Added COMMAND, SYS and HEX2BIN

Added the reconstructed source code of COMMAND.COM, SYS.COM and HEX2BIN.COM.

SYS.ASM

@@ -0,0 +1,58 @@
+FCB	EQU	5CH
+
+	ORG	100H
+	JMP	START
+SECS:
+	DW	52	;Patch for different configs
+
+START:
+	MOV	AL,[FCB]
+	OR	AL,AL
+	JZ	BADDRV
+	DEC	AL
+	JZ	BADDRV
+	MOV	[FCB],AL
+	MOV	CX,[SECS]
+	MOV	DX,0
+	MOV	BX,END
+	MOV	AL,0
+	INT	37
+	JC	RDERR
+	POPF
+	MOV	CX,[SECS]
+	MOV	DX,0
+	MOV	BX,END
+	MOV	AL,[FCB]
+	MOV	AH,1
+	INT	38
+	JC	WRERR
+	MOV	DX,TRANSOK
+	JP	QUIT
+
+RDERR:
+	MOV	DX,RDERMSG
+
+QUIT:
+	MOV	AH,9
+	INT	33
+	INT	32
+
+WRERR:
+	MOV	DX,WRERMSG
+	JP	QUIT
+
+BADDRV:
+	MOV	DX,BADDRVMSG
+	JP	QUIT
+
+TRANSOK:
+	DB	"System transfered$"
+RDERMSG:
+	DB	"Disk read error$"
+WRERMSG:
+	DB	"Disk write error$"
+BADDRVMSG:
+	DB	"Bad drive specification"
+
+END:
+