Wikipedia:Reference desk/Archives/Computing/2008 May 5

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May 5[edit]

Playing foreign DVDs on a PC[edit]

Two questions about importing US DVDs to play on a UK PC. Firstly, I've got two DVD drives in my computer. Is it possible to set one to Region 1 and the other to Region 2 (or, alternatively, would setting them to Australian make them play any Region, since Australia has banned the use of Region coding)? Secondly, will the computer play NTSC format just as easily as it does PAL? Laïka 01:37, 5 May 2008 (UTC)

Yes, you should be able to set them to different regions. No, setting to Australia wouldn't work; if what you say is so, their DVDs aren't region encoded, so any Aussie DVDs you get will work in any region, but the Australia region will not work with any DVD. (You can get drive firmware hacks that ignore region encoding, though). And yes, PAL and NTSC will be fine with any normal DVD-playing software. (talk) 01:45, 5 May 2008 (UTC)
I don't think Australia has actually banned the use of region encoding of DVD discs, but manufacturers of standalone DVD players were warned by the ACCC that making players which only played Region 4 may violate the Trade Practices Act - pretty far from a ban. If you set your PC drive to Region 4, then it would not play Region 1 DVDs (Region 4 is also used in the Pacific Rim, Mexico and South America and so would be unaffected by Australian law). Bear in mind that a lot of UK Region 2 discs are dual-encoded to work in Region 2 and Region 4 so that the distributors can save money on mastering the DVD and use the same press for the UK and Australia. And yes, in answer to your original question, you can set one to Region 1 and one to Region 2. --Canley (talk) 06:20, 5 May 2008 (UTC)
If you use VLC Media Player, you shouldn't have to worry about region codes at all. --LarryMac | Talk 13:06, 5 May 2008 (UTC)
A small word of caution though. Many modern computer DVD drives have firmware that willspontaneously change the region, but only up to five times - then it's locked into the last region it switched to. There might be some firmware hacks to get round this, but I've no idea where to find them. Astronaut (talk) 14:18, 5 May 2008 (UTC)

Name of a sorting algorithm?[edit]

I would like to know the name of a sorting algorithm. When I did some work in an office sorting papers, I used a method similar to this (although modified for a desk without space for 20-odd stacks of paper).

First, sort the items by first letter (digit, byte, whatever). Do this by making 26 (or 10 or 256 or however many) piles, one for each distinct first letter (or digit or whatever, I'm just going to say "letter" from here on). Now gather up all these piles so you have one big pile with all the items sorted alphabetically by first letter. Now you use recursion. Take all the A's from the top of the pile and put them into 26 piles according to the 2nd letter of the name. Then you take all the Aa's from the top of the pile and sort them, and then take the Aaa's and sort them, and so forth recursively. Once you're through with the A's, you sort the B's, C's, and so forth, and this also applies recursively: you finish sorting the Aa's before tackling the Ab's, etc. If at any stage the number of items is so small that it would make more sense to use e.g. bubble sort for that stage, do so. —Preceding unsigned comment added by (talk) 03:11, 5 May 2008 (UTC)

It is called a bin sort. -- kainaw 03:21, 5 May 2008 (UTC)
I'd call it MSD radix sort. « Aaron Rotenberg « Talk « 04:51, 6 May 2008 (UTC)

Computer beeps[edit]

Hi, my computer gives long beeps and through that alternating high-low beeps (and ofcourse won't do anything else). According to the beep codes, the first one should be something wrong with my RAM and the second that something is wrong with the CPU. I cleaned the CPU fan (which appeared necessary) so it might well have been overheated. Is there something I could still do myself that could possibly still fix this? Emil76 (talk) 08:46, 5 May 2008 (UTC)

Removing and re-inserting the RAM modules very often fixes RAM issues, even if they are inserted correctly (and it doesn't hurt to double-check that they are, indeed, inserted correctly). The same can work for the CPU. Is it a computer that has worked before? Otherwise it could also be that the CPU is incompatible with the motherboard, or that you need to update the BIOS. By the way, it takes time for components to overheat, if it was a fan issue I doubt you would see it at boot. -- Meni Rosenfeld (talk) 09:43, 5 May 2008 (UTC)
Thanks for the answer. The computer has worked before. It just happened one day, so it's quite unlikely that the RAM got loose or something, but I did check that (a few times). You say "the same can work for the CPU", you mean that I could get the CPU out and try to reinsert it? Emil76 (talk) 09:57, 5 May 2008 (UTC)
Yes, you should try reinserting the CPU (preferably wearing an antistatic wrist strap, or else taking some other precaution). Try clearing the CMOS memory. I assume you have two RAM modules (perhaps more) - try booting with only one module attached (the one closest to the CPU, in a mainstream contemporary motherboard). If you have compatible RAM and CPU available, try putting them. It might also be a PSU issue. If the problem persists after checking all that, your motherboard is probably dead. -- Meni Rosenfeld (talk) 10:24, 5 May 2008 (UTC)
If it was a siren beep (high-low-high-low...) then you most likely overheated. Once that happens, you run a high risk of damaging the CPU. If all your efforts of cleaning and remounting the hardware fail, look into getting a new CPU. -- kainaw 12:11, 5 May 2008 (UTC)
Make sure that your cleaning of the fan didn't short circuit or break the solder tracks on the motherboard. Make sure you didn't disturb any of the jumpers on the motherboard. You didn't remove a small piece of foil? Astronaut (talk) 14:30, 5 May 2008 (UTC)
Thanks for the answers. I'll have to do some studying first on how to remove the cpu and reinserting it or inserting a new one. Never did something like that before :) Emil76 (talk) 19:24, 7 May 2008 (UTC)
We can try to help if you tell us what kind of CPU \ motherboard you have. -- Meni Rosenfeld (talk) 19:54, 7 May 2008 (UTC)

BLAST one sequence against database and return a hit for each sequence in the database[edit]

Hi, I'd like to BLAST a small sequence that is in most, but not all of the sequences in my database. I'd like to return, at most, one hit per sequence in the database. Any idea on how to do this? (the -v and -b parameters are set to greater than the size of database. The -K parameter may influence this, but it's not necessarily what I want.) Anybody have any suggestions? THanks. --Rajah (talk) 21:50, 5 May 2008 (UTC)

Do you mean you wish to return the best match of all the sequences in the database? If all of your sequences have exactly the same subsequence to your query, then BLAST will not be able to distinguish between them. Rockpocket 22:12, 5 May 2008 (UTC)
First, I would compile BLAST as a module for my database (ie: a MySQL module). Then, I could run a query like: "select sequence from mytable where blast('AGAT',sequence) limit 1". That gets one hit from the database for the little sub-sequence if the BLAST function returns true. It would be trivial to expand this to handle multiple sub-sequences or wrap the query in a script that performs it over and over for each sub-sequence. -- kainaw 00:54, 6 May 2008 (UTC)