diff --git a/SOURCE/BOOT.ASM b/SOURCE/BOOT.ASM
index f80d4fe..d856c6c 100644
--- a/SOURCE/BOOT.ASM
+++ b/SOURCE/BOOT.ASM
@@ -1,26 +1,54 @@
-[ORG 0x7c00]
+CPU 8086
+ORG 0x7c00
+
 jmp start
 nop
 
-;1.44 MB 3.5" floppy disk description table
-OEMLabel          db "ETTINOS "
-BytesPerSector    dw 0x200
-SectorsPerCluster db 0x1
-BootRecordSectors dw 0x1
-FATs              db 0x2
-RootEntries       dw 0xe0
-LogicalSectors    dw 0xb40
-MediaDescriptor   db 0xf0
-SectorsPerFAT     dw 0x9
-SectorsPerTrack   dw 0x12
-Sides             dw 0x2
-HiddenSectors     dd 0x0
-LargeSectors      dd 0x0
-DriveNumber       dw 0x0
-DriveSignature    db 0x29
-VolumeID          dd 0x0
-VolumeLabel       db "ETTINOS    "
-FileSystem        db "FAT12   "
+;Disk description tables
+
+%ifdef F1440
+;1.44 MB 3.5" floppy disk (enable by passing -d F1440 to NASM)
+oemlabel        db "ETTINOS "
+sectorsize      dw 0x200 ;bytes
+clustersize     db 0x1 ;sectors
+bootsectors     dw 0x1
+fats            db 0x2
+rootentries     dw 0xe0
+logicalsectors  dw 0xb40
+mediadescriptor db 0xf0
+sectorsperfat   dw 0x9
+sectorspertrack dw 0x12
+sides           dw 0x2
+hiddensectors   dd 0x0
+largesectors    dd 0x0
+driveid         dw 0x0
+drivesignature  db 0x29
+volumeid        dd 0x0
+volumelabel     db "ETTINOS    "
+filesystem      db "FAT12   "
+
+%else
+;360 KiB 5.25" floppy disk (default)
+oemlabel        db "ETTINOS "
+sectorsize      dw 0x200 ;bytes
+clustersize     db 0x2 ;sectors
+bootsectors     dw 0x1
+fats            db 0x2
+rootentries     dw 0x70
+logicalsectors  dw 0x2d0
+mediadescriptor db 0xfd
+sectorsperfat   dw 0x2
+sectorspertrack dw 0x9
+sides           dw 0x2
+hiddensectors   dd 0x0
+largesectors    dd 0x0
+driveid         dw 0x0
+drivesignature  db 0x29
+volumeid        dd 0x0
+volumelabel     db "ETTINOS    "
+filesystem      db "FAT12   "
+
+%endif
 
 start:
 
@@ -38,9 +66,13 @@ sti
 ;Store the boot device number
 mov [bootdev], dl
 
-;Load the root FAT
+;Load the root
 ;Set the source
-mov ax, 0x13
+mov ah, 0x0
+mov al, [fats]
+mul word [sectorsperfat]
+add ax, [bootsectors]
+push ax
 call calcsource
 ;Set the destination
 mov si, 0x7e00
@@ -48,18 +80,25 @@ mov bx, ds
 mov es, bx
 mov bx, si
 ;Set the size
-mov al, 0xe
+push dx
+mov ax, [rootentries]
+mov dx, 0x20
+mul dx
+mov dx, 0x0
+div word [sectorsize]
+pop dx
+push ax
 ;Load
 mov ah, 0x2
 int 0x13
 
-;Search the root FAT for the system FAT
+;Search the root for the system
 ;Set DI to the root FAT
 mov ax, ds
 mov es, ax
 mov di, 0x7e00
 ;Initialise the search loop
-mov cx, word [RootEntries]
+mov cx, word [rootentries]
 mov ax, 0x0
 search:
 ;Store CX in the stack
@@ -68,7 +107,7 @@ push cx
 mov si, sysfile
 mov cx, 0xb
 rep cmpsb
-je loadsysfat
+je loadfat
 ;Set DI to the next entry
 add ax, 0x20
 mov di, 0x7e00
@@ -78,7 +117,9 @@ pop cx
 loop search
 
 ;Load the system FAT
-loadsysfat:
+loadfat:
+;Load CX from the stack
+pop cx
 ;Store the first cluster
 mov ax, word [es:di+0xf]
 mov word [cluster], ax
@@ -89,16 +130,23 @@ call calcsource
 mov di, 0x7e00
 mov bx, di
 ;Set the size
-mov al, 0x9
+mov ax, [sectorsperfat]
 ;Load
 mov ah, 0x2
 int 0x13
 
-;Load the system
-loadsys:
+;Load the system file
+
+;Load a cluster
+loadcluster:
 ;Set the source
-mov ax, word [cluster]
-add ax, 0x1f
+pop bx
+pop ax
+push ax
+push bx
+add ax, bx
+sub ax, 0x2
+add ax, word [cluster]
 call calcsource
 ;Set the destination
 mov ax, 0x0
@@ -106,7 +154,7 @@ mov es, ax
 mov bx, word [pointer]
 ;Set the size
 mov al, 0x1
-;Load a cluster
+;Load
 mov ah, 0x2
 int 0x13
 
@@ -115,7 +163,7 @@ mov ax, [cluster]
 mov dx, 0x0
 mov bx, 0x3
 mul bx
-mov bx, 2
+mov bx, 0x2
 div bx
 mov si, 0x7e00
 add si, ax
@@ -123,45 +171,43 @@ mov ax, word [ds:si]
 or dx, dx
 jz even
 odd:
-shr ax, 4
-jmp contcluster
+shr ax, 1
+shr ax, 1
+shr ax, 1
+shr ax, 1
+jmp contcalc
 even:
 and ax, 0xfff
-contcluster:
+contcalc:
 mov word [cluster], ax
 cmp ax, 0xff8
 jge boot
 add word [pointer], 0x200
-jmp loadsys
+jmp loadcluster
 
 boot:
 jmp 0x0:0x9e00
 
-sysfile:
-db "SYSTEM  BIN"
+sysfile db "SYSTEM  BIN"
 
-bootdev:
-db 0
+bootdev db 0x0
 
-cluster:
-dw 0x0
-
-pointer:
-dw 0x9e00
+cluster dw 0x0
+pointer dw 0x9e00
 
 calcsource:
 push ax
 push bx
 mov bx, ax
 mov dx, 0x0
-div word [SectorsPerTrack]
+div word [sectorspertrack]
 add dl, 0x1
 mov cl, dl
 mov ax, bx
 mov dx, 0x0
-div word [SectorsPerTrack]
+div word [sectorspertrack]
 mov dx, 0x0
-div word [Sides]
+div word [sides]
 mov dh, dl
 mov ch, al
 pop bx
diff --git a/SOURCE/BYTE2HEX.INC b/SOURCE/BYTE2HEX.INC
index 655d346..78a6ac1 100644
--- a/SOURCE/BYTE2HEX.INC
+++ b/SOURCE/BYTE2HEX.INC
@@ -1,9 +1,15 @@
-;Converts a byte in AH to a hex string at DI.
+;Converts a byte in AL to a hex string at DI.
 
 byte2hex:
 
 ;Store the initial registers in the stack
-pusha
+push si
+push ax
+push bx
+push cx
+
+;Move the byte to AH
+mov ah, al
 
 ;Set a key for the hex digits
 mov si, .key
@@ -14,7 +20,10 @@ mov cx, 0x2
 .loop:
 
 ;Read a nibble
-rol ax, 0x4
+rol ax, 0x1
+rol ax, 0x1
+rol ax, 0x1
+rol ax, 0x1
 mov bx, ax
 
 ;Convert the nibble to a hex digit
@@ -30,9 +39,11 @@ dec cx
 jnz .loop
 
 ;Load the initial registers from the stack
-popa
+pop cx
+pop bx
+pop ax
+pop si
 
 ret
 
-.key:
-db "0123456789abcdef"
+.key db "0123456789abcdef"
diff --git a/SOURCE/CMPSTR.INC b/SOURCE/CMPSTR.INC
index 0eef00d..014cdda 100644
--- a/SOURCE/CMPSTR.INC
+++ b/SOURCE/CMPSTR.INC
@@ -1,9 +1,10 @@
-;Compares strings from SI and SI and sets the carry flag if they are equal and clears it if not.
+;Compares strings from SI and DI until a null and either sets the carry flag if they are equal or clears it if not.
 
 cmpstr:
 
 ;Store the initial registers in the stack
-pusha
+push ax
+push bx
 
 .loop:
 
@@ -38,6 +39,7 @@ stc
 .done:
 
 ;Load the initial registers from the stack
-popa
+pop bx
+pop ax
 
 ret
diff --git a/SOURCE/HELLO.INC b/SOURCE/HELLO.INC
index 1dc1afc..b3f7133 100644
--- a/SOURCE/HELLO.INC
+++ b/SOURCE/HELLO.INC
@@ -7,5 +7,4 @@ call println
 
 ret
 
-.hello:
-db "Hello world!", 0x0
\ No newline at end of file
+.hello db "Hello world!", 0x0
\ No newline at end of file
diff --git a/SOURCE/HELP.INC b/SOURCE/HELP.INC
index 02311f1..a8abcb8 100644
--- a/SOURCE/HELP.INC
+++ b/SOURCE/HELP.INC
@@ -7,5 +7,4 @@ call println
 
 ret
 
-.help:
-db "Input:", 0xd, 0xa, "* Typing a character overwrites the cursor location.", 0xd, 0xa, "* The erase (=tab) key erases the cursor location.", 0xd, 0xa, "* The space and backspace keys move the cursor.", 0xd, 0xa, "Commands:", 0xd, 0xa, "* echo: echoes its input.", 0xd, 0xa, "* hello: a hello world program.", 0xd, 0xa, "* help: you are reading it.", 0xd, 0xa, "* keycode: echoes the BIOS code of a key.", 0x0
+.help db "Input:", 0xd, 0xa, "* Typing a character overwrites the cursor location.", 0xd, 0xa, "* The erase (=tab) key erases the cursor location.", 0xd, 0xa, "* The space and backspace keys move the cursor.", 0xd, 0xa, "Commands:", 0xd, 0xa, "* echo: echoes its input.", 0xd, 0xa, "* hello: a hello world program.", 0xd, 0xa, "* help: you are reading it.", 0xd, 0xa, "* keycode: echoes the BIOS code of a key.", 0x0
diff --git a/SOURCE/KEYCODE.INC b/SOURCE/KEYCODE.INC
index fdfb321..e056e7e 100644
--- a/SOURCE/KEYCODE.INC
+++ b/SOURCE/KEYCODE.INC
@@ -15,12 +15,12 @@ mov si, .prefix
 call printstr
 
 ;Convert the scancode to a hex string
-mov ah, [.scan]
+mov al, [.scan]
 mov di, .keycode
 call byte2hex
 
 ;Convert the ascii value to a hex string
-mov ah, [.ascii]
+mov al, [.ascii]
 mov di, .keycode
 add di, 0x2
 call byte2hex
@@ -31,14 +31,9 @@ call println
 
 ret
 
-.prefix:
-db "0x", 0x0
+.prefix db "0x", 0x0
 
-.scan:
-db 0x0
+.scan db 0x0
+.ascii db 0x0
 
-.ascii:
-db 0x0
-
-.keycode:
-times 0x5 db 0x0
+.keycode times 0x5 db 0x0
diff --git a/SOURCE/PRINTNL.INC b/SOURCE/PRINTNL.INC
index 9d603db..481073f 100644
--- a/SOURCE/PRINTNL.INC
+++ b/SOURCE/PRINTNL.INC
@@ -3,16 +3,15 @@
 printnl:
 
 ;Store the initial registers in the stack
-pusha
+push si
 
 ;Print the newline
 mov si, .nl
 call printstr
 
 ;Load the initial registers from the stack
-popa
+pop si
 
 ret
 
-.nl:
-db 0xd, 0xa, 0x0
+.nl db 0xd, 0xa, 0x0
diff --git a/SOURCE/PRINTSTR.INC b/SOURCE/PRINTSTR.INC
index 1ba6070..7f3af5c 100644
--- a/SOURCE/PRINTSTR.INC
+++ b/SOURCE/PRINTSTR.INC
@@ -3,7 +3,7 @@
 printstr:
 
 ;Store the initial registers in the stack
-pusha
+push ax
 
 .loop:
 
@@ -24,6 +24,6 @@ jmp .loop
 .done:
 
 ;Load the initial registers from the stack
-popa
+pop ax
 
 ret
diff --git a/SOURCE/READCH.INC b/SOURCE/READCH.INC
index 012e022..9b0680e 100644
--- a/SOURCE/READCH.INC
+++ b/SOURCE/READCH.INC
@@ -25,5 +25,4 @@ pop bx
 mov ah, bh
 pop bx
 
-.done:
 ret
diff --git a/SOURCE/READSTR.INC b/SOURCE/READSTR.INC
index 2c96c0f..16b7d42 100644
--- a/SOURCE/READSTR.INC
+++ b/SOURCE/READSTR.INC
@@ -3,7 +3,10 @@
 readstr:
 
 ;Store the initial registers in the stack
-pusha
+push ax
+push bx
+push cx
+push dx
 
 ;Store the input length in the stack
 mov ah, 0
@@ -116,7 +119,10 @@ jmp .findend
 .done:
 
 ;Load the initial registers from the stack
-popa
+pop dx
+pop cx
+pop bx
+pop ax
 
 ret
 
diff --git a/SOURCE/SYSTEM.ASM b/SOURCE/SYSTEM.ASM
index 7d4eaae..5ea6f85 100644
--- a/SOURCE/SYSTEM.ASM
+++ b/SOURCE/SYSTEM.ASM
@@ -1,4 +1,6 @@
-[ORG 0x9e00]
+CPU 8086
+ORG 0x9e00
+
 jmp start
 
 ;Calls
@@ -86,26 +88,18 @@ mov si, error
 call println
 jmp loop
 
-cpl:
-db 0x0
+cpl db 0x0
 
-welcome:
-db 0xd, 0xa, "Welcome to EttinOS!", 0xd, 0xa, 0x0
+welcome db 0xd, 0xa, "Welcome to EttinOS!", 0xd, 0xa, 0x0
 
-prompt:
-db "> ", 0x0
+prompt db "> ", 0x0
 
 cmd:
-.echo:
-db "echo", 0x0
-.hello:
-db "hello", 0x0
-.help:
-db "help", 0x0
-.keycode:
-db "keycode", 0x0
-error:
-db "Unknown command", 0x0
+.echo    db "echo", 0x0
+.hello   db "hello", 0x0
+.help    db "help", 0x0
+.keycode db "keycode", 0x0
 
-buffer:
-times 0xff db 0
+error db "Unknown command", 0x0
+
+buffer times 0xff db 0
diff --git a/make.sh b/make.sh
index ffa2d71..8ae9905 100755
--- a/make.sh
+++ b/make.sh
@@ -1,11 +1,18 @@
 #!/bin/bash
 
 cd SOURCE/
-nasm BOOT.ASM -f bin -o ../BOOT.BIN
+
+if [ "$1" == "-F1440" ]
+    then nasm BOOT.ASM -d F1440 -f bin -o ../BOOT.BIN
+    else nasm BOOT.ASM -f bin -o ../BOOT.BIN
+fi
 nasm SYSTEM.ASM -f bin -o ../SYSTEM.BIN
 
 cd ..
 rm -f EttinOS.img
-mkfs.fat -C EttinOS.img 1440
+if [ "$1" == "-F1440" ]
+    then mkfs.fat -C EttinOS.img 1440
+    else mkfs.fat -C EttinOS.img 360
+fi
 dd if=BOOT.BIN of=EttinOS.img conv=notrunc bs=512 count=1
 mcopy -i EttinOS.img SYSTEM.BIN ::