PC Card (PCMCIA)
Windows NT 4.0 supports laptops and other systems with PC Card (a.k.a. PCMCIA) devices via the Control Panel PC Card (PCMCIA) applet (shown in Figure 5.36).
Double-clicking this icon displays a window with a list of all currently installed PC Card/PCMCIA devices in your system. You can change several properties for a PC Card/PCMCIA device, including the device’s hardware resource settings and driver. To change the properties of an installed PC Card/PCMCIA device, select the device’s name and click the Properties button. The device’s properties window appears. This window has three tabbed sections: CardInfo, Resources, and Driver.
The CardInfo tab displays a summary of information about the device, such as the device name, driver used, and status (whether or not the device is working properly).
The Resources tab (shown in Figure 5.37) lets you change the resources used by the device, such as hardware interrupts, I/O base addresses, and DMA channels. To change these settings, first turn off the Use Automatic Settings check box. To change a particular resource setting, highlight the setting and choose Change Settings. If this option is grayed out (unavailable), this device does not support manual configuration and is always automatically configured.
The Drivers tab (shown in Figure 5.38) lets you add, remove, or configure the driver used by Windows NT 4.0 for the PC Card/PCMCIA device. To perform any of these actions, choose the appropriate button. When you add a driver, Windows NT will display a list of drivers to choose from, or you may use the Have Disk option to install a vendor-supplied driver from a disk.
Tip: Whenever you install a new PC Card/PCMCIA device on your system, be sure to run the PC Card (PCMCIA) applet immediately. When you run this applet, Windows NT 4.0 will offer to automatically load a driver (or you may load one manually via the Have Disk option) to support the device. Until this is done, Windows NT will not be able to support the device. A red X appearing next to the device indicates that Windows NT doesn’t support the device or that no driver is available. If this is the case, you should check with the device’s manufacturer about support. Before purchasing a PC Card/PCMCIA device, you should make sure that it is on the Windows NT Hardware Compatibility List (HCL).
Caution: Windows NT 4.0 does not support the “hot swapping” of PC Card/PCMCIA devices (i.e., changing the device while the system in turned on). Windows NT loads devices for all hardware at startup and requires that any PC Card/PCMCIA device that will be used during a session be installed when the system is started. Changing PC Card devices while the system is on causes unpredictable results; therefore, always turn off your system before inserting PC Card devices.
Ports
The Ports applet lets you configure your serial communications (or COM) ports in Windows NT. Windows 3.x and Windows for Workgroups users may notice that this applet is virtually identical to the Ports applet of the Control Panel utility found in those versions of Windows. Double-clicking the Ports applet icon brings up the Ports applet main window (shown in Figure 5.39).
This window displays all communications ports available for configuration in Windows NT 4.0. The list of available communications ports was created when Windows NT 4.0 was first installed on your system.
Special Note: Don’t be alarmed if one of your ports is missing from this list — it is probably the port to which your pointing device (e.g., mouse or trackball) is connected. Windows NT intentionally removes this port from the Ports dialog box and instead configures that serial port as a system device called PointerPort0. Not having the port listed prevents the port settings for the device from being incorrectly or inadvertently modified, which could potentially cause the pointing device to stop functioning properly.
If communications ports are added to the system later on, you should add those ports manually via the Add button, because Windows NT 4.0 will not automatically detect and configure them. When adding a port, you’ll be asked to input several key pieces of information about the new port, including the COM Port number, Interrupt Request Line (a.k.a. the IRQ or hardware interrupt), Base I/O Port Address, and whether or not the UART (Universal Asynchronous Receiver/Transmitter) chip driving the port contains a First-In, First-Out (FIFO) buffer.
Special Note: An example of a FIFO-capable chip is the 16550AF UART chip, which contains a 16-byte buffer. The FIFO buffer lets the chip support higher transmission rates and reduces the possibility of losing data by buffering the data being sent or received. However, ports using older UART chips such as the 8250 or 16450 do not contain a FIFO buffer.
Table 5.3. lists typical communications port numbers and their standard hardware resource assignments.
Caution: In general, you should not configure multiple COM ports to use the same IRQ in Windows NT. Although it is possible in some scenarios for devices that aren’t used simultaneously to share an IRQ, it will more often than not cause problems for you. The problems often occur when Windows NT loads drivers for devices attached to these ports (usually at startup) that begin using the interrupts immediately. If two such devices attempt to access the same IRQ simultaneously, one or both of the attached devices may fail to work properly. In this situation, the Event Viewer application will log errors to inform you of the problem.
To delete a port, simply highlight the port and choose the Delete button. To configure a port’s settings, highlight the port and choose the Settings button. This will display the Port Settings dialog box (shown in Figure 5.40).
This dialog box lets you configure various settings for the COM port, including baud rate, data bits, stop bits, parity, and flow control. These terms and their meanings are described in Table 5.4.
For each of these items, check the documentation that comes with the device you will be attaching to the port for the correct settings. If no mention of COM port settings is made, then leave the settings at their default values. If this does not work, either experiment with different settings or contact the device’s manufacturer for help with configuring the port.
Tip: When the COM port being configured is part of an internal modem rated at 14.4 bps or faster, you should always set the baud rate higher than the speed of the modem. The baud rate controls the DTE (Data Terminal Emulation) rate of the port, which is the speed at which information is sent from the computer’s CPU to the communications port. Setting this rate higher ensures that you will get the maximum possible throughput from your modem. For the exact baud rate setting you should use for the modem, see the modem’s documentation. For external modems, the maximum baud rate for the port may be limited by the capabilities of the UART chip driving the port. See your computer’s documentation for information concerning the capabilities and correct baud rate settings for your system’s external communications ports.
The Advanced button lets you configure low-level information about the COM port. This is the same information you need to provide when you use the Add button to add a new port, including the COM port number, Base I/O Port Address, Interrupt Request Line (IRQ), and whether or not a FIFO buffer is present on the port.
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