Two computers in one: two users each with their own accounts, monitor, and keyboard?
in [Debian]
|
Prev: slow workspace switching ATI Radeon 3850 fglrx/non-free RandR
Next: Two computers in one: two users each with their own accounts, monitor, and keyboard?
From: Stan Hoeppner on 12 Jan 2010 09:40 Albretch Mueller put forth on 1/12/2010 4:00 AM: > The only extra cost here would be the special video cards for each > seat but even they are commercial nowadays and making multi-seat work > would be our job right? You're still missing the overall picture here. In your living room or basement, or in a library or lab with a 30 foot long desk, this concept may work, somewhat. In the real world, especially in multi room environments such as offices or a whole home installation, you end up spending more on in wall cabling, baluns, wall plates, and other devices than if you put a complete PC in each room. If you have to run XGA/SXGA/UGA signals over 50 feet the only effective way to do so is with baluns. Smae goes for USB. A cheap VGA + KVM balun kit runs about $130.50 USD: http://www.rackmount-devices.com/019-4068.html The cheapest USB balun I've found is $39.99 USD: http://www.mcmelectronics.com/product/83-11534&CAWELAID=293709399 Now to get sound to each seat, and given that your mobo's PCI slots have all been filled with VGA cards, your only option to get sound to each seat is with a USB sound device for $12.99 USD: http://www.newegg.com/Product/Product.aspx?Item=N82E16829128002&cm_re=USB_sound_card-_-29-128-002-_-Product Oops, that USB sound plug just took the only USB port at each seat, so we'll have to get a *powered* USB hub for each seat (because the voltage drop over distance is too great to run a hub remotely) for $7.99 USD: http://www.newegg.com/Product/Product.aspx?Item=N82E16817801001 Don't forget, because we're having to use USB baluns we're limited to USB 1.1 speeds of 12MB/s. Ok, so we've covered remote VGA, KB, mouse, sound, and available USB 1.1 ports for a total of $191 USD per seat. This doesn't include a video card for each seat in the host. Cheapest I could find on Newegg is this nVidia GeForce MX400 PCI card for $32.99 USD: http://www.newegg.com/Product/Product.aspx?Item=N82E16814139150 Our sum total is $130.50 + $39.99 + $12.99 + $7.99 + $32.99 = $224.46 USD. This doesn't include the additional runs of in wall CAT5 to support USB (two runs total). One run is "free" compared to a PC at every desk as that run is required for either solution. So, lets see what we can find for around $224.46 for a PC at every desk: $229.99 USD - Atom CPU, Intel GMA 950 GPU, 1GB RAM, 160GB disk, GigE and wirelees LAN, Red Flag Linux preinstalled http://www.newegg.com/Product/Product.aspx?Item=N82E16883220028 $299.99 USD - Celeron 420(1.6GHz) CPU, NVIDIA GeForce 7050 GPU, 3GB RAM, 320GB disk, 16X DVD�R/RW SuperMulti Drive, 10/100 wired, Windows 7 Home Premium 64-bit http://www.newegg.com/Product/Product.aspx?Item=N82E16883114077 AFAIK, no company is selling wireless full KVM+USB+sound boxes, making the above mentioned $229 Asus EEPC desktop far more price, installation, and maintenance attractive than a multi-seat single PC with expensive cable connectivity, maintenance, and video quality issues. You can't beat the marketplace, ever. You can only adapt what it offers to best meet your needs. From a total ROI standpoint, a cheap PC at every desk offers the best ROI. What happens when you blow up your X.org config after and upgrade? Or anything else breaks after an upgrade? It affects all seats. With individual PCs, the first one breaks and you are alerted, so everyone else keeps working while you find a fix. There are hundreds more scenarios but I don't have the time. I've wasted enough on this already. The point being, the industry and corporate worlds have already done all of the ROI, and concluded exactly the argument I'm making here. For each reason to do multi-user computing on one host there are 10 reasons against it, cost and otherwise. This is why the industry moved away from the model long ago, and buried it. If you'd like to resurrect it in your basement that's fine, but it will never take hold again, anywhere but in "the lab", at least in my remaining time on earth, which I hope to be at least another 40 years. ;) -- Stan -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org
From: Stan Hoeppner on 12 Jan 2010 14:30 Albretch Mueller put forth on 1/12/2010 12:06 PM: > In a friendly and technically honest way, what the f#ck are you > taking about? I would like to understand you because I am not > primarily a hardware guy. Why would you need "CAT5 to support USB"? From: http://www.usb.org/developers/usbfaq/#cab1 The USB cable length limit is 5 meters, or 16.4 ft. To go 100 ft with USB requires a USB balun. Read about baluns: http://en.wikipedia.org/wiki/Balun Cables and Long-Haul Solutions 1. Why are there cable length limits, and what are they? A: The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent. Since USB uses source termination and voltage-mode drivers, this has to be the case, otherwise reflections can pile up and blow the driver. This does not mean the line voltage has fully settled by the end of the bit; with worst-case undertermination. However, there's been enough damping by the end of the bit that the reflection amplitude has been reduced to manageable levels. The low speed cable length was limited to 18ns to keep transmission line effects from impacting low speed signals. From: http://en.wikipedia.org/wiki/Universal_Serial_Bus USB 1.1 maximum cable length is 3 metres (9.8 ft) and USB 2.0 maximum cable length is 5 metres (16 ft).[27] Maximum permitted hubs connected in series is 5. Although a single cable is limited to 5 metres, the USB 2.0 specification permits up to five USB hubs in a long chain of cables and hubs. This allows for a maximum distance of 30 metres (98 ft) between host and device, using six cables 5 metres (16 ft) long and five hubs. In actual use, since some USB devices have built-in cables for connecting to the hub, the maximum achievable distance is 25 metres (82 ft) + the length of the device's cable. For longer lengths, USB extenders that use CAT5 cable can increase the distance between USB devices up to 50 metres (160 ft). I'll let you research the video signal quality problems of long VGA DB15 or DVI cable runs on your own. I will say now that the electrical signal drive circuitry on almost all VGA cards is not designed to drive into a load over 50+ ft cables. Sure, ultra expensive cables can maybe get you to 100 ft without significant image quality loss (but again the cables cost as much as a PC), but to go beyond 100 ft you really need a balun, especially if you're trying to run high resolutions and refresh rates. Apparently you've only looked at my email display name up to this point, not the domain I'm sending from. ;) You've not actually tried to do what you talk about here or you'd have already run into the 100 problems you'll have making this work, just on the hardware side of it alone. I've been there and done that WRT to console extension. It's a niche market and the products that actually make it work worth a damn are *not* cheap. On some installations I've done, the hardware, cabling, and labor cost was 10x what a PC and CAT5 would have cost, but the customer had to have it that way for security reasons. I'm telling you from experience, doing remote consoles *correctly* is expensive, and you're talking about far more capability than we were doing with adding USB and sound capability. -- Stan -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org
From: Albretch Mueller on 12 Jan 2010 15:30
> The USB cable length limit is 5 meters, or 16.4 ft. To go 100 ft with USB requires a USB balun. Read about baluns: http://en.wikipedia.org/wiki/Balun ~ OK, I got your point accross better now. The thing is that I wasn't really thinking this way about implementing it from a hardware point of view ~ I had in mind using those shielded monitor cables to transfer media in and out of the multiseat box and monitors do that right now, so it becomes less of an issue. That may need other type of hardware/protocols but it is feasible ~ > 1. Why are there cable length limits, and what are they? > http://en.wikipedia.org/wiki/Universal_Serial_Bus ~ Well yes and I never claimed that USB would be the smartest way to go for larger lengths. In fact multiplexing the signal on the same fat video cable would be best and it is doable. ~ > I'll let you research the video signal quality problems of long VGA DB15 or DVI cable runs on your own. ~ Thank you I will look into it when I get a bit more reading/searching/thinking time ~ > I will say now that the electrical signal drive circuitry on almost all VGA cards is not designed to drive into a load over 50+ ft cables. Sure, ultra expensive cables can maybe get you to 100 ft without significant image quality loss (but again the cables cost as much as a PC), but to go beyond 100 ft you really need a balun, especially if you're trying to run high resolutions and refresh rates. ~ I think 100 ft (30+ meters) is already a pretty long distance ~ > Apparently you've only looked at my email display name up to this point, not the domain I'm sending from. ;) ~ Well, I won't and I hope you don't belong to the inquisition or its modern forms ;-) This interchange was good because even if we got emotional/hyper we kept it to the point/the issue at hand. We just think differently and I am more hopeful than you perhaps because I am less of a hardware person ;-) ~ lbrtchx -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org |