Category: DOS kernel
Flags: Undocumented function
INT 21 - MS-DOS 7.0+ - CONFIG$ device - SET??? CONFIGURATION INFORMATION
AX = 4403h
BX = file handle for character device "CONFIG$"
CX = number of bytes to write
DS:DX -> buffer containing ???
Return: CF clear if successful
AX = number of bytes actually written
CF set on error
AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h)
Note: IOCTL Output to CONFIG$ is only available while IO.SYS is booting
the system; once CONFIG.SYS has been processed, this call always
succeeds, ignoring any input