Implement reading geometry info from floppy BPB

kernel/diskio.asm

@@ -65,6 +65,10 @@ select_floppy:
 	xor ax, ax
 	call seek
 	call read
+	mov ax, [disk_buffer+0x0B+bpb_spt]
+	mov [disk_spt], ax
+	mul word [disk_buffer+0x0B+bpb_nos]
+	mov [disk_tracks], ax
 	ret
 
 	; Set absolute sector number
@@ -84,14 +88,13 @@ seek:	push ax
 	ror dl, 1
 	ror dl, 1
 	or dl, ah
-	;inc dx
+	inc dx
 	; dh bit 0-7: cylinder 0-7
 	; dl bit 0-5: sector number 0-5
 	; dl bit 6-7: cylinder 8-9
 	; store
 	mov byte [disk_chs+1], al
 	mov word [disk_chs+2], dx
-	int 3
 	ret
 
 seek_zero:
@@ -106,11 +109,9 @@ read:	mov ax, 0x0201
 	lea bx, [disk_buffer]
 	push cs
 	pop es
-	int 3
 	int 0x13
-	int 3
 	ret
 
 	; Write a sector into buffer
-write:
+write:	stc
 	ret