Tag: Computer

arithmetic – Computer Architecture: How does the parallel prefix adder speed up carry generation?

I am confused by how the parallel prefix adder (the one described in this presentation: https://users.encs.concordia.ca/~asim/COEN_6501/Lecture_Notes/Parallel%20prefix%20adders%20presentation.pdf) speeds up carry generation (specifically the Ladner-Fischner adder architecture). I understand how carry generation in a non-parallel CLA (carry-look ahead) adder works—carry bits are computed using just the initial carry bit ($C_0$) and propagators and generators:

$C_{i} = G_{i – 1} + P_{i – 1}G_{i – 2} + P_{i – 1}P_{i – 2}G_{i – 3} + … + P_{3}P_{2}P_{1}P_{0}C_{0}$

But how exactly are carry bits computed in a parallel fashion for a parallel adder? I am having trouble with the grouping. I know that in a typical arithmetic expression like the one below:

$a + b + c + d$

We can group in the parallel fashion:

$(a + b) + (c + d)$

But how are the terms in the $C_i$ formula grouped? Especially since the first step of the adder is to generate all the individual $P_{i}$ and $G_{i}$ units but the terms in the $C_i$ have a lot of $P_{i}$ and $G_{i}$ combined together.

air travel – Flying with a desktop computer (as checked luggage)

I personally would take some precautions. First of all, make a backup of your data. Leave on in your home and take another one with you so that you can use it in your destination place. Then when transporting a desktop computer, the most fragile part is almost always the hard disk drive. So I would dismount it if possible and take it into your cabin luggage. You could also do this for other sensible parts like for example other drives, the processor, or the RAM bars. This I would pack into anti-static bags and take it into the cabin.

The tower itself you can put into protected pc transporting bags like this one. This bag will be checked so that you can’t smuggle and weapons or drugs. But you shouldn’t normally fear that this will damage your computer.

And last but not least, you could also think about sending your computer with a carrier. I quote this from a message board:

Send it via a Secured Carrier, RPS(Royal Packaging Service), Which
Delivers Things in the most pristine state Possible. Door to door
Service, White glove care. But i warn you, Its pricey. 15lb =
$200/USD.

computer architecture – what is difference between speculation & prediction?

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grub2 – Computer stops during boot sequence, boot-repair did not work

Hello fellow ubuntu users,

I am using 20.04 on this computer. it was shutdown normally and next day did not complete boot sequence. I tried using a start up disk to do boot repair, the dump from that utility is here: https://paste.ubuntu.com/p/StNQQcQFvK/

Please let me know if you need more details, I will provide.

thanks for looking.

computer vision – A few questions regarding simCLR

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math – Why is What Every Computer Scientist Should Know About Floating-point Arithmetic considered mandatory reading?

What Every Computer Scientist Should Know About Floating-point Arithmetic is widely considered absolutely mandatory reading for every programmer. Why is this the case? What aspects of the article make it stand out as still being important to this day?

Upon my reading of it, I found that a lot of is was only concerned with mathematical proofs and memory-level implementations of floating-point arithmetic. Aside from the general points that floating-point arithmetic is neither precise nor associative – a pair of facts that could fit on a single page – I see little reason why the article is of significance to anyone who is programming in any language where memory management is largely not done by hand. Why would say, a Java programmer, care?

windows 10 – Will giving permissions and ownership to the administrator group also give permission to administrators on a different computer?

Say I set a file to have full control permission and ownership for the Administrators, if I transfer this to another computer with a different device name, will the file also have full control and ownership for administrators on that computer? If not, will changing the device name to the same as the original computer, make this the case? I ask because the administrator group has the device name before it, like this.

power – Looking for an adaptor to use my computer from France in Uruguay

Uruguay uses 220V at 50Hz mains power supply similarly to European countries. The plugs are mostly type F, commonly known as Schuko:

Type F power plug

Or type C, commonly known as Europlugs:

type c socket
(source: worldstandards.eu)

Coming from France, this means that in most cases you will not need an adaptor. However, you might find other types of sockets – type I and type L – for which an adaptor is required. This assumes that you are using appliances with type F plugs.