diff --git a/kernel/bio.inc b/kernel/bio.inc
index 32036e8..d768fa3 100644
--- a/kernel/bio.inc
+++ b/kernel/bio.inc
@@ -7,7 +7,7 @@ struc Buffer {
 	.block    dd ?
 	.ulock    dd ?
 	.refcount dd ?
-	.data db 512 dup(?)
+	.data db 1024 dup(?)
 }
 DEFN Buffer
 
diff --git a/kernel/dev/at/ata.inc b/kernel/dev/at/ata.inc
index aece4c8..be25ded 100644
--- a/kernel/dev/at/ata.inc
+++ b/kernel/dev/at/ata.inc
@@ -14,9 +14,26 @@ ATA_CHAN1_IO = 0x170
 ATA_CHAN2_IO = 0x1E8
 ATA_CHAN3_IO = 0x168
 
+	;; Constant:  ATA_DATA
+	;; Read/Write data
 ATA_DATA     = 0x0
+
 	;; Constant: ATA_ERROR
 	;;
+	;; > ┌────┬─────┬────┬───┬────┬──┬───┬───┐
+    ;; > │AMNF│TKZNF│ABRT│MCR│IDNF│MC│UNC│BBK│
+    ;; > └────┴─────┴────┴───┴────┴──┴───┴───┘
+    ;; >      7     6    5   4    3  2   1   0
+	;;
+	;; AMNF  - Address mark not found.
+	;; TKZNF - Track zero not found.
+	;; ABRT  - Aborted command.
+	;; MCR   - Media change request.
+	;; IDNF  - ID not found.
+	;; MC    - Media changed
+	;; UNC   - Uncorrectable data error.
+	;; BBK   - Bad Block detected.
+	;;
 ATA_ERROR    = 0x1
 ATA_ERROR_AMNF  = 0x01
 ATA_ERROR_TKZNF = 0x02
@@ -27,11 +44,21 @@ ATA_ERROR_MC    = 0x20
 ATA_ERROR_UNC   = 0x40
 ATA_ERROR_BBK   = 0x80
 
+	;; Constant: ATA_FEATURES
 ATA_FEATURES = 0x1
+
+	;; Constant: ATA_SECCOUNT
 ATA_SECCOUNT = 0x2
+
+	;; Constant: ATA_SECNUM
 ATA_SECNUM   = 0x3
+
+	;; Constant: ATA_CYLLO
 ATA_CYLLO    = 0x4
+
+	;; Constant: ATA_CYLHI
 ATA_CYLHI    = 0x5
+
 	;; Constant: ATA_DRVHEAD
 	;; Drive/Head register
 	;;
@@ -39,8 +66,18 @@ ATA_DRVHEAD  = 0x6
 ATA_DRVHEAD_DRV = 0x10
 ATA_DRVHEAD_LBA = 0x40
 
+	;; Constant: ATA_COMMAND
 ATA_COMMAND  = 0x7
 
+	;; Constant: ATA_CMD_RESTORE
+	;; Recalibrate
+ATA_CMD_RESTORE    = 0x10
+	;; Constant: ATA_CMD_DIAGNOSTIC
+	;; Execute device diagnostic
+ATA_CMD_DIAGNOSTIC = 0x90
+	;; Constant: ATA_CMD_IDENTIFY
+ATA_CMD_IDENTIFY   = 0xA0
+
 	;; Constant: ATA_STATUS
 	;; 
 ATA_STATUS   = 0x7
@@ -60,14 +97,13 @@ ATA_CTRL_nIEN = 0x02
 ATA_CTRL_SRST = 0x04
 ATA_CTRL_HOB  = 0x80
 
+	;; Constant: ATA_DRVADDR
+	;; 
 ATA_DRVADDR = 0x1
 ATA_DRVADDR_DS0 = 0x01
 ATA_DRVADDR_DS1 = 0x02
 ATA_DRVADDR_WTG = 0x40
 
-ATA_CMD_RESTORE    = 0x10
-ATA_CMD_DIAGNOSTIC = 0x90
-ATA_CMD_IDENTIFY   = 0xA0
 
 	;; Function: ata_wait
 	;;
@@ -88,6 +124,7 @@ ata_wait:
 @@:
 	ret
 
+	;; Function: ata_select
 ata_select:
 	ret
 
@@ -215,4 +252,7 @@ aAtaChans:
 	dw ATA_CHAN3_IO
 .end:
 
+ata_bdevsw:
+	dd 0
+
 szMsgAtaFound db "ATA: hd%u found", 0
diff --git a/kernel/dev/dev.inc b/kernel/dev/dev.inc
index 0d7d0a5..2dd487a 100644
--- a/kernel/dev/dev.inc
+++ b/kernel/dev/dev.inc
@@ -15,6 +15,14 @@ struc Device {
 }
 DEFN Device
 
+	;; Struc: BlkDev
+	;;
+	;; .open     - Open the device in preparation for I/O operations
+	;; .strategy - Start a read or write operation, and return immediately.
+	;; .close    - Close a device.
+	;; .dump     - Write all physical memory to the device.
+	;; .psize    - Return the size of a disk-drive partition.
+	;;
 struc BlkDev {
 	.open     dd ?
 	.strategy dd ?
@@ -24,6 +32,18 @@ struc BlkDev {
 	.psize    dd ?
 }
 
+	;; Struc: CharDev
+	;;
+	;; .open   - open the device.
+	;; .close  - close the device..
+	;; .read   - do an input operation.
+	;; .write  - do an output operation.
+	;; .ioctl  - do an I/O control operation.
+	;; .select - poll device for I/O readiness.
+	;; .stop   - stop output on the device.
+	;; .mmap   - map device offset to memory location
+	;; .reset  - reinitialize device after a bus reset.
+	;;
 struc CharDev {
 	.open   dd ?
 	.close  dd ?
@@ -38,6 +58,7 @@ struc CharDev {
 
 aBlockDevices:
 	dd floppy_bdevsw
+	dd ata_bdevsw
 .end:
 
 aCharDevices:
@@ -54,6 +75,7 @@ aDevices:
 	dd ata_device
 .end:
 
+	;; Function: dev_init
 dev_init:
 	mov ecx, aDevices
 @@: