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Thinking About VNC—Day 60© Copyright Darrell Anderson. I spent several hours surfing and researching VNC—Virtual Network Computing. The concept is another example of how people can create useful products. Because of my frustrations and untrustfulness of WINE, I want to investigate using VNC to control my NT4 box from my Slackware box. That option would allow me to maintain the integrity of my Word writing environment while I continue migrating. Although I can use Word under WINE (I am doing so right now), I am unable to tweak my VBA environment because I am unable to run more than two Windows programs concurrently. I am not going to spend time trying to figure out why. My research revealed a mixed bag of opinions. My primary concern is speed and latency. Consider some basic numbers. Like my Slackware environment, I run my NT4 screen at 1280 x 1024 pixels. This is the native resolution of my LCD monitor. Multiply those two numbers to derive the total number of pixels. Then multiply by 15 (bits per plane) because that is the screen resolution I run with my old first generation 3D video card. That math exercise reveals that each screen display requires 19,660,800 bits of storage, or, to simplify calculations, approximately 20 megabits. For the moment, ignore the real world and real overhead. Assume a 10 Mbit/sec network card. Each screen display therefore requires approximately 2 seconds to transmit through the network connection. That would mean the display would lag about 2 seconds behind my typing—not useful in a word processing environment. However, I can do better because 100 Mbps network cards are common. Thus, reduce that transmission time by 10 to 0.2 seconds. In a writing environment, that kind of latency is doable but probably still disruptive. I can do better. For many years I ran NT4 at 1024 x 768. That changes the numbers. Now I need to push 1024 x 768 x 15. That equals 11,796,480 bits of information, or approximately 12 Mbits. That 100 Mbps card now moves the data in a theoretical .12 seconds. Better. More doable. Real world overhead increases these simple results. Overhead is a real-world factor that must be included. However, VNC includes compression algorithms. So at this point I don’t know the actual response I’ll see if I run Word from my NT4 box through VNC. Yes, I could run Word at 800 x 600, but I have grown so accustomed to 1024 x 768 and now 1280 x 1024 that I wonder if my mind could adjust. Additionally, the tool bars in my Word layout are based upon 1024 x 768. Reducing to 800 x 600 probably will disrupt that layout. Nonetheless, if latency proves awful, then I probably will need to consider that option. I downloaded the TightVNC packages for both Windows and Slackware. However, I later remembered that KDE already supports VNC. Therefore I do not need to install VNC in my Slackware box. All I need do is configure my NT4 VNC server and then use KDE to point to that box and connect. I need to obtain a second network card. My NT4 box already contains a 3COM 3C509 10/100 card and the Linux kernel recognizes the card with no issues. I have some CAT-5 crossover cables lying around. All I need is another 100 Mbps card. I have not yet reinstalled Slackware to my second box since my partitioning fiasco a while back. Reinstalling Slackware should require a leisurely hour or so. However, to support this VNC experiment I want to increase the available RAM in that box. Currently I have 256 MB in each box. My NT4 box is physically limited to a maximum of 256 MB, but the second box can expand to 768 MB. I want to use the virtual desktop concept to run my NT4 VNC session in a second virtual display. Thus, I’m sure additional memory will help VNC sessions. I can swap memory sticks to increase the RAM in my second box. I can change the NT4 box to 196 MB of RAM to increase the second box to 320 MB. Or, using some older RAM sticks, I could change the NT4 box to 128 MB and increase the second box to 384 MB. I actually ran NT4 with only 64 MB waaaaaay back when I first purchased the box seven years ago. 128 MB is more than enough if I use NT4 only as a glorified word processor. I ran a recent test opening two books, a manual, and some essays. I used 54 MB of RAM. VNC is CPU intensive but I don’t know if the RAM reduction will play a hurtful role. That 1024 x 768 x 15 screen—approximately 12 Mbits, equals approximately 1.5 MB. Running only Word is not RAM intensive so I would think 128 MB is sufficient. If not then I probably need to barter or buy some new RAM sticks. All of this is speculation right now. However, many people use VNC. If speed and latency was that bad then I think I would have read more about that. I haven’t, so I remain cautiously optimistic about this idea. Still, I hope the idea works well. For the first time in years I had a file system table problem. Of course, this was with my new FAT32 partitions, not my dependable NT4 partitions. The error was minor and Scandisk repaired the problem. In all the years I have been using the NT4 file system, I never had a problem except when I knowingly and purposely was mucking around—and that was many years ago when I was first learning my way around NT. I run chkdsk routinely and never have problems. Never. Now, within a week after converting my data partition to FAT32, I experience an error. Was the error caused by my FAT32 driver from within NT4, through the Linux kernel, or through WINE? I don’t know. This event unsettles me. Finis. |
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