KVM Switch ghost

I  finally decided to buy another computer to augment my 7 year old W98 workhorse. A KVM switch seemed the best solution to the lack of room on my desk so I bought a very inexpensive KVM switches. It worked a treat --two pushes of  one key and a push of another and my keyboard and display get connected to the other machine. The mouse connections were USB and were not connected to the KVM switch.

The problem was that the display was degraded with a ghost
Ghosting can be caused by reflections in the video cables caused by incorrect matching of the impedance to the equipment at the sending or receiving ends. It could be caused by the cable itself. Whatever the cause I surmised that it would be improved if the cable was shorter than the 1.7m provided with the switch.
The switch and cables cost less than $40 and I had no qualms about cutting the old cables up The local electronics shop had the correct connectors and back shells so I made up some short leads.



A  lot of care was taken to ensure that the connections to the new plug duplicated the old ones and that there was no shorts or possibility of a short between the pins. If you are not skilled at this sort of project  having a short lead made by somebody will cost about a much as the KVM switch.

The result was perfect to my eyes as can be seen from this enlarged view. The "F" is actually about 3mm high.
















$40 was very little to pay for a KVM switch that came with and 2 x 2m cables.  I was surprised that the cable with the KVM switch did not have individually shielded coaxial cables for the RG & B signals. When compared with the cable from an old monitor you can see the difference. The old cable not only used individual shielded coaxial RG &B connections but the shielding consisted of braiding and foil. I can now see why the cheap cable performed badly.








Keeping your old computer and using a KVM switch

I spent many years supporting accounting packages of a variety of multi-user operating systems. Upgrading the operating system was always a dicey business as it invariably broke something in the software or the hardware drivers.  My Windows 98SE machine was 7 years old  and had never needed to have Windows reloaded.  A few battles had to be waged to maintain a steady gradual improvement in the machine and in the end it contained hundreds of useful and free programmes. It had been upgraded with fast disks and faster processor but age will eventually kill the mother board so I decided to buy a new computer with Vista. XP was said to be more developed and less hassle but I took the opportunity to bypass it.

You may like to consider keeping your old machine even if there is not another user for it in the household. The set up I now have gives me a powerful work station. With the press of a couple of keys I can instantly swap the keyboard and display from one machine to the other and the Netcom NB5 modem router enabled me to set up my two machines on a LAN  (Ethernet  on one and USB on the other machine). I have internet connection to both machines and they share the printer on the W98 machine. The printer by the way is a Canon BJC-2100SP. A real slow workhorse that seems indestructible and economical to refill using bulk ink. I use a black only cartridge that is easy to fill. There is something to be said for a lower dot density—the nozzles are bigger—more robust and not prone to clogging. I have printed thousands of pages albeit slowly. I prefer to read from paper and things like the modem manual of 200 pages was printed out as a matter of course. 

The latest piece in the puzzle was getting  printer sharing to work. Google is a wonderful resource and revealed that on vista you add a new printer that matches the one you want to share and do not give it a real port but in the port drop down box select the printer on the networked machine that you had set up to share previously. I was very surprised to find that Vista had a  ready to go driver for the old Canon.
As I gradually bring programmers over from W98 to Vista and run them directly or in a virtual W98 machine using the free Microsoft Virtual PC I am finding that the old computer is being turned on less often. It was a great discovery that the printer could be physically connected to both machines using the parallel port for W98 and USB for Vista and would print happily from either connection. I will look for this dual input feature on any new printer—no network or switches required.



End.