
 
-	ebitenAsciiMap[ebiten.Key0] = '0'
-	ebitenAsciiMap[ebiten.Key1] = '1'
-	ebitenAsciiMap[ebiten.Key2] = '2'
-	ebitenAsciiMap[ebiten.Key3] = '3'
-	ebitenAsciiMap[ebiten.Key4] = '4'
-	ebitenAsciiMap[ebiten.Key5] = '5'
-	ebitenAsciiMap[ebiten.Key6] = '6'
-	ebitenAsciiMap[ebiten.Key7] = '7'
-	ebitenAsciiMap[ebiten.Key8] = '8'
-	ebitenAsciiMap[ebiten.Key9] = '9'
-	ebitenAsciiMap[ebiten.KeyA] = 'a'
-	ebitenAsciiMap[ebiten.KeyB] = 'b'
-	ebitenAsciiMap[ebiten.KeyC] = 'c'
-	ebitenAsciiMap[ebiten.KeyD] = 'd'
-	ebitenAsciiMap[ebiten.KeyE] = 'e'
-	ebitenAsciiMap[ebiten.KeyF] = 'f'
-	ebitenAsciiMap[ebiten.KeyG] = 'g'
-	ebitenAsciiMap[ebiten.KeyH] = 'h'
-	ebitenAsciiMap[ebiten.KeyI] = 'i'
-	ebitenAsciiMap[ebiten.KeyJ] = 'j'
-	ebitenAsciiMap[ebiten.KeyK] = 'k'
-	ebitenAsciiMap[ebiten.KeyL] = 'l'
-	ebitenAsciiMap[ebiten.KeyM] = 'm'
-	ebitenAsciiMap[ebiten.KeyN] = 'n'
-	ebitenAsciiMap[ebiten.KeyO] = 'o'
-	ebitenAsciiMap[ebiten.KeyP] = 'p'
-	ebitenAsciiMap[ebiten.KeyQ] = 'q'
-	ebitenAsciiMap[ebiten.KeyR] = 'r'
-	ebitenAsciiMap[ebiten.KeyS] = 's'
-	ebitenAsciiMap[ebiten.KeyT] = 't'
-	ebitenAsciiMap[ebiten.KeyU] = 'u'
-	ebitenAsciiMap[ebiten.KeyV] = 'v'
-	ebitenAsciiMap[ebiten.KeyW] = 'w'
-	ebitenAsciiMap[ebiten.KeyX] = 'x'
-	ebitenAsciiMap[ebiten.KeyY] = 'y'
-	ebitenAsciiMap[ebiten.KeyZ] = 'z'
-	ebitenAsciiMap[ebiten.KeyApostrophe] = '\''
-	ebitenAsciiMap[ebiten.KeyBackslash] = '\\'
-	ebitenAsciiMap[ebiten.KeyComma] = ','
-	ebitenAsciiMap[ebiten.KeyEqual] = '='
-	ebitenAsciiMap[ebiten.KeyGraveAccent] = '`'
-	ebitenAsciiMap[ebiten.KeyLeftBracket] = '['
-	ebitenAsciiMap[ebiten.KeyMinus] = '-'
-	ebitenAsciiMap[ebiten.KeyPeriod] = '.'
-	ebitenAsciiMap[ebiten.KeyRightBracket] = ']'
-	ebitenAsciiMap[ebiten.KeySemicolon] = ';'
-	ebitenAsciiMap[ebiten.KeySlash] = '/'
-	ebitenAsciiMap[ebiten.KeySpace] = ' '
+	ebitenASCIIMap[ebiten.Key0] = '0'
+	ebitenASCIIMap[ebiten.Key1] = '1'
+	ebitenASCIIMap[ebiten.Key2] = '2'
+	ebitenASCIIMap[ebiten.Key3] = '3'
+	ebitenASCIIMap[ebiten.Key4] = '4'
+	ebitenASCIIMap[ebiten.Key5] = '5'
+	ebitenASCIIMap[ebiten.Key6] = '6'
+	ebitenASCIIMap[ebiten.Key7] = '7'
+	ebitenASCIIMap[ebiten.Key8] = '8'
+	ebitenASCIIMap[ebiten.Key9] = '9'
+	ebitenASCIIMap[ebiten.KeyA] = 'a'
+	ebitenASCIIMap[ebiten.KeyB] = 'b'
+	ebitenASCIIMap[ebiten.KeyC] = 'c'
+	ebitenASCIIMap[ebiten.KeyD] = 'd'
+	ebitenASCIIMap[ebiten.KeyE] = 'e'
+	ebitenASCIIMap[ebiten.KeyF] = 'f'
+	ebitenASCIIMap[ebiten.KeyG] = 'g'
+	ebitenASCIIMap[ebiten.KeyH] = 'h'
+	ebitenASCIIMap[ebiten.KeyI] = 'i'
+	ebitenASCIIMap[ebiten.KeyJ] = 'j'
+	ebitenASCIIMap[ebiten.KeyK] = 'k'
+	ebitenASCIIMap[ebiten.KeyL] = 'l'
+	ebitenASCIIMap[ebiten.KeyM] = 'm'
+	ebitenASCIIMap[ebiten.KeyN] = 'n'
+	ebitenASCIIMap[ebiten.KeyO] = 'o'
+	ebitenASCIIMap[ebiten.KeyP] = 'p'
+	ebitenASCIIMap[ebiten.KeyQ] = 'q'
+	ebitenASCIIMap[ebiten.KeyR] = 'r'
+	ebitenASCIIMap[ebiten.KeyS] = 's'
+	ebitenASCIIMap[ebiten.KeyT] = 't'
+	ebitenASCIIMap[ebiten.KeyU] = 'u'
+	ebitenASCIIMap[ebiten.KeyV] = 'v'
+	ebitenASCIIMap[ebiten.KeyW] = 'w'
+	ebitenASCIIMap[ebiten.KeyX] = 'x'
+	ebitenASCIIMap[ebiten.KeyY] = 'y'
+	ebitenASCIIMap[ebiten.KeyZ] = 'z'
+	ebitenASCIIMap[ebiten.KeyApostrophe] = '\''
+	ebitenASCIIMap[ebiten.KeyBackslash] = '\\'
+	ebitenASCIIMap[ebiten.KeyComma] = ','
+	ebitenASCIIMap[ebiten.KeyEqual] = '='
+	ebitenASCIIMap[ebiten.KeyGraveAccent] = '`'
+	ebitenASCIIMap[ebiten.KeyLeftBracket] = '['
+	ebitenASCIIMap[ebiten.KeyMinus] = '-'
+	ebitenASCIIMap[ebiten.KeyPeriod] = '.'
+	ebitenASCIIMap[ebiten.KeyRightBracket] = ']'
+	ebitenASCIIMap[ebiten.KeySemicolon] = ';'
+	ebitenASCIIMap[ebiten.KeySlash] = '/'
+	ebitenASCIIMap[ebiten.KeySpace] = ' '
 
 	shiftMap['1'] = '!'
 	shiftMap['2'] = '@'
@@ -198,7 +198,7 @@ func Poll() {
 	newKeysPressed := make(map[uint8]bool)
 
 	// Query ebiten for all possible keys
-	for k, v := range ebitenAsciiMap {
+	for k, v := range ebitenASCIIMap {
 		if ebiten.IsKeyPressed(k) {
 			allKeysPressed[v] = true
 
diff --git a/mmu/io.go b/mmu/io.go
index 57c1aeb..1fc0bb6 100644
--- a/mmu/io.go
+++ b/mmu/io.go
@@ -14,83 +14,83 @@ import (
 // https://github.com/cmosher01/Apple-II-Platform/blob/master/asminclude/iorom.asm
 
 const (
-	KEYBOARD = 0xC000 // keyboard data (latched) (RD-only)
-	CLR80COL = 0xC000 // use 80-column memory mapping (WR-only)
-	SET80COL = 0xC001
-	CLRAUXRD = 0xC002 // read from auxilliary 48K
-	SETAUXRD = 0xC003
-	CLRAUXWR = 0xC004 // write to auxilliary 48K
-	SETAUXWR = 0xC005
-	CLRCXROM = 0xC006 // use external slot ROM
-	SETCXROM = 0xC007
-	CLRAUXZP = 0xC008 // use auxilliary ZP, stack, & LC
-	SETAUXZP = 0xC009
-	CLRC3ROM = 0xC00A // use external slot C3 ROM
-	SETC3ROM = 0xC00B
-	CLR80VID = 0xC00C // use 80-column display mode
-	SET80VID = 0xC00D
-	CLRALTCH = 0xC00E // use alternate character set ROM
-	SETALTCH = 0xC00F
-	STROBE   = 0xC010 // strobe (unlatch) keyboard data
+	mKEYBOARD = 0xC000 // keyboard data (latched) (RD-only)
+	mCLR80COL = 0xC000 // use 80-column memory mapping (WR-only)
+	mSET80COL = 0xC001
+	mCLRAUXRD = 0xC002 // read from auxilliary 48K
+	mSETAUXRD = 0xC003
+	mCLRAUXWR = 0xC004 // write to auxilliary 48K
+	mSETAUXWR = 0xC005
+	mCLRCXROM = 0xC006 // use external slot ROM
+	mSETCXROM = 0xC007
+	mCLRAUXZP = 0xC008 // use auxilliary ZP, stack, & LC
+	mSETAUXZP = 0xC009
+	mCLRC3ROM = 0xC00A // use external slot C3 ROM
+	mSETC3ROM = 0xC00B
+	mCLR80VID = 0xC00C // use 80-column display mode
+	mSET80VID = 0xC00D
+	mCLRALTCH = 0xC00E // use alternate character set ROM
+	mSETALTCH = 0xC00F
+	mSTROBE   = 0xC010 // strobe (unlatch) keyboard data
 
-	RDLCBNK2 = 0xC011 // reading from LC bank $Dx 2
-	RDLCRAM  = 0xC012 // reading from LC RAM
-	RDRAMRD  = 0xC013 // reading from auxilliary 48K
-	RDRAMWR  = 0xC014 // writing to auxilliary 48K
-	RDCXROM  = 0xC015 // using external slot ROM
-	RDAUXZP  = 0xC016 // using auxilliary ZP, stack, & LC
-	RDC3ROM  = 0xC017 // using external slot C3 ROM
-	RD80COL  = 0xC018 // using 80-column memory mapping
-	RDVBLBAR = 0xC019 // not VBL (VBL signal low)
-	RDTEXT   = 0xC01A // using text mode
-	RDMIXED  = 0xC01B // using mixed mode
-	RDPAGE2  = 0xC01C // using text/graphics page2
-	RDHIRES  = 0xC01D // using Hi-res graphics mode
-	RDALTCH  = 0xC01E // using alternate character set ROM
-	RD80VID  = 0xC01F // using 80-column display mode
-	SPEAKER  = 0xC030 // toggle speaker diaphragm
+	mRDLCBNK2 = 0xC011 // reading from LC bank $Dx 2
+	mRDLCRAM  = 0xC012 // reading from LC RAM
+	mRDRAMRD  = 0xC013 // reading from auxilliary 48K
+	mRDRAMWR  = 0xC014 // writing to auxilliary 48K
+	mRDCXROM  = 0xC015 // using external slot ROM
+	mRDAUXZP  = 0xC016 // using auxilliary ZP, stack, & LC
+	mRDC3ROM  = 0xC017 // using external slot C3 ROM
+	mRD80COL  = 0xC018 // using 80-column memory mapping
+	mRDVBLBAR = 0xC019 // not VBL (VBL signal low)
+	mRDTEXT   = 0xC01A // using text mode
+	mRDMIXED  = 0xC01B // using mixed mode
+	mRDPAGE2  = 0xC01C // using text/graphics page2
+	mRDHIRES  = 0xC01D // using Hi-res graphics mode
+	mRDALTCH  = 0xC01E // using alternate character set ROM
+	mRD80VID  = 0xC01F // using 80-column display mode
+	mSPEAKER  = 0xC030 // toggle speaker diaphragm
 
-	CLRTEXT  = 0xC050 // enable text-only mode
-	SETTEXT  = 0xC051
-	CLRMIXED = 0xC052 // enable graphics/text mixed mode
-	SETMIXED = 0xC053
-	TXTPAGE1 = 0xC054 // select page1/2 (or page1/1x)
-	TXTPAGE2 = 0xC055
-	CLRHIRES = 0xC056 // enable Hi-res graphics
-	SETHIRES = 0xC057
+	mCLRTEXT  = 0xC050 // enable text-only mode
+	mSETTEXT  = 0xC051
+	mCLRMIXED = 0xC052 // enable graphics/text mixed mode
+	mSETMIXED = 0xC053
+	mTXTPAGE1 = 0xC054 // select page1/2 (or page1/1x)
+	mTXTPAGE2 = 0xC055
+	mCLRHIRES = 0xC056 // enable Hi-res graphics
+	mSETHIRES = 0xC057
 
-	SETAN0 = 0xC058 // 4-bit annunciator inputs
-	CLRAN0 = 0xC059
-	SETAN1 = 0xC05A
-	CLRAN1 = 0xC05B
-	SETAN2 = 0xC05C
-	CLRAN2 = 0xC05D
-	SETAN3 = 0xC05E
-	CLRAN3 = 0xC05F
+	mSETAN0 = 0xC058 // 4-bit annunciator inputs
+	mCLRAN0 = 0xC059
+	mSETAN1 = 0xC05A
+	mCLRAN1 = 0xC05B
+	mSETAN2 = 0xC05C
+	mCLRAN2 = 0xC05D
+	mSETAN3 = 0xC05E
+	mCLRAN3 = 0xC05F
 
-	OPNAPPLE = 0xC061 // open apple (command) key data
-	CLSAPPLE = 0xC062 // closed apple (option) key data
-	STATEREG = 0xC068 // Has no effect on //e
+	mOPNAPPLE = 0xC061 // open apple (command) key data
+	mCLSAPPLE = 0xC062 // closed apple (option) key data
+	mSTATEREG = 0xC068 // Has no effect on //e
 
-	PDLTRIG = 0xC070 // trigger paddles
+	mPDLTRIG = 0xC070 // trigger paddles
 
 	// Slot 6 Drive IO
-	S6CLRDRVP0 = 0xC0E0 // stepper phase 0  (Q0)
-	S6SETDRVP0 = 0xC0E1 //
-	S6CLRDRVP1 = 0xC0E2 // stepper phase 1  (Q1)
-	S6SETDRVP1 = 0xC0E3 //
-	S6CLRDRVP2 = 0xC0E4 // stepper phase 2  (Q2)
-	S6SETDRVP2 = 0xC0E5 //
-	S6CLRDRVP3 = 0xC0E6 // stepper phase 3  (Q3)
-	S6SETDRVP3 = 0xC0E7 //
-	S6MOTOROFF = 0xC0E8 // drive motor      (Q4)
-	S6MOTORON  = 0xC0E9 //
-	S6SELDRV1  = 0xC0EA // drive select     (Q5)
-	S6SELDRV2  = 0xC0EB //
-	S6Q6L      = 0xC0EC // read             (Q6)
-	S6Q6H      = 0xC0ED // WP sense
-	S6Q7L      = 0xC0EE // WP sense/read    (Q7)
-	S6Q7H      = 0xC0EF // write
+	mS6CLRDRVP0 = 0xC0E0 // stepper phase 0  (Q0)
+	mS6SETDRVP0 = 0xC0E1 //
+	mS6CLRDRVP1 = 0xC0E2 // stepper phase 1  (Q1)
+	mS6SETDRVP1 = 0xC0E3 //
+	mS6CLRDRVP2 = 0xC0E4 // stepper phase 2  (Q2)
+	mS6SETDRVP2 = 0xC0E5 //
+	mS6CLRDRVP3 = 0xC0E6 // stepper phase 3  (Q3)
+	mS6SETDRVP3 = 0xC0E7 //
+	mS6MOTOROFF = 0xC0E8 // drive motor      (Q4)
+	mS6MOTORON  = 0xC0E9 //
+	mS6SELDRV1  = 0xC0EA // drive select     (Q5)
+	mS6SELDRV2  = 0xC0EB //
+	mS6Q6L      = 0xC0EC // read             (Q6)
+	mS6Q6H      = 0xC0ED // WP sense
+	mS6Q7L      = 0xC0EE // WP sense/read    (Q7)
+	mS6Q7H      = 0xC0EF // write
 )
 
 // VideoState has 3 booleans which determine the video configuration:
@@ -106,6 +106,7 @@ var VideoState struct {
 	Mixed     bool
 }
 
+// InitIO resets all IO states
 func InitIO() {
 	// Empty slots that aren't yet implemented
 	emptySlot(3)
@@ -138,81 +139,81 @@ func readWrite(address uint16, isRead bool) bool {
 	}
 
 	switch address {
-	case CLRAUXRD:
+	case mCLRAUXRD:
 		SetFakeAuxMemoryRead(false)
 		return true
-	case SETAUXRD:
+	case mSETAUXRD:
 		SetFakeAuxMemoryRead(true)
 		return true
 
-	case CLRAUXWR:
+	case mCLRAUXWR:
 		SetFakeAuxMemoryWrite(false)
 		return true
-	case SETAUXWR:
+	case mSETAUXWR:
 		SetFakeAuxMemoryWrite(true)
 		return true
 
-	case CLRAUXZP:
+	case mCLRAUXZP:
 		SetFakeAltZP(false)
 		return true
-	case SETAUXZP:
+	case mSETAUXZP:
 		SetFakeAltZP(true)
 		return true
 
-	case CLR80VID:
+	case mCLR80VID:
 		SetCol80(false)
 		return true
-	case SET80VID:
+	case mSET80VID:
 		SetCol80(true)
 		return true
 
-	case TXTPAGE1:
+	case mTXTPAGE1:
 		SetPage2(false)
 		return true
-	case TXTPAGE2:
+	case mTXTPAGE2:
 		SetPage2(true)
 		return true
 
-	case CLRTEXT:
+	case mCLRTEXT:
 		VideoState.TextMode = false
 		return true
-	case SETTEXT:
+	case mSETTEXT:
 		VideoState.TextMode = true
 		return true
 
-	case CLRMIXED:
+	case mCLRMIXED:
 		VideoState.Mixed = false
 		return true
-	case SETMIXED:
+	case mSETMIXED:
 		VideoState.Mixed = true
 		return true
 
-	case CLRHIRES:
+	case mCLRHIRES:
 		VideoState.HiresMode = false
 		return true
-	case SETHIRES:
+	case mSETHIRES:
 		VideoState.HiresMode = true
 		return true
 
-	case CLR80COL:
+	case mCLR80COL:
 		if !isRead {
 			SetStore80(false)
 			return true
-		} else {
-			return false
 		}
-	case SET80COL:
+		return false
+
+	case mSET80COL:
 		SetStore80(true)
 		return true
 
-	case STATEREG:
+	case mSTATEREG:
 		// Ignore not implemented memory management reg
 		return true
 
 	// Drive stepper motor phase change
-	case S6CLRDRVP0, S6SETDRVP0, S6CLRDRVP1, S6SETDRVP1, S6CLRDRVP2, S6SETDRVP2, S6CLRDRVP3, S6SETDRVP3:
-		magnet := (address - S6CLRDRVP0) / 2
-		on := ((address - S6CLRDRVP0) % 2) == 1
+	case mS6CLRDRVP0, mS6SETDRVP0, mS6CLRDRVP1, mS6SETDRVP1, mS6CLRDRVP2, mS6SETDRVP2, mS6CLRDRVP3, mS6SETDRVP3:
+		magnet := (address - mS6CLRDRVP0) / 2
+		on := ((address - mS6CLRDRVP0) % 2) == 1
 		if !on {
 			// Turn off the magnet in Phases
 			system.DriveState.Phases &= ^(1 << magnet)
@@ -225,10 +226,10 @@ func readWrite(address uint16, isRead bool) bool {
 		// Move head if a neighboring magnet is on and all others are off
 		direction := int8(0)
 		if (system.DriveState.Phases & (1 << uint8((system.DriveState.Phase+1)&3))) != 0 {
-			direction += 1
+			direction++
 		}
 		if (system.DriveState.Phases & (1 << uint8((system.DriveState.Phase+3)&3))) != 0 {
-			direction -= 1
+			direction--
 		}
 
 		// Move the head
@@ -251,37 +252,37 @@ func readWrite(address uint16, isRead bool) bool {
 
 		return true
 
-	case S6MOTOROFF:
+	case mS6MOTOROFF:
 		system.DriveState.Spinning = false
 		return true
-	case S6MOTORON:
+	case mS6MOTORON:
 		system.DriveState.Spinning = true
 		return true
 
-	case S6SELDRV1:
+	case mS6SELDRV1:
 		system.DriveState.Drive = 1
 		return true
-	case S6SELDRV2:
+	case mS6SELDRV2:
 		system.DriveState.Drive = 2
 		return true
 
-	case S6Q6L:
+	case mS6Q6L:
 		if !isRead {
 			system.DriveState.Q6 = false
 			return true
 		}
 		return false
-	case S6Q6H:
+	case mS6Q6H:
 		if isRead {
 			system.DriveState.Q6 = true
 			return true
 		}
 		return false
 
-	case S6Q7L:
+	case mS6Q7L:
 		system.DriveState.Q7 = false
 		return true
-	case S6Q7H:
+	case mS6Q7H:
 		system.DriveState.Q7 = true
 		return true
 
@@ -299,64 +300,60 @@ func ReadIO(address uint16) uint8 {
 
 	switch address {
 
-	case KEYBOARD, STROBE:
+	case mKEYBOARD, mSTROBE:
 		keyBoardData, strobe := keyboard.Read()
-		if address == KEYBOARD {
+		if address == mKEYBOARD {
 			return keyBoardData
-		} else {
-			keyboard.ResetStrobe()
-			return strobe
 		}
+		keyboard.ResetStrobe()
+		return strobe
 
-	case RDRAMRD, RDRAMWR, RDAUXZP:
+	case mRDRAMRD, mRDRAMWR, mRDAUXZP:
 		panic("Read/write aux memory not implemented")
 		return 0x0d
 
-	case RDCXROM:
+	case mRDCXROM:
 		if UsingExternalSlotRom {
 			return 0x8d
-		} else {
-			return 0x0d
 		}
+		return 0x0d
 
-	case RD80VID:
+	case mRD80VID:
 		// using 80-column display mode not implemented
 		return 0x0d
 
-	case RDPAGE2:
+	case mRDPAGE2:
 		if Page2 {
 			return 0x8d
-		} else {
-			return 0x0d
 		}
+		return 0x0d
 
 	// 4-bit annunciator inputs
-	case SETAN0, CLRAN0, SETAN1, CLRAN1, SETAN2, CLRAN2, SETAN3, CLRAN3:
+	case mSETAN0, mCLRAN0, mSETAN1, mCLRAN1, mSETAN2, mCLRAN2, mSETAN3, mCLRAN3:
 		// Annunciators not implemented
 
-	case OPNAPPLE:
+	case mOPNAPPLE:
 		// Open apple key not implemented
 		return 0
 
-	case CLSAPPLE:
+	case mCLSAPPLE:
 		// Closed apple key not implemented
 
-	case RD80COL:
+	case mRD80COL:
 		if Store80 {
 			return 0x8d
-		} else {
-			return 0x0d
 		}
+		return 0x0d
 
-	case RDALTCH:
+	case mRDALTCH:
 		// RDALTCH not implemented, but it's also used, so don't fail on it.
 		return 0x0d
 
-	case SPEAKER:
+	case mSPEAKER:
 		audio.Click()
 		return 0
 
-	case S6Q6L:
+	case mS6Q6L:
 		// A read from disk
 		return disk.ReadTrackData()
 
@@ -367,7 +364,7 @@ func ReadIO(address uint16) uint8 {
 	return 0
 }
 
-// ReadIO does a write in the $c000-$c0ff area
+// WriteIO does a write in the $c000-$c0ff area
 func WriteIO(address uint16, value uint8) {
 	// Try the generic readWrite and return if it has handled the write
 	if readWrite(address, false) {
@@ -376,29 +373,29 @@ func WriteIO(address uint16, value uint8) {
 
 	switch address {
 
-	case STROBE:
+	case mSTROBE:
 		keyboard.ResetStrobe()
 
-	case CLRCXROM:
+	case mCLRCXROM:
 		MapFirstHalfOfIO()
-	case SETCXROM:
+	case mSETCXROM:
 		MapSecondHalfOfIO()
 
-	case CLRALTCH:
+	case mCLRALTCH:
 		return
-	case SETALTCH:
+	case mSETALTCH:
 		panic("SETALTCH not implemented")
 
-	case CLR80COL:
+	case mCLR80COL:
 		// CLR80COL not implemented
 		return
 
-	case CLRC3ROM:
+	case mCLRC3ROM:
 		// CLRC3ROM not implemented
-	case SETC3ROM:
+	case mSETC3ROM:
 		// SETC3ROM not implemented
 
-	case S6Q6H:
+	case mS6Q6H:
 		// A write to disk
 		disk.WriteTrackData(value)
 
diff --git a/mmu/mmu.go b/mmu/mmu.go
index 3a95d9c..a902c1b 100644
--- a/mmu/mmu.go
+++ b/mmu/mmu.go
@@ -7,8 +7,11 @@ import (
 	"github.com/freewilll/apple2/system"
 )
 
-const RomPath = "apple2e.rom" // So far only one ROM is supported and it's loaded at startup
-const StackPage = 1           // The 6502 stack is at 0x100
+// RomPath is a hardcoded path to an Apple //e ROM file that's loaded at startup
+const RomPath = "apple2e.rom"
+
+// StackPage is the location of the 6504 stack
+const StackPage = 1
 
 // PhysicalMemory contains all the unmapped memory, ROM and RAM
 var PhysicalMemory struct {
@@ -18,8 +21,10 @@ var PhysicalMemory struct {
 	RomC2      [0x1000]uint8  // Second half of IO ROM
 }
 
-// Page tables for read & write
+// ReadPageTable is the page table for reads
 var ReadPageTable [0x100][]uint8
+
+// WritePageTable is the page table for writes
 var WritePageTable [0x100][]uint8
 
 // Memory mapping states
@@ -27,7 +32,7 @@ var (
 	D000Bank             int  // one maps to $c000, two maps to $d000
 	UsingExternalSlotRom bool // Which IO ROM is being used
 	UpperReadMappedToROM bool // Do reads go to the RAM or ROM
-	UpperRamReadOnly     bool // Is the upper RAM read only
+	UpperRAMReadOnly     bool // Is the upper RAM read only
 	FakeAuxMemoryRead    bool // Aux memory isn't implemented
 	FakeAuxMemoryWrite   bool // Aux memory isn't implemented
 	FakeAltZP            bool // Aux memory isn't implemented
@@ -37,7 +42,7 @@ var (
 	Page2                bool // Main memory Page2 is selected
 )
 
-// Make page tables for current RAM, ROM and IO configuration
+// ApplyMemoryConfiguration creates the page tables for current RAM, ROM and IO configuration
 func ApplyMemoryConfiguration() {
 	// Map main RAM for read/write
 	for i := 0x0; i < 0xc0; i++ {
@@ -65,7 +70,7 @@ func ApplyMemoryConfiguration() {
 			ReadPageTable[i] = PhysicalMemory.MainMemory[base : base+0x100]
 		}
 
-		if UpperRamReadOnly {
+		if UpperRAMReadOnly {
 			WritePageTable[i] = nil
 		} else {
 			WritePageTable[i] = PhysicalMemory.MainMemory[base : base+0x100]
@@ -78,7 +83,7 @@ func ApplyMemoryConfiguration() {
 		if !UpperReadMappedToROM {
 			ReadPageTable[i] = PhysicalMemory.MainMemory[base : base+0x100]
 		}
-		if UpperRamReadOnly {
+		if UpperRAMReadOnly {
 			WritePageTable[i] = nil
 		} else {
 			WritePageTable[i] = PhysicalMemory.MainMemory[base : base+0x100]
@@ -93,13 +98,13 @@ func ApplyMemoryConfiguration() {
 
 }
 
-// Map 0xc100-0xcfff for reading from RomC1
+// MapFirstHalfOfIO maps 0xc100-0xcfff for reading from RomC1
 func MapFirstHalfOfIO() {
 	UsingExternalSlotRom = false
 	ApplyMemoryConfiguration()
 }
 
-// Map 0xc100-0xcfff for reading from RomC2
+// MapSecondHalfOfIO map 0xc100-0xcfff for reading from RomC2
 func MapSecondHalfOfIO() {
 	UsingExternalSlotRom = true
 	ApplyMemoryConfiguration()
@@ -131,61 +136,66 @@ func loadApple2eROM() {
 	}
 }
 
+// InitApple2eROM loads the ROM and inits the ROM page tables
 func InitApple2eROM() {
 	loadApple2eROM()
 	MapFirstHalfOfIO() // Map 0xc100-0xcfff for reading
 	InitROM()          // Map 0xd000-0xffff for reading
 }
 
-// Set upper memory area for reading from ROM
+// InitROM sets the upper memory area for reading from ROM
 func InitROM() {
 	UpperReadMappedToROM = true
 	ApplyMemoryConfiguration()
 }
 
+// SetUpperReadMappedToROM sets the upper area so that reads are done from the ROM if true or RAM if false
 func SetUpperReadMappedToROM(value bool) {
 	UpperReadMappedToROM = value
 	ApplyMemoryConfiguration()
 }
 
-func SetUpperRamReadOnly(value bool) {
-	UpperRamReadOnly = value
+// SetUpperRAMReadOnly sets the upper RAM area to read only
+func SetUpperRAMReadOnly(value bool) {
+	UpperRAMReadOnly = value
 	ApplyMemoryConfiguration()
 }
 
-// Set d000 bank to map to $c000 or $d000 in the physical  memory
+// SetD000Bank sets the $d000 bank to map to $c000 or $d000 in the physical  memory
 func SetD000Bank(value int) {
 	D000Bank = value
 	ApplyMemoryConfiguration()
 }
 
-// Aux memory hasn't been implemented. If aux memory is selected, and a read
+// SetFakeAuxMemoryRead sets an internal state to fake aux memory reads. Aux memory hasn't been implemented. If aux memory is selected, and a read
 // is attempted, then nonsense must be returned.
 func SetFakeAuxMemoryRead(value bool) {
 	FakeAuxMemoryRead = value
 	ApplyMemoryConfiguration()
 }
 
-// Aux memory hasn't been implemented. If aux memory is selected, and a write
+// SetFakeAuxMemoryWrite sets an internal state to fake aux memory writes. Aux memory hasn't been implemented. If aux memory is selected, and a write
 // is attempted, then it must be ignored.
 func SetFakeAuxMemoryWrite(value bool) {
 	FakeAuxMemoryWrite = value
 	ApplyMemoryConfiguration()
 }
 
-// Alternate zero page isn't implemented
+// SetFakeAltZP sets an internal state to fake a missing alternate zero page. Alternate zero page isn't implemented
 func SetFakeAltZP(value bool) {
 	FakeAltZP = value
 	ApplyMemoryConfiguration()
 }
 
-// 80 column card isn't implemented
+// SetCol80 sets an internal state to fake a missing 80 column card
 func SetCol80(value bool) {
 	Col80 = value
 	// No changes are needed when this is toggled
 }
 
-// Page switching is only implemented for the main memory
+// SetPage2 sets page1/page2 in text, lores or hires. This only works if the
+// 80 column card is disabled since the 80 columns card has not yet nbeen
+// implemented.
 func SetPage2(value bool) {
 	// If the 80 column card is enabled, then this toggles aux memory
 	// Otherwise, page1/page2 is toggled in the main memory
@@ -197,7 +207,7 @@ func SetPage2(value bool) {
 	}
 }
 
-// 80 column card isn't implemented
+// SetStore80 sets an internal state to fake a missing 80 column card
 func SetStore80(value bool) {
 	Store80 = value
 	FakePage2 = value
@@ -206,7 +216,7 @@ func SetStore80(value bool) {
 
 // InitRAM sets all default RAM memory settings and resets the page tables
 func InitRAM() {
-	UpperRamReadOnly = false
+	UpperRAMReadOnly = false
 	D000Bank = 2
 	FakeAuxMemoryRead = false  // Aux memory isn't implemented
 	FakeAuxMemoryWrite = false // Aux memory isn't implemented
@@ -217,22 +227,23 @@ func InitRAM() {
 	ApplyMemoryConfiguration()
 }
 
+// WipeRAM wipes all the physical RAM
 func WipeRAM() {
 	for i := 0; i < 0x10000; i++ {
 		PhysicalMemory.MainMemory[i] = 0
 	}
 }
 
-// SetMemoryMode is used to set UpperRamReadOnly, UpperReadMappedToROM and D000Bank number
+// SetMemoryMode is used to set UpperRAMReadOnly, UpperReadMappedToROM and D000Bank number
 func SetMemoryMode(mode uint8) {
 	// mode corresponds to a read/write to $c080 with
 	// $c080 mode=$00
 	// $c08f mode=$0f
 
 	if (mode & 1) == 0 {
-		UpperRamReadOnly = true
+		UpperRAMReadOnly = true
 	} else {
-		UpperRamReadOnly = false
+		UpperRAMReadOnly = false
 	}
 
 	if (((mode & 2) >> 1) ^ (mode & 1)) == 0 {
@@ -266,18 +277,18 @@ func ReadMemory(address uint16) uint8 {
 		if address >= 0x200 {
 			// Return nothingness
 			return uint8(0x00)
-		} else {
-			if FakeAltZP {
-				return uint8(0x00)
-			}
 		}
+		if FakeAltZP {
+			return uint8(0x00)
+		}
+
 	}
 
 	// Implicit else, we're reading the main non-IO RAM
 	return ReadPageTable[address>>8][address&0xff]
 }
 
-// ReadMemory writes to the ROM or RAM page table
+// WriteMemory writes to the ROM or RAM page table
 func WriteMemory(address uint16, value uint8) {
 	if (address >= 0xc000) && (address < 0xc100) {
 		WriteIO(address, value)
diff --git a/system/system.go b/system/system.go
index d6d2119..f4469ad 100644
--- a/system/system.go
+++ b/system/system.go
@@ -4,22 +4,46 @@ package system
 // the packages.
 
 const (
-	CpuFrequency    = 1023000 // 6402 CPU frequency in Hz
-	AudioSampleRate = 44100   // Audio sample rate in Hz
+	// CPUFrequency is the 6502 CPU frequency in Hz
+	CPUFrequency = 1023000
+
+	// AudioSampleRate is the audio sample rate in Hz
+	AudioSampleRate = 44100
 )
 
 var (
-	PendingInterrupt        bool       // Set when an interrupt has just happened
-	PendingNMI              bool       // Set when a non maskable interrupt has just happened
-	RunningTests            bool       // For testing
-	RunningFunctionalTests  bool       // For testing
-	RunningInterruptTests   bool       // For testing
-	Cycles                  uint64     // Total CPU cycles executed
-	FrameCycles             uint64     // CPU cycles executed in the current frame
-	AudioChannel            chan int16 // Audio channel
-	LastAudioValue          int16      // + or - value of the current square wave
-	LastAudioCycles         uint64     // Last CPU cycle when audio was sent to the channel
-	AudioAttenuationCounter uint64     // Counter to keep track of when the audio should be zeroed after inactivity
+	// PendingInterrupt is set when an interrupt has just happened
+	PendingInterrupt bool
+
+	// PendingNMI is set when a non maskable interrupt has just happened
+	PendingNMI bool
+
+	// RunningTests is set when  tests are running
+	RunningTests bool
+
+	// RunningFunctionalTests is set when functional tests are running
+	RunningFunctionalTests bool
+
+	// RunningInterruptTests is set when interupt tests are running
+	RunningInterruptTests bool
+
+	// Cycles is the total CPU cycles executed
+	Cycles uint64
+
+	// FrameCycles is the CPU cycles executed in the current frame
+	FrameCycles uint64
+
+	// AudioChannel is the audio channel used to produce and consume audio samples between the cpu and audio packages
+	AudioChannel chan int16
+
+	// LastAudioValue is the + or - value of the current square wave
+	LastAudioValue int16
+
+	// LastAudioCycles is the ast CPU cycle when audio was sent to the channel
+	LastAudioCycles uint64
+
+	// AudioAttenuationCounter is a counter to keep track of when the audio should be zeroed after inactivity
+	AudioAttenuationCounter uint64
 )
 
 // DriveState has the state of the disk drive
@@ -40,7 +64,7 @@ func Init() {
 	LastAudioValue = 0x2000
 }
 
-// Handle a write to a magic test address that triggers an interrupt and/or an NMI
+// WriteInterruptTestOpenCollector handles a write to a magic test address that triggers an interrupt and/or an NMI
 func WriteInterruptTestOpenCollector(address uint16, oldValue uint8, value uint8) {
 	oldInterrupt := (oldValue & 0x1) == 0x1
 	oldNMI := (oldValue & 0x2) == 0x2
diff --git a/utils/utils.go b/utils/utils.go
index 184c2a6..614d602 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -60,7 +60,7 @@ func RunUntilBreakPoint(t *testing.T, breakAddress uint16, seconds int, showInst
 	system.LastAudioCycles = 0
 	exitAtBreak := false
 	disableFirmwareWait := false
-	cpu.Run(showInstructions, &breakAddress, exitAtBreak, disableFirmwareWait, uint64(system.CpuFrequency*seconds))
+	cpu.Run(showInstructions, &breakAddress, exitAtBreak, disableFirmwareWait, uint64(system.CPUFrequency*seconds))
 	if cpu.State.PC != breakAddress {
 		t.Fatalf("Did not reach breakpoint at %04x. Got to %04x", breakAddress, cpu.State.PC)
 	}
diff --git a/video/video.go b/video/video.go
index aa2fe65..1e6fd75 100644
--- a/video/video.go
+++ b/video/video.go
@@ -12,9 +12,11 @@ import (
 )
 
 const (
-	ScreenSizeFactor = 1     // Factor by which the whole screen is resized
-	textVideoMemory  = 0x400 // Base location of page 1 text video memory
-	flashFrames      = 11    // Number of frames when FLASH mode is toggled
+	// 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
 )
 
 // drawTextLoresByte is a function definition used for mixed text/lores rendering
@@ -25,7 +27,9 @@ 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
-	ShowFPS      bool              // Show FPS in corner?
+
+	// ShowFPS determines if the FPS is shown in the corner of the video
+	ShowFPS bool
 )
 
 // initTextCharMap initializes the text character map
@@ -130,7 +134,7 @@ func drawText(screen *ebiten.Image, x int, y int, value uint8) error {
 // drawLores draws two colored lores squares at the equivalent text location x,y.
 func drawLores(screen *ebiten.Image, x int, y int, value uint8) error {
 	// Convert the 8 bit value to two 4 bit values
-	var values [2]uint8 = [2]uint8{value & 0xf, value >> 4}
+	var values = [2]uint8{value & 0xf, value >> 4}
 
 	// Render top & bottom squares
 	for i := 0; i < 2; i++ {