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Incompatibilities With Non Windows OSs - 8/22/00

Due to Windows ubiquity, hardware products are typically developed for Windows before other systems. Taken as a group, its hard to think of any other software that is installed on nearly as many computers. Though there are certainly differences between Windows 95, 98, NT and 2000, they also have much in common and unless a product needs special features in one of the OSs, manufacturers try to make products that will work with the entire Windows family. Anyone whose worked with other OSs knows that you need to be careful about what hardware you use in your computer because newer and more exotic hardware often does not have necessary software drivers for other OSs.

One might think that the OS should not have any impact on certain external hardware such as keyboard, video and mouse sharing boxes (KVMs). After all a KVM sits between the peripherals it controls and the computers to which its connected and the OS is on the computer. In practice however, the OS seems to affect KVMs, perhaps not like internal boards that may not work at all, but enough so that the differences can't be completely ignored.

I use a Belkin OmniView Pro 8-Port model KVM. Overall I'm pretty satisfied with it and it's certainly a cost effective sharing solution. I have however found some distinct differences in the way it works with different OSs. This KVM has front panel buttons to switch computers but the keyboard hot keys are much faster; they are [Scroll Lock][Scroll Lock][0-9][1-8]. The two Scroll Lock keys need to be pressed in some time period less than a second. When they are the KVM beeps. Then you press a digit to select which unit or bank to activate; multiple Belkin KVMs can be stacked and even if you only have one, you still need to press zero to select it. The second digit selects the specific port or computer.

When the Belkin was new, I repeatedly locked up the keyboard on both the BSD and Linux systems. It's supposed to be two Scroll Lock presses close together but for some reason the first or sometimes even the second doesn't register with the KVM. What I was doing was pressing Scroll Lock twice very quickly and when the KVM didn't beep, doing this again. It seems that if I press Scroll Lock a third time, especially on the Linux system, there is a good chance the keyboard will lock. To keep from locking the keyboard I have to press Scroll Lock methodically until I hear a beep then press zero. Sometimes the beep comes after the second, sometimes the third or sometimes even the fourth key press.

Because the only way that I've found to clear the locked keyboard once it occurs, is to reboot the system, I've never experimented systematically to determine just what sequences cause the lockup. I have found how to largely avoid them. I know its the keyboard and not the system because all the network services including telnet logins are still working and its via telnet that I reboot the systems. I've sometimes waited days when I didn't need the console and the locked keyboard condition has never been cleared without a reboot on the Unix like systems.

On the NT systems, even though its not always the second Scroll Lock press that triggers the beep, I've only ever locked up the server once that I recall and never the workstation. (On the other hand, though not frequent, both NT systems have seen blue screens of death, spontaneous reboots and hard system crashes with no error message or warning of any kind. All the Unix like systems are much more stable. Ironically, it's the server which has much less software installed that's had more unexplainable crashes; the workstation has generally been quite stable except when installing or upgrading software.)

Keyboard lockups are not the only KVM differences. On the Linux system, on the console, I frequently encounter a situation where keyboard input won't appear until the scroll lock key is pressed once, then several characters including new lines appear at once. This is definitely a KVM issue as I've never seen anything like this in a telnet session.

Perhaps the most frustrating condition is on the Linux system. Normally no monitor output will appear when the Linux computer is not the one actively selected on the KVM. I have a script that runs on each web server that periodically pings the other servers and my ISP's router at the far end of the DSL line. If after multiple attempts spread over a time interval, contact cannot be made the script sounds the PC speaker periodically until contact is resumed. I haven't been able to get the Unix like systems to do this from background jobs so these scripts run in console sessions. Nothing I've tried will make the Linux script sound the alarm reliably when the Linux box is not selected in the KVM.

In other environments pager, email or GUI pop-up messages might be better alarm methods. In my environment, an audible alarm via the PC speaker is definitely the most likely to get my attention the soonest. As the Linux machine is the system to which and traffic are directed, it's important that I know if it loses it's network connection as soon as possible. It's annoying that the only way I've found to set up what I regard as a reliable alarm is via an elaborate workaround. Instead of sending output to the console, it goes to a file and the file is checked from a remote Windows system that will beep regardless of which system is active on the KVM.

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