| IV.2 Trouble under MS-DOS These are problems that are specific to DOS-based host platforms, including Windows 3.1x. Most of it also applies to Windows 9x systems. When initializing the serial port, the DOS MODE utility aborts with an error message like: "function not supported on this computer", or "invalid parameter", or something like that. On most PCs, the BIOS doesn't support baudrates greater than 9600 Baud. MODE itself doesn't support baudrates greater than 19200 Baud. However, most terminal emulation programs can operate at baudrates of up to 115200 Baud. The RESET51 program aborts with "port not found". The PC-BIOS didn't recognize the printer or serial port specified. Try another port or check your PC hardware. The RESET51 program aborts with "hardware failure". The PC-BIOS has recognized the specified port, but the data latch (printer port) or modem control register (serial port) doesn't work. Try another port, or check the defective port. The PC hangs when data are sent over the serial interface in batch mode. The RS-232 cable may be plugged into the wrong COM-port. First of all, try the other ports. There may also something be wrong with the modem control signals. (See chapter II.3 Tailoring the Cables.) It works in interactive mode, but the PC hangs, if data are sent in batch mode. There is something wrong with the modem control lines! Employ the BOOT-51 User's Manual and check the RS-232 cable at the PC side connector. When invoked, the MS-DOS MODE command hangs, or fails to change the previous baudrate, although it terminates without error. Remove all networking and communication drivers and TSR programs from your CONFIG.SYS and AUTOEXEC.BAT files, reboot, and try it again. There is plenty of quick'n dirty software, doing something strange with the BIOS interrupts!