diff --git a/cmd_parser.c b/cmd_parser.c
index ef06898..a7d03d7 100644
--- a/cmd_parser.c
+++ b/cmd_parser.c
@@ -428,7 +428,7 @@ void cmd_parser(void) __banked
 
 		if (cmd_compare(0, "gpio")) {
 			for (uint8_t idx = 0; idx < 3; idx++) {
-				reg_read(RTL837X_REG_GPIO_A + (idx * 4));
+				reg_read(RTL837X_REG_GPIO_32_63_OUTPUT + (idx * 4));
 				print_string("GPIO ");
 				write_char(idx + 'A');
 				write_char(':');
diff --git a/rtl837x_port.c b/rtl837x_port.c
index f999196..4383bf0 100644
--- a/rtl837x_port.c
+++ b/rtl837x_port.c
@@ -423,13 +423,13 @@ void port_stats_print(void) __banked
 				break;
 			}
 		} else {  // An SFP Module TODO: This is for 1 module devices
-			reg_read_m(RTL837X_REG_GPIO_B);
+			reg_read_m(RTL837X_REG_GPIO_00_31_INPUT);
 			if (!(sfr_data[0] & 0x40)) {
 				print_string("SFP OK\t");
 			} else {
 				print_string("NO SFP\t");
 			}
-			reg_read_m(RTL837X_REG_GPIO_C);
+			reg_read_m(RTL837X_REG_GPIO_32_63_INPUT);
 			if (sfr_data[3] & 0x20) {
 				print_string("Down\t");
 			} else {
diff --git a/rtl837x_regs.h b/rtl837x_regs.h
index a07f2be..58b09b7 100644
--- a/rtl837x_regs.h
+++ b/rtl837x_regs.h
@@ -44,19 +44,24 @@
  * Pin configuration (pinmux)
  */
 
-#define RTL837X_PIN_MUX_A	0x7f8c
-#define RTL837X_PIN_MUX_B	0x7f90
+#define RTL837X_PIN_MUX_0	0x7f8c
+#define RTL837X_PIN_MUX_1	0x7f90
 
-#define RTL837X_REG_GPIO_A 0x40
+// Output Registers
+#define RTL837X_REG_GPIO_00_31_OUTPUT 0x3c
+#define RTL837X_REG_GPIO_32_63_OUTPUT 0x40
 // BIT 4 resets RTL8224 on 9000-9XH
 
-#define RTL837X_REG_GPIO_B 0x44
+// Input Registers
+#define RTL837X_REG_GPIO_00_31_INPUT 0x44
+#define RTL837X_REG_GPIO_32_63_INPUT 0x48
 // Bit 1e cleared: SFP Module inserted on 9000-6XH (MOD_DEF0 pin)
 
-#define RTL837X_REG_GPIO_C 0x48
 // BIT 5 set: SIGNAL LOS of SFP module on 9000-6XH (RX_LOS pin)
 
-#define RTL837X_REG_GPIO_CONF_A 0x50
+// Direction Registers, 0 = input, 1 = output
+#define RTL837X_REG_GPIO_00_31_DIRECTION 0x4c
+#define RTL837X_REG_GPIO_32_63_DIRECTION 0x50
 // Configures IO direction for bank a
 
 #define RTL837X_REG_GPIO_EXT 0x63e8
diff --git a/rtlplayground.c b/rtlplayground.c
index c140362..dcff1f9 100644
--- a/rtlplayground.c
+++ b/rtlplayground.c
@@ -873,7 +873,7 @@ void sfp_print_info(uint8_t sfp)
 
 void handle_sfp(void)
 {
-	reg_read_m(RTL837X_REG_GPIO_B);
+	reg_read_m(RTL837X_REG_GPIO_00_31_INPUT);
 	if ((sfp_pins_last & 0x1) && (!(sfr_data[0] & 0x40))) {
 		sfp_pins_last &= ~0x01;
 		print_string("\n<MODULE INSERTED>  ");
@@ -893,7 +893,7 @@ void handle_sfp(void)
 		print_string("\n<MODULE REMOVED>\n");
 	}
 
-	reg_read_m(RTL837X_REG_GPIO_C);
+	reg_read_m(RTL837X_REG_GPIO_32_63_INPUT);
 	if ((sfp_pins_last & 0x2) && (!(sfr_data[3] & 0x20))) {
 		sfp_pins_last &= ~0x02;
 		print_string("\n<SFP-RX OK>\n");
@@ -903,7 +903,7 @@ void handle_sfp(void)
 		print_string("\n<SFP-RX LOS>\n");
 	}
 
-	reg_read_m(RTL837X_REG_GPIO_C);
+	reg_read_m(RTL837X_REG_GPIO_32_63_INPUT);
 	if ((sfp_pins_last & 0x10) && (!(sfr_data[1] & 0x04))) {
 		sfp_pins_last &= ~0x10;
 		print_string("\n<MODULE 2 INSERTED>  ");
@@ -989,7 +989,7 @@ void idle(void)
 	handle_sfp();
 
 	/* Button pressed on KL-8xhm-x2:
-	reg_read(RTL837X_REG_GPIO_C);
+	reg_read(RTL837X_REG_GPIO_32_63_INPUT);
 	if (!(sfr_data[2] & 0x40))
 		print_string("Button pressed\n");
 	*/
@@ -1038,12 +1038,12 @@ void setup_external_irqs(void)
 void rtl8224_enable(void)
 {
 	// Set Pin 4 low
-	reg_bit_clear(RTL837X_REG_GPIO_A, 4);
+	reg_bit_clear(RTL837X_REG_GPIO_32_63_OUTPUT, 4);
 	// Configure Pin as output
-	reg_bit_set(RTL837X_REG_GPIO_CONF_A, 4);
+	reg_bit_set(RTL837X_REG_GPIO_32_63_DIRECTION, 4);
 	delay(100);
 	// Set pin 4 high
-	reg_bit_set(RTL837X_REG_GPIO_A, 4);
+	reg_bit_set(RTL837X_REG_GPIO_32_63_OUTPUT, 4);
 	delay(500);
 }
 
@@ -1064,9 +1064,9 @@ void setup_clock(void)
 	reg_write_m(RTL837X_REG_HW_CONF);
 
 	// Enable serial interface, set bit 0
-	reg_read_m(RTL837X_PIN_MUX_B);
+	reg_read_m(RTL837X_PIN_MUX_1);
 	sfr_mask_data(0, 0x1, 0x1);
-	reg_write_m(RTL837X_PIN_MUX_B);
+	reg_write_m(RTL837X_PIN_MUX_1);
 }
 
 
@@ -1286,7 +1286,7 @@ void led_config_9xh(void)
 	reg_bit_clear(0x65dc, 0x1b);
 
 	// r7f8c:30000000 R7f8c-30000000 r7f8c:30000000 R7f8c-38000000
-	reg_bit_set(RTL837X_PIN_MUX_A, 0x1b);
+	reg_bit_set(RTL837X_PIN_MUX_0, 0x1b);
 
 	// R6548-0041017f
 	REG_SET(0x6548, 0x0041017f);
@@ -1338,13 +1338,13 @@ void led_config(void)
 
 	// Set bits 1b/1d of 0x7f8c: r7f8c:30000000 R7f8c-30000000 r7f8c:30000000 R7f8c-38000000
 	if (nSFPPorts == 2) {
-		reg_bit_set(RTL837X_PIN_MUX_A, 0x1b); // R7f8c-28000000
-		reg_bit_clear(RTL837X_PIN_MUX_A, 0x1c); // R7f8c-28000000
-		reg_bit_set(RTL837X_PIN_MUX_A, 0x1d); // R7f8c-28000000
+		reg_bit_set(RTL837X_PIN_MUX_0, 0x1b); // R7f8c-28000000
+		reg_bit_clear(RTL837X_PIN_MUX_0, 0x1c); // R7f8c-28000000
+		reg_bit_set(RTL837X_PIN_MUX_0, 0x1d); // R7f8c-28000000
 	} else {
-		reg_bit_set(RTL837X_PIN_MUX_A, 0x1d);
-		reg_bit_set(RTL837X_PIN_MUX_A, 0x1c);
-		reg_bit_set(RTL837X_PIN_MUX_A, 0x1b);
+		reg_bit_set(RTL837X_PIN_MUX_0, 0x1d);
+		reg_bit_set(RTL837X_PIN_MUX_0, 0x1c);
+		reg_bit_set(RTL837X_PIN_MUX_0, 0x1b);
 	}
 	// LED setup
 	// r6520:0021fdb0 R6520-0021e7b0 r6520:0021e7b0 R6520-0021e6b0 r65f8:00000018 R65f8-00000018 R65fc-fffff000 r6600:00000000 R6600-0000000f r65dc:5fffff00 R65dc-7fffff00 r65dc:7fffff00 R65dc-77ffff00
@@ -1620,10 +1620,10 @@ void setup_i2c(void)
 	REG_SET(0x041c, 0);
 
 	// HW Control register, enable I2C?
-	reg_read_m(RTL837X_PIN_MUX_B);
+	reg_read_m(RTL837X_PIN_MUX_1);
 	sfr_mask_data(3, 0x20, 0x00); // Clear bit 29
 	sfr_mask_data(0, 0x60, 0x40); // Set bits 5-6 to 0b10
-	reg_write_m(RTL837X_PIN_MUX_B);
+	reg_write_m(RTL837X_PIN_MUX_1);
 }