diff --git a/devices/bme280/bme280_test.go b/devices/bme280/bme280_test.go
index 29c4618..69414ec 100644
--- a/devices/bme280/bme280_test.go
+++ b/devices/bme280/bme280_test.go
@@ -46,24 +46,24 @@ func TestSPISense_success(t *testing.T) {
 			Ops: []conntest.IO{
 				// Chipd ID detection.
 				{
-					Write: []byte{0xD0, 0x00},
-					Read:  []byte{0x00, 0x60},
+					W: []byte{0xD0, 0x00},
+					R: []byte{0x00, 0x60},
 				},
 				// Calibration data.
 				{
-					Write: []byte{0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-					Read:  []byte{0x00, 0xC9, 0x6C, 0x63, 0x65, 0x32, 0x00, 0x77, 0x93, 0x98, 0xD5, 0xD0, 0x0B, 0x67, 0x23, 0xBA, 0x00, 0xF9, 0xFF, 0xAC, 0x26, 0x0A, 0xD8, 0xBD, 0x10, 0x00, 0x4B},
+					W: []byte{0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+					R: []byte{0x00, 0xC9, 0x6C, 0x63, 0x65, 0x32, 0x00, 0x77, 0x93, 0x98, 0xD5, 0xD0, 0x0B, 0x67, 0x23, 0xBA, 0x00, 0xF9, 0xFF, 0xAC, 0x26, 0x0A, 0xD8, 0xBD, 0x10, 0x00, 0x4B},
 				},
 				// Calibration data.
 				{
-					Write: []byte{0xE1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-					Read:  []byte{0x00, 0x5C, 0x01, 0x00, 0x15, 0x0F, 0x00, 0x1E},
+					W: []byte{0xE1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+					R: []byte{0x00, 0x5C, 0x01, 0x00, 0x15, 0x0F, 0x00, 0x1E},
 				},
-				{Write: []byte{0x74, 0xB4, 0x72, 0x05, 0x75, 0xA0, 0x74, 0xB7}},
-				// Read.
+				{W: []byte{0x74, 0xB4, 0x72, 0x05, 0x75, 0xA0, 0x74, 0xB7}},
+				// R.
 				{
-					Write: []byte{0xF7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-					Read:  []byte{0x00, 0x51, 0x9F, 0xC0, 0x9E, 0x3A, 0x50, 0x5E, 0x5B},
+					W: []byte{0xF7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+					R: []byte{0x00, 0x51, 0x9F, 0xC0, 0x9E, 0x3A, 0x50, 0x5E, 0x5B},
 				},
 			},
 		},
@@ -112,8 +112,8 @@ func TestNewSPI_fail_len(t *testing.T) {
 			Ops: []conntest.IO{
 				{
 					// Chipd ID detection.
-					Write: []byte{0xD0, 0x00},
-					Read:  []byte{0x00},
+					W: []byte{0xD0, 0x00},
+					R: []byte{0x00},
 				},
 			},
 			DontPanic: true,
@@ -135,8 +135,8 @@ func TestNewSPI_fail_chipid(t *testing.T) {
 			Ops: []conntest.IO{
 				{
 					// Chipd ID detection.
-					Write: []byte{0xD0, 0x00},
-					Read:  []byte{0x00, 0xFF},
+					W: []byte{0xD0, 0x00},
+					R: []byte{0x00, 0xFF},
 				},
 			},
 		},
@@ -153,7 +153,7 @@ func TestNewI2C_fail(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}},
+			{Addr: 0x76, W: []byte{0xd0}},
 		},
 		DontPanic: true,
 	}
@@ -171,7 +171,7 @@ func TestNewI2C_chipid(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}, Read: []byte{0x60}},
+			{Addr: 0x76, W: []byte{0xd0}, R: []byte{0x60}},
 		},
 		DontPanic: true,
 	}
@@ -187,12 +187,12 @@ func TestNewI2C_calib1(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}, Read: []byte{0x60}},
+			{Addr: 0x76, W: []byte{0xd0}, R: []byte{0x60}},
 			// Calibration data.
 			{
-				Addr:  0x76,
-				Write: []byte{0x88},
-				Read:  []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
+				Addr: 0x76,
+				W:    []byte{0x88},
+				R:    []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
 			},
 		},
 		DontPanic: true,
@@ -210,15 +210,15 @@ func TestNewI2C_calib2(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}, Read: []byte{0x60}},
+			{Addr: 0x76, W: []byte{0xd0}, R: []byte{0x60}},
 			// Calibration data.
 			{
-				Addr:  0x76,
-				Write: []byte{0x88},
-				Read:  []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
+				Addr: 0x76,
+				W:    []byte{0x88},
+				R:    []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
 			},
 			// Calibration data.
-			{Addr: 0x76, Write: []byte{0xe1}, Read: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
+			{Addr: 0x76, W: []byte{0xe1}, R: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
 		},
 		DontPanic: true,
 	}
@@ -257,19 +257,19 @@ func TestI2CSense_fail(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}, Read: []byte{0x60}},
+			{Addr: 0x76, W: []byte{0xd0}, R: []byte{0x60}},
 			// Calibration data.
 			{
-				Addr:  0x76,
-				Write: []byte{0x88},
-				Read:  []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
+				Addr: 0x76,
+				W:    []byte{0x88},
+				R:    []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
 			},
 			// Calibration data.
-			{Addr: 0x76, Write: []byte{0xe1}, Read: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
+			{Addr: 0x76, W: []byte{0xe1}, R: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
 			// Configuration.
-			{Addr: 0x76, Write: []byte{0xf4, 0x6c, 0xf2, 0x3, 0xf5, 0xe0, 0xf4, 0x6f}, Read: nil},
+			{Addr: 0x76, W: []byte{0xf4, 0x6c, 0xf2, 0x3, 0xf5, 0xe0, 0xf4, 0x6f}, R: nil},
 			// Read.
-			{Addr: 0x76, Write: []byte{0xf7}},
+			{Addr: 0x76, W: []byte{0xf7}},
 		},
 		DontPanic: true,
 	}
@@ -292,21 +292,21 @@ func TestI2CSense_success(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Chipd ID detection.
-			{Addr: 0x76, Write: []byte{0xd0}, Read: []byte{0x60}},
+			{Addr: 0x76, W: []byte{0xd0}, R: []byte{0x60}},
 			// Calibration data.
 			{
-				Addr:  0x76,
-				Write: []byte{0x88},
-				Read:  []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
+				Addr: 0x76,
+				W:    []byte{0x88},
+				R:    []byte{0x10, 0x6e, 0x6c, 0x66, 0x32, 0x0, 0x5d, 0x95, 0xb8, 0xd5, 0xd0, 0xb, 0x77, 0x1e, 0x9d, 0xff, 0xf9, 0xff, 0xac, 0x26, 0xa, 0xd8, 0xbd, 0x10, 0x0, 0x4b},
 			},
 			// Calibration data.
-			{Addr: 0x76, Write: []byte{0xe1}, Read: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
+			{Addr: 0x76, W: []byte{0xe1}, R: []byte{0x6e, 0x1, 0x0, 0x13, 0x5, 0x0, 0x1e}},
 			// Configuration.
-			{Addr: 0x76, Write: []byte{0xf4, 0x6c, 0xf2, 0x3, 0xf5, 0xe0, 0xf4, 0x6f}, Read: nil},
+			{Addr: 0x76, W: []byte{0xf4, 0x6c, 0xf2, 0x3, 0xf5, 0xe0, 0xf4, 0x6f}, R: nil},
 			// Read.
-			{Addr: 0x76, Write: []byte{0xf7}, Read: []byte{0x4a, 0x52, 0xc0, 0x80, 0x96, 0xc0, 0x7a, 0x76}},
+			{Addr: 0x76, W: []byte{0xf7}, R: []byte{0x4a, 0x52, 0xc0, 0x80, 0x96, 0xc0, 0x7a, 0x76}},
 			// Stop.
-			{Addr: 0x76, Write: []byte{0xf4, 0x0}},
+			{Addr: 0x76, W: []byte{0xf4, 0x0}},
 		},
 	}
 	dev, err := NewI2C(&bus, nil)
diff --git a/devices/bme280/bme280smoketest/bme280smoketest.go b/devices/bme280/bme280smoketest/bme280smoketest.go
index 524788b..65da9f7 100644
--- a/devices/bme280/bme280smoketest/bme280smoketest.go
+++ b/devices/bme280/bme280smoketest/bme280smoketest.go
@@ -75,15 +75,15 @@ func (s *SmokeTest) Run(args []string) (err error) {
 		fmt.Print("I²C recorder\n")
 	}
 	for _, op := range i2cRecorder.Ops {
-		fmt.Print("  Write: ")
-		for i, b := range op.Write {
+		fmt.Print("  W: ")
+		for i, b := range op.W {
 			if i != 0 {
 				fmt.Print(", ")
 			}
 			fmt.Printf("0x%02X", b)
 		}
-		fmt.Print("\n   Read: ")
-		for i, b := range op.Read {
+		fmt.Print("\n   R: ")
+		for i, b := range op.R {
 			if i != 0 {
 				fmt.Print(", ")
 			}
@@ -93,12 +93,12 @@ func (s *SmokeTest) Run(args []string) (err error) {
 	}
 	fmt.Print("\nSPI recorder\n")
 	for _, op := range spiRecorder.Ops {
-		fmt.Print("  Write: ")
-		if len(op.Read) != 0 {
+		fmt.Print("  W: ")
+		if len(op.R) != 0 {
 			// Read data.
-			fmt.Printf("0x%02X\n   Read: ", op.Write[0])
+			fmt.Printf("0x%02X\n   R: ", op.W[0])
 			// first byte is dummy.
-			for i, b := range op.Read[1:] {
+			for i, b := range op.R[1:] {
 				if i != 0 {
 					fmt.Print(", ")
 				}
@@ -106,13 +106,13 @@ func (s *SmokeTest) Run(args []string) (err error) {
 			}
 		} else {
 			// Write-only command.
-			for i, b := range op.Write {
+			for i, b := range op.W {
 				if i != 0 {
 					fmt.Print(", ")
 				}
 				fmt.Printf("0x%02X", b)
 			}
-			fmt.Print("\n   Read: ")
+			fmt.Print("\n   R: ")
 		}
 		fmt.Print("\n")
 	}
diff --git a/devices/ds18b20/ds18b20_test.go b/devices/ds18b20/ds18b20_test.go
index a434d95..f41bb58 100644
--- a/devices/ds18b20/ds18b20_test.go
+++ b/devices/ds18b20/ds18b20_test.go
@@ -36,18 +36,18 @@ func TestTemperature(t *testing.T) {
 	ops := []onewiretest.IO{
 		// Match ROM + Read Scratchpad (init)
 		{
-			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
-			Read:  []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
+			W: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
+			R: []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
 		},
 		// Match ROM + Convert
 		{
-			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0x44},
-			Pull:  true,
+			W:    []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0x44},
+			Pull: true,
 		},
 		// Match ROM + Read Scratchpad (read temp)
 		{
-			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
-			Read:  []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
+			W: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
+			R: []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
 		},
 	}
 	var addr onewire.Address = 0x740000070e41ac28
@@ -84,7 +84,7 @@ func TestConvertAll(t *testing.T) {
 	// set-up playback using the recording output.
 	ops := []onewiretest.IO{
 		// Skip ROM + Convert
-		{Write: []uint8{0xcc, 0x44}, Read: []uint8(nil), Pull: true},
+		{W: []uint8{0xcc, 0x44}, R: []uint8(nil), Pull: true},
 	}
 	bus := onewiretest.Playback{Ops: ops}
 	// Perform the conversion
diff --git a/devices/ds248x/ds248x_test.go b/devices/ds248x/ds248x_test.go
index a5a34b3..e24963c 100644
--- a/devices/ds248x/ds248x_test.go
+++ b/devices/ds248x/ds248x_test.go
@@ -43,11 +43,11 @@ func Example() {
 func TestNew(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x18, Write: []byte{0xf0}},
-			{Addr: 0x18, Write: []byte{0xe1, 0xf0}, Read: []byte{0x18}},
-			{Addr: 0x18, Write: []byte{0xd2, 0xe1}, Read: []byte{0x1}},
-			{Addr: 0x18, Write: []byte{0xe1, 0xb4}},
-			{Addr: 0x18, Write: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
+			{Addr: 0x18, W: []byte{0xf0}},
+			{Addr: 0x18, W: []byte{0xe1, 0xf0}, R: []byte{0x18}},
+			{Addr: 0x18, W: []byte{0xd2, 0xe1}, R: []byte{0x1}},
+			{Addr: 0x18, W: []byte{0xe1, 0xb4}},
+			{Addr: 0x18, W: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
 		},
 	}
 	d, err := New(&bus, nil)
@@ -65,11 +65,11 @@ func TestNew(t *testing.T) {
 func TestNew_opts(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x18, Write: []byte{0xf0}},
-			{Addr: 0x18, Write: []byte{0xe1, 0xf0}, Read: []byte{0x18}},
-			{Addr: 0x18, Write: []byte{0xd2, 0xe1}, Read: []byte{0x1}},
-			{Addr: 0x18, Write: []byte{0xe1, 0xb4}},
-			{Addr: 0x18, Write: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
+			{Addr: 0x18, W: []byte{0xf0}},
+			{Addr: 0x18, W: []byte{0xe1, 0xf0}, R: []byte{0x18}},
+			{Addr: 0x18, W: []byte{0xd2, 0xe1}, R: []byte{0x1}},
+			{Addr: 0x18, W: []byte{0xe1, 0xb4}},
+			{Addr: 0x18, W: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
 		},
 	}
 	opts := &Opts{Addr: 0x18}
@@ -114,7 +114,7 @@ func TestRecordInit(t *testing.T) {
 	// Output the recording.
 	t.Logf("var ops = i2ctest.IO{\n")
 	for _, op := range i2cBus.Ops {
-		t.Logf("  {Addr: %#x, Write: %#v, Read: %#v},\n", op.Addr, op.Write, op.Read)
+		t.Logf("  {Addr: %#x, W: %#v, R: %#v},\n", op.Addr, op.W, op.R)
 	}
 	t.Logf("}\n")
 }
diff --git a/devices/ssd1306/ssd1306_test.go b/devices/ssd1306/ssd1306_test.go
index 4be8576..c6e12fe 100644
--- a/devices/ssd1306/ssd1306_test.go
+++ b/devices/ssd1306/ssd1306_test.go
@@ -107,9 +107,9 @@ func TestI2C_Draw_VerticalLSD_fast(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Actual draw buffer.
-			{Addr: 0x3c, Write: buf},
+			{Addr: 0x3c, W: buf},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -135,13 +135,13 @@ func TestI2C_Halt_Write(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Halt()
-			{Addr: 0x3c, Write: []byte{0x0, 0xae}},
+			{Addr: 0x3c, W: []byte{0x0, 0xae}},
 			// transparent resume
-			{Addr: 0x3c, Write: []byte{0x0, 0xaf}},
+			{Addr: 0x3c, W: []byte{0x0, 0xaf}},
 			// Actual draw buffer.
-			{Addr: 0x3c, Write: buf},
+			{Addr: 0x3c, W: buf},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -165,9 +165,9 @@ func TestI2C_Halt_resume_fail(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Halt()
-			{Addr: 0x3c, Write: []byte{0x0, 0xae}},
+			{Addr: 0x3c, W: []byte{0x0, 0xae}},
 		},
 		DontPanic: true,
 	}
@@ -190,7 +190,7 @@ func TestI2C_Write_invalid_size(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -209,7 +209,7 @@ func TestI2C_Write_fail(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 		},
 		DontPanic: true,
 	}
@@ -229,7 +229,7 @@ func TestI2C_Draw_fail(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 		},
 		DontPanic: true,
 	}
@@ -250,9 +250,9 @@ func TestI2C_DrawGray(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Actual draw buffer.
-			{Addr: 0x3c, Write: append([]byte{i2cData}, grayCheckboard()...)},
+			{Addr: 0x3c, W: append([]byte{i2cData}, grayCheckboard()...)},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -276,13 +276,13 @@ func TestI2C_DrawGray(t *testing.T) {
 func TestI2C_Scroll(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Scroll Left.
-			{Addr: 0x3c, Write: []byte{0x0, 0x27, 0x0, 0x0, 0x6, 0x7, 0x0, 0xff, 0x2f}},
+			{Addr: 0x3c, W: []byte{0x0, 0x27, 0x0, 0x0, 0x6, 0x7, 0x0, 0xff, 0x2f}},
 			// Scroll UpRight.
-			{Addr: 0x3c, Write: []byte{0x0, 0x29, 0x0, 0x0, 0x6, 0x0, 0x1, 0x2f}},
+			{Addr: 0x3c, W: []byte{0x0, 0x29, 0x0, 0x0, 0x6, 0x0, 0x1, 0x2f}},
 			// StopScroll.
-			{Addr: 0x3c, Write: []byte{0x0, 0x2e}},
+			{Addr: 0x3c, W: []byte{0x0, 0x2e}},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -315,10 +315,10 @@ func TestI2C_Scroll(t *testing.T) {
 func TestI2C_SetContrast(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x3c, Write: initCmdI2C()},
-			{Addr: 0x3c, Write: []byte{0x0, 0x81, 0x0}},
-			{Addr: 0x3c, Write: []byte{0x0, 0x81, 0x7f}},
-			{Addr: 0x3c, Write: []byte{0x0, 0x81, 0xff}},
+			{Addr: 0x3c, W: initCmdI2C()},
+			{Addr: 0x3c, W: []byte{0x0, 0x81, 0x0}},
+			{Addr: 0x3c, W: []byte{0x0, 0x81, 0x7f}},
+			{Addr: 0x3c, W: []byte{0x0, 0x81, 0xff}},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -342,13 +342,13 @@ func TestI2C_SetContrast(t *testing.T) {
 func TestI2C_Invert_Halt_resume(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Invert(true)
-			{Addr: 0x3c, Write: []byte{0x0, 0xa7}},
+			{Addr: 0x3c, W: []byte{0x0, 0xa7}},
 			// Halt()
-			{Addr: 0x3c, Write: []byte{0x0, 0xae}},
+			{Addr: 0x3c, W: []byte{0x0, 0xae}},
 			// transparent resume + Invert(false)
-			{Addr: 0x3c, Write: []byte{0x0, 0xaf, 0xa6}},
+			{Addr: 0x3c, W: []byte{0x0, 0xaf, 0xa6}},
 		},
 	}
 	dev, err := NewI2C(&bus, 128, 64, false)
@@ -372,11 +372,11 @@ func TestI2C_Invert_Halt_resume(t *testing.T) {
 func TestI2C_Halt(t *testing.T) {
 	bus := i2ctest.Playback{
 		Ops: []i2ctest.IO{
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 			// Halt()
-			{Addr: 0x3c, Write: []byte{0x0, 0xae}},
+			{Addr: 0x3c, W: []byte{0x0, 0xae}},
 			// transparent resume + StopScroll()
-			{Addr: 0x3c, Write: []byte{0x0, 0xaf, 0x2e}},
+			{Addr: 0x3c, W: []byte{0x0, 0xaf, 0x2e}},
 		},
 		DontPanic: true,
 	}
@@ -422,7 +422,7 @@ func TestSPI_3wire(t *testing.T) {
 func TestSPI_4wire_String(t *testing.T) {
 	bus := spitest.Playback{
 		Playback: conntest.Playback{
-			Ops: []conntest.IO{{Write: getInitCmd(128, 64, false)}},
+			Ops: []conntest.IO{{W: getInitCmd(128, 64, false)}},
 		},
 	}
 	dev, err := NewSPI(&bus, &gpiotest.Pin{N: "pin1", Num: 42}, 128, 64, false)
@@ -447,11 +447,11 @@ func TestSPI_4wire_Write_differential(t *testing.T) {
 	bus := spitest.Playback{
 		Playback: conntest.Playback{
 			Ops: []conntest.IO{
-				{Write: getInitCmd(128, 64, false)},
-				{Write: buf1},
+				{W: getInitCmd(128, 64, false)},
+				{W: buf1},
 				// Reset to write only to the first page.
-				{Write: []byte{0x21, 0x0, 0x7f, 0x22, 0x1, 0x1}},
-				{Write: buf2},
+				{W: []byte{0x21, 0x0, 0x7f, 0x22, 0x1, 0x1}},
+				{W: buf2},
 			},
 		},
 	}
@@ -479,8 +479,8 @@ func TestSPI_4wire_Write_differential_fail(t *testing.T) {
 	bus := spitest.Playback{
 		Playback: conntest.Playback{
 			Ops: []conntest.IO{
-				{Write: getInitCmd(128, 64, false)},
-				{Write: buf1},
+				{W: getInitCmd(128, 64, false)},
+				{W: buf1},
 			},
 			DontPanic: true,
 		},
@@ -506,9 +506,7 @@ func TestSPI_4wire_Write_differential_fail(t *testing.T) {
 func TestSPI_4wire_gpio_fail(t *testing.T) {
 	bus := spitest.Playback{
 		Playback: conntest.Playback{
-			Ops: []conntest.IO{
-				{Write: getInitCmd(128, 64, false)},
-			},
+			Ops: []conntest.IO{{W: getInitCmd(128, 64, false)}},
 		},
 	}
 	pin := &failPin{fail: false}
@@ -543,7 +541,7 @@ func getI2CPlayback() *i2ctest.Playback {
 	return &i2ctest.Playback{
 		Ops: []i2ctest.IO{
 			// Startup initialization.
-			{Addr: 0x3c, Write: initCmdI2C()},
+			{Addr: 0x3c, W: initCmdI2C()},
 		},
 	}
 }
diff --git a/devices/ssd1306/ssd1306smoketest/ssd1306smoketest.go b/devices/ssd1306/ssd1306smoketest/ssd1306smoketest.go
index 01ada55..ccd06a9 100644
--- a/devices/ssd1306/ssd1306smoketest/ssd1306smoketest.go
+++ b/devices/ssd1306/ssd1306smoketest/ssd1306smoketest.go
@@ -105,15 +105,15 @@ func (s *SmokeTest) Run(args []string) (err error) {
 		fmt.Print("I²C recorder\n")
 	}
 	for _, op := range i2cRecorder.Ops {
-		fmt.Print("  Write: ")
-		for i, b := range op.Write {
+		fmt.Print("  W: ")
+		for i, b := range op.W {
 			if i != 0 {
 				fmt.Print(", ")
 			}
 			fmt.Printf("0x%02X", b)
 		}
-		fmt.Print("\n   Read: ")
-		for i, b := range op.Read {
+		fmt.Print("\n   R: ")
+		for i, b := range op.R {
 			if i != 0 {
 				fmt.Print(", ")
 			}
@@ -123,12 +123,12 @@ func (s *SmokeTest) Run(args []string) (err error) {
 	}
 	fmt.Print("\nSPI recorder\n")
 	for _, op := range spiRecorder.Ops {
-		fmt.Print("  Write: ")
-		if len(op.Read) != 0 {
+		fmt.Print("  W: ")
+		if len(op.R) != 0 {
 			// Read data.
-			fmt.Printf("0x%02X\n   Read: ", op.Write[0])
+			fmt.Printf("0x%02X\n   R: ", op.W[0])
 			// first byte is dummy.
-			for i, b := range op.Read[1:] {
+			for i, b := range op.R[1:] {
 				if i != 0 {
 					fmt.Print(", ")
 				}
@@ -136,13 +136,13 @@ func (s *SmokeTest) Run(args []string) (err error) {
 			}
 		} else {
 			// Write-only command.
-			for i, b := range op.Write {
+			for i, b := range op.W {
 				if i != 0 {
 					fmt.Print(", ")
 				}
 				fmt.Printf("0x%02X", b)
 			}
-			fmt.Print("\n   Read: ")
+			fmt.Print("\n   R: ")
 		}
 		fmt.Print("\n")
 	}