diff --git a/kernel/ata.c b/kernel/ata.c
index 181503e..20ddd12 100644
--- a/kernel/ata.c
+++ b/kernel/ata.c
@@ -12,9 +12,22 @@ static inline void ata_delay(void) {
     inb(ATA_PRIMARY_CTRL);
 }
 
+bool ata_wait_ready(void) {
+    for (int i = 0; i < ATA_TIMEOUT; i++) {
+        uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+        /* Must NOT be busy AND must be ready */
+        if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRDY))
+            return true;
+    }
+    return false;
+}
+
 static bool ata_wait(uint8_t mask) {
     for (int i = 0; i < ATA_TIMEOUT; i++) {
         uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+        /* If ERR is set, stop waiting and return failure */
+        if (status & ATA_SR_ERR) return false;
+        
         if (!(status & ATA_SR_BSY) && (status & mask))
             return true;
     }
@@ -22,16 +35,17 @@ static bool ata_wait(uint8_t mask) {
 }
 
 bool ata_init(void) {
-    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xA0); // master
+    /* Select drive */
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, ATA_MASTER);
     ata_delay();
 
+    /* Check if drive exists */
+    uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+    if (status == 0xFF || status == 0) return false;
+
     outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_IDENTIFY);
     ata_delay();
 
-    uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
-    if (status == 0)
-        return false; // no drive
-
     if (!ata_wait(ATA_SR_DRQ))
         return false;
 
@@ -46,20 +60,28 @@ bool ata_init(void) {
 bool ata_read_sector(uint32_t lba, uint8_t* buffer) {
     if (!buffer) return false;
 
+    /* 1. Wait for drive to be ready for command */
+    if (!ata_wait_ready()) return false;
+
+    /* 2. Setup Task File (LBA28) */
     outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
     outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
     outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
     outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
     outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
+    
+    /* 3. Issue Read Command */
     outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
 
+    /* 4. Wait for Data Request (DRQ) */
     if (!ata_wait(ATA_SR_DRQ))
         return false;
 
+    /* 5. Transfer data */
     for (int i = 0; i < 256; i++) {
         uint16_t data = inw(ATA_PRIMARY_IO);
         buffer[i * 2]     = data & 0xFF;
-        buffer[i * 2 + 1] = data >> 8;
+        buffer[i * 2 + 1] = (data >> 8) & 0xFF;
     }
 
     ata_delay();
@@ -69,20 +91,26 @@ bool ata_read_sector(uint32_t lba, uint8_t* buffer) {
 bool ata_write_sector(uint32_t lba, const uint8_t* buffer) {
     if (!buffer) return false;
 
+    /* 1. Wait for drive to be ready for command */
+    if (!ata_wait_ready()) return false;
+
+    /* 2. Setup Task File */
     outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
     outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
     outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
     outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
     outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
+    
+    /* 3. Issue Write Command */
     outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_WRITE_PIO);
 
+    /* 4. Wait for drive to request data */
     if (!ata_wait(ATA_SR_DRQ))
         return false;
 
+    /* 5. Transfer data */
     for (int i = 0; i < 256; i++) {
-        uint16_t word =
-            buffer[i * 2] |
-            (buffer[i * 2 + 1] << 8);
+        uint16_t word = buffer[i * 2] | (buffer[i * 2 + 1] << 8);
         outw(ATA_PRIMARY_IO, word);
     }