Add a disk description table to the bootloader in anticipation of file system support and do some general tweaking.

make.sh

@@ -6,9 +6,9 @@ then
 fi
 
 cd src/
-nasm boot.asm -f bin -o ../build/boot.bin
+nasm boot.asm -f bin -O0 -o ../build/boot.bin
-nasm os.asm -f bin -o ../build/os.bin
+nasm system.asm -f bin -O0 -o ../build/system.bin
 
 cd ../build/
-cat boot.bin os.bin > EttinOS.img
+cat boot.bin system.bin > EttinOS.img
-rm boot.bin os.bin
+rm boot.bin system.bin

src/boot.asm

@@ -1,5 +1,26 @@
 [ORG 0x7c00]
 jmp 0:start
+nop
+
+;Disk description table
+db "EttinOS "    ;Disk label
+dw 0x200         ;Bytes per sector
+db 0x1           ;Sectors per cluster
+dw 0x1           ;Sectors reserved for the boot record
+db 0x2           ;Number of copies of the FAT
+dw 0xe0          ;Number of directory entries
+dw 0xb40         ;Number of logical sectors
+db 0xf0          ;Media descriptor type
+dw 0x9           ;Sectors per FAT
+dw 0x12          ;Sectors per track
+dw 0x2           ;Number of heads
+dd 0x0           ;Number of hidden sectors
+dd 0x0           ;Number of LBA sectors
+dw 0x0           ;Drive number
+db 0x29          ;Drive signature
+dd 0x0           ;Volume ID
+db "EttinOS    " ;Volume label
+db "FAT12   "    ;File system type
 
 start:
 
@@ -7,6 +28,7 @@ start:
 mov ax, 0x0
 mov ds, ax
 
+;Load the system
 ;Set the source
 mov dh, 0x0
 mov ch, 0x0
@@ -21,7 +43,7 @@ mov al, 0x20
 mov ah, 0x2
 int 0x13
 
-;Boot
+;Boot the system
 jmp 0x1000:0
 
 ;Padding

src/echo.inc

@@ -5,7 +5,7 @@ echo:
 ;Read a string
 mov di, buffer
 mov al, 0xff
-call readstr
+call readln
 
 ;Check for an empty string
 cmp byte [buffer], 0x0

src/keycode.inc

@@ -1,4 +1,4 @@
-;Reads a keypress and prints its keycode.
+;Reads a keypress and prints its BIOS code.
 
 keycode:
 

src/newline.inc

@@ -0,0 +1,11 @@
+;Prints a newline
+
+newline:
+
+mov si, .newline
+call printstr
+
+ret
+
+.newline:
+db 0xd, 0xa, 0x0

src/println.inc

@@ -1,14 +1,11 @@
-;Prints a line from si until a null.
+;Prints a string from si until a null followed by a newline.
+
 println:
 
-;Print a string
+;Print the string
 call printstr
 
 ;Print a newline
-mov si, .newline
+call newline
-call printstr
 
 ret
-
-.newline:
-db 0xd, 0xa, 0x0

src/readln.inc

@@ -1,6 +1,6 @@
-;Reads a string of at most al characters to di.
+;Reads a string of at most al characters to di until a return and prints a newline.
 
-readstr:
+readln:
 
 ;Store the length
 mov [.length], al
@@ -161,8 +161,7 @@ mov ah, 0x2
 mov dh, [.lastln]
 int 0x10
 ;Print a newline
-mov si, .newline
+call newline
-call printstr
 
 ret
 
@@ -174,6 +173,3 @@ db 0x0
 
 .lastln:
 db 0x0
-
-.newline:
-db 0xd, 0xa, 0x0

src/system.asm

@@ -3,7 +3,8 @@ jmp start
 ;Calls
 %include "printstr.inc"
 %include "println.inc"
-%include "readstr.inc" ;Under construction
+%include "readln.inc"
+%include "newline.inc"
 %include "cmpstr.inc"
 %include "byte2hexstr.inc"
 
@@ -37,48 +38,55 @@ call printstr
 ;Read a command
 mov di, buffer
 mov al, 0xff
-call readstr
+call readln
 
 exec:
-;No command
+;Identify and execute the command
+
+;Check for no command
 cmp byte [buffer], 0x0
 je loop
+
 .echo:
-;Check for the command
+;Check
 mov si, buffer
 mov di, cmd.echo
 call cmpstr
 jnc .hello
-;Execute the command
+;Execute
 call echo
 jmp loop
+
 .hello:
-;Check for the command
+;Check
 mov si, buffer
 mov di, cmd.hello
 call cmpstr
 jnc .help
-;Execute the command
+;Execute
 call hello
 jmp loop
+
 .help:
-;Check for the command
+;Check
 mov si, buffer
 mov di, cmd.help
 call cmpstr
 jnc .keycode
-;Execute the command
+;Execute
 call help
 jmp loop
+
 .keycode:
-;Check for the command
+;Check
 mov si, buffer
 mov di, cmd.keycode
 call cmpstr
 jnc .error
-;Execute the command
+;Execute
 call keycode
 jmp loop
+
 .error:
 mov si, error
 call println