Windows ports are 'Plug and Pray'

Windows ports are 'Plug and Pray'

Q We have a Compaq Presario with

problems with communications ports. Windows 95's Device Manager shows three ports: COM1 through COM3. However, when we check the properties of the internal Compaq modem, it says it's assigned to COM4. Why doesn't Windows 95 show this port? The HyperTerminal accessory program can dial out on this modem, but WinFax 3.0 cannot. We tried to reconfigure the modem to use a different port, but then the Device Manager started to say that it was on COM5. Is this possible? What should we try next?

A I get several queries a month describing variations on this problem. Windows 95's "Plug and Pray" support often seems to behave irrationally: Device Manager sometimes shows a modem without an associated serial port, modems are not always available in DOS sessions, and sometimes one program can see a device when another can't. Microsoft's Knowledge Base ( addresses some specific situations but doesn't give a foolproof fix. Anda technical-support representative would not acknowledge the problems when I called. In myexperience, most serial-port and modem problems are due to one of two conditions that Windows 95 does not handle well. The first is a "skipped" port number (for example, you may have a COM1, a COM3, and a COM4, but COM2 is either absent or used for a mouse). Once it skips a number, Windows may not use it later if you install a new device. Instead, it will give new hardware a higher port number: COM5, COM6, and so on. Many applications (especially DOS programs) can't deal with these designations. The second problem is "phantom" hardware - a device that has been physically removed from the system but still seems to have resources reserved for it. This most often occurs with PC Cards.

My brute-force solution is as follows: before changing any serial or modem hardware on a Windows 95 computer, I open the Modems applet on the Control Panel, select each device on the list (including ones I want to keep), and click "Remove".

Next, I go to the System applet's Device Manager, select each serial port and serial device (including infrared ports), and again click "Remove". I also insert each PC Card I've used since the last reconfiguration, wait for it to be recognised, and use one or both of the "Remove" buttons on it.

I then shut down, turn off the power, and swap hardware.

Fully functional

Next, I turn the system on and let it rediscover each device afresh. If I want a particular PC Card to get a low port number such as COM1 or COM2, I insert that card during this boot so that it's first in line. I also make sure to have my Windows 95 and driver disks ready, because Windows may not proceed without them.

Each internal or PC Card modem should be detected as a communications port, if not as a modem. If a modem is seen as a serial port only or goes unrecognised or the serial mouse locks up, I let the machine stabilise and try another cold boot.

If the system doesn't recognise a modem the second time around, I use the Modems applet to install it. As each modem is installed, I set its communications port in the Modems applet. If I plan to use additional PC Cards, I insert them one at a time.

This usually requires several reboots.

This procedure is anything but Plug and Play. But it's often the only way to make your machine fully functional when changing serial devices on a Windows 95 computer.

When you install serial devices on a Win95 machine, there are two other potential problems you should be aware of. First, Win95 often fails to report interrupt conflicts between serial devices on IRQs 3 and 4.

If you don't eliminate conflicts by hand, your system will behave erratically, and your serial mouse may freeze. Also, some device drivers create entries in the Windows Registry. No uninstaller reliably detects these, so if you can't get Windows to number ports the way you want, remove the entries by hand.

Painlessly restart Net file


Q When I use my Windows 95 machine

to download large files from the Internet, I'm sometimes disconnected in the middle of the transfer, and I have to start the download again. When I use the ZModem protocol to download files from BBSes, I can resume a file transfer in the middle if I'm cut off. Is the same capability available on the Internet?

AYes, FTP has a built-in command called

reget that allows you to restart a transfer in the middle. Most FTP servers, including the ones in FreeBSD and Linux (the most popular OSs for Web servers), will respond properly to it. Likewise, the FTP clients that come with most Unix systems can issue this command. However, the text-based FTP client that comes with Microsoft Windows 95 does not know how to. Neither, alas, do the stripped-down FTP clients built into most Web browsers. The solution: get an FTP client that can handle the reget command. Quite a few free and shareware FTP clients support it, and commercial implementations almost always do.

Because the more powerful FTP utility won't be integrated into your Web browser, and because browsers generally throw away incomplete downloads, you'll need to start each of your big file transfers in the FTP client. To do this, position the mouse pointer over the link to the file in your browser. Read the URL from the status box at thebottom of the screen. (It'll begin with ftp:// if it's an FTP link.) Break it into a host name and a file name, and enter both parts into the FTP client. I hope that browsers will gain support for the reget command in the future, and this extra effort will become unnecessary.

Get on the Net by sharing modems, routersQ Many small businesses or remote offices with small networks would like to be able to share a single modem connection to the Internet among several computers. The only solution I have found is a small router. Is there a less expensive solution?

A In my consulting practice, tying multiple workstations to a single Point to Point Protocol connection is one of the most common problems I solve for clients. There are many ways to do this, but they all have a common thread: one of your users' PCs needs to also act as a router. (Note that I didn't say "a router" but rather a PC that must "act as a router". For low-bandwidth applications, it's perfectly OK to set up one computer as a router for the rest.) The router receives packets from the Internet, routes them to the right workstation, and sends outgoing packets over the single modem to the outside world.

The logistics of setting up the connection will depend on the nature of your relationship with your ISP. If you have a cheap, individual account with an ISP you'll get a single IP address while you're connected, and that address will change every time you connect. This has some drawbacks. First and foremost, you won't be able to set up any of your machines as a server (for instance, a Web or mail server) for use on the Internet. (You must have a fixed IP address to do that.) Also, you'll need to share your one temporary IP address among several computers. The original design of the TCP/IP protocol stack did not contemplate the notion that multiple computers would ever share an address, so the machine with the modem must perform "IP masquerading" to let the others share its link to the Internet.

In IP masquerading, one machine acts as a proxy for the others when they access the Internet. Every time one of the clients attempts to establish a communications session with another machine across the Internet, it connects instead to the proxy. Using its own IP address, the proxy establishes the session on behalf of the client.

Most firewall routers can perform IP masquerading. Both FreeBSD and Linux have free routing and firewall software; other programs, such as Wingate ( are available for platforms that include Windows and Windows NT. A marvellous free program called Slirp ( lets a Unix machine on the Internet perform IP masquerading on behalf of clients that dial in via a modem. Finally, commercial firewall software is available from dozens of companies.

If you're using an Internet service that relies upon proprietary software, you may be restricted in your choice of platforms. The main disadvantage of IP masquerading is that the clients might not be able to use certain Internet applications, such as some Internet telephony programs. Why? Because some of these programs have been written with the shortsighted assumption that each party has a unique IP address.

What if you want to set a full-time, shared modem connection to the Internet - one that allows you to have a domain name and set up a Web server? Or what if you want an IP address for each of your workstations, so that masquerading isn't necessary? In these cases, give a local ISP a call. Such services are more expensive than a "generic" Internet account, because your ISP will need to dedicate a telephone line and at least one IP address for your use. But the ISP can also set up a domain name. The service provider can also help you to configure one of your machines to work as the router on your LAN.

If you use a computer as a router, it should still be capable of functioning as a workstation or local server - so long as it is fast enough and the OS has good multitasking. Unix machines are especially suitable for this task because software is included.

Go with large format displays

Q I just upgraded several workstations

to new, high-resolution video cards that display 1280 by 1024 or 1600 by 1200 pixels. But the systems' monitors just can't handle the challenge of the new cards. All the pixels appear, but small text is blurry and hard to read. I went to my local electronics store and noticed that even the new monitors selling with the latest consumer systems (such as Compaq and Sony) had the same problem at 1280 by 1024 [pixels]. Where can I get monitors that match the quality of our new graphics cards?

A You've discovered an embarrassing truth about the progress of computer tech-nology. Although some performance factors (such as memory density, hard disk capacity, and CPU speed) have increased tenfold in the past several years, others (such as CRT resolution) have virtually stood still. Costs have dropped, but most monitors that are sold today have a dot pitch no finer than what you could get from a decent model in 1991.

Dot pitch is defined as the shortest distance between two phosphor dots of the same colour on your CRT's screen. It's smaller than the distance between pixels; a pixel must span several phosphor dots to be visible.

Trinitron monitors, which have stripes rather than dots, don't have a dot pitch; they have an aperture grille pitch (the distance between the stripes). The two numbers don't mean quite the same thing in terms of picture clarity. With alittle geometry, you can show that a dot pitch of 0.28 millimetre is roughly equal to an aperture grille pitch of 0.25 millimetre.

A small dot pitch (or aperture grille pitch) is vital to picture clarity on a computer monitor. Typical consumer monitors have a dot pitch of 0.26 to 0.28 millimetre.

What to do, then, if you want a clear high-resolution display? Until monitor vendors catch up with the rest of the computer world (or we all switch over to LCDs or plasma displays, which are making great strides each year), your best shopping strategy is to buy monitors that are larger than the standard equipment.

This will allow each pixel to cover more phosphor dots, increasing clarity. So-called 17in monitors (which picture area really measures about 15 or 16 inches diagonally) are the practical minimum for 1280 by 1024 pixels; 21inor larger monitors are necessary for any higher resolution.

ZIP zap zop

Reader Mohit Goyal has alerted me to a problem with shifting Zip-drive letters on Windows 95 systems. According to Goyal, when the system is booted with a disk in the Zip drive, it is assigned a drive letter after that of the last hard disk; however, if there's no disk in the drive, it gets a letter later in the alphabet. This does not occur in OS/2 Warp or other OSs, and it is probably related to driver implementation. To work around the problem, "lock down" the drive letter using Windows 95's Device Manager or just remember to insert the Zip cartridge after the system boots.

Extra DOS memory

Several readers have written to say that they've boosted DOS memory under Windows 95 by loading Microsoft's HIMEM.SYS and EMM386.EXE from the CONFIG.SYS file. These memory-management programs allow DOS drivers to be loaded into upper memory. They won't break the 640K memory barrier, but they may get you as much as 620K for DOS programs.

Ring up the dollars

Q I've heard of an Internet fraud in which a Web causes your modem to hang up and then dial a very expensive international toll call. What's happening? How can we guard against it?

A Apparently this nasty prank was

executed via a rogue ActiveX

control. An ActiveX control, unlike a Java applet, is a full-fledged Windows application that can easily take complete control of your machine. To avoid the problem, don't enable ActiveX controls, or simply use a browser that doesn't support this dangerous feature. You might still get hoodwinked by a network scam, but you'll be far less likely to start a Trojan horse program without knowing it.

Follow Us

Join the newsletter!


Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.


Show Comments