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May
7
comment Do S-Video Cables Cause Cancer?
@ZeissIkon: Lead solder is popular for hobbyists not because it's cheap, but because it has much more forgiving thermal characteristics than lead-free. When electronics are assembled via automated processes or by people in a high-volume production environment, it's possible to calibrate the equipment and train the people to yield good results with lead-free solder. When one-off devices are assembled by novices with cheap equipment, however, lead-based solder works better.
Apr
21
comment Why does emptying disk space speed up computers?
@JasonC: I think the simplest way to describe GC and the trim command is to say that in GC a page becomes garbage when a new version of that page is written, but the act of writing a new version of that page will consume a formerly-blank page. Trim allows a page to become garbage without requiring that a new version be created.
Apr
20
answered Why does emptying disk space speed up computers?
Mar
29
comment Can I connect a USB 1.1 hub to a wall outlet and charge devices?
@user20574: Why would that be a problem under my proposed scheme? If a supply that's good for 1.5A feeds a hub which has two devices plugged into it which would each "like" to draw an amp, then if the devices ramp up their current demands at the same speed, both devices would get 0.75A. If the devices ramp up at unequal speeds, the distribution would be unequal but they would end up distributing about 1.5 amps between them in some fashion.
Mar
29
comment Can I connect a USB 1.1 hub to a wall outlet and charge devices?
@user20574: My wondering was about what would have happened if something such as described had been in the spec from the get-go. While some power-supply designs will respond to an excessive current demand by overheating while remaining in regulation, many common topologies will "naturally" sag under such cases, and most supply topologies can be made to sag under such cases by limiting their range of feedback. A switching supply that is limited to 5.2 watts and 5.2 volts, for example, will supply 5.2 volts at 1.0 amps, or 5.0 volts at 1.04 amps.
Mar
28
comment Can I connect a USB 1.1 hub to a wall outlet and charge devices?
I wonder if there would have been any problem with defining the USB spec to say that if the supply is between 5.0 and 5.5 volts, any device is allowed to draw up to (V-5V)*5 amps provided that its current demand doesn't increase faster than a certain rate, and provided that its current demand will be immediately reduced if the voltage falls? All one would need to make that would be a power supply whose output voltage would fall as it approached its current limit, which is something many supplies do naturally.
Mar
28
revised Why does a CPU have a clock?
added 1485 characters in body
Mar
27
comment Why does a CPU have a clock?
...if SI is available when the time comes to execute the first instruction then it should likely go first. If the SI value becomes available at the exact moment that the system is trying to decide which instruction should go first, resolving that in an asynchronous system may be very hard. Allowing out-of-order execution of some parts of the code while ensuring that things which need to be sequenced, are, is much easier in a synchronous system than in an asynchronous one.
Mar
27
comment Why does a CPU have a clock?
@MichaelKjörling: I'm aware that many programs contain a lot of instructions that may be arbitrarily sequenced, but if an architecture is going to be used to run non-trivial programs correctly, it needs to be capable of properly sequencing groups of instructions where sequence matters. Further, the question of whether an instruction should proceed without waiting for an earlier instruction must itself be sequenced. Given mov ax,[si] / mov bx,[1234], if the value of si isn't available when the first instruction is reached, it may be beneficial to run the second one first, but...
Mar
27
comment Are CPU clock ticks strictly periodic?
In some cases, the capture clock may be the second or later cycle rather than the next. Some designs assume that data will always take at least some minimum amount of time (e.g. if propagation delay is known to be between 2.1 and 2.9 cycles, data could be output and results sampled on every cycle; each sampled result would reflect the data from 3 cycles before); other more conservative designs change the output data more slowly, and ignore the result until it is guaranteed to be stable.
Mar
27
comment Why does a CPU have a clock?
@MichaelKjörling: It is common for a program to contain some instructions whose proper function won't depend on the immediately-preceding instruction, but any non-trivial program will also contain groups of instructions which must be executed in precise sequence. There are ways of ensuring consistent sequencing without using a system-wide clock, but a lot of circuitry is generally required to pass around all the necessary timing signals, and the speedup obtained would be less than could be obtained by using that same amount of circuitry for some other purpose in a clocked system.
Mar
27
answered Why does a CPU have a clock?
Mar
18
comment Why I have to press keys two times to get the ^ or ´ or ` symbol in Windows 7 and how can I fix it?
@DavidMulder: Since I installed my keyboard layout, I'm happy with the way the keyboard works. I can type résumé, l'hôtel, etc. much more nicely than with the US layout, but all of the "normal" keys work as they should. It just seems that people wanting a sensible keyboard layout should have an easier course of action available than downloading the keyboard creator, editing the keyboard "source" file, and compiling it to an installation application.
Mar
17
comment Why I have to press keys two times to get the ^ or ´ or ` symbol in Windows 7 and how can I fix it?
@DavidMulder: This question seems to have come up so often that I wonder if there's any "trusted entity" who could compile and host a utility to install a fixed keyboard layout (since the only way to install a new keyboard layout is to run an installer created by the keyboard-editor software!). I'm not claiming any special skill at layout design, but I'd say the things mine switches a few things MS just plain got backward.
Mar
17
comment Why I have to press keys two times to get the ^ or ´ or ` symbol in Windows 7 and how can I fix it?
@DavidMulder: altGR is harder to hit, but most people in the US type apostrophes and quote marks a lot more often than they type aigus and umlauts; many (esp. programmers) type carets and backticks more often than circumflex and grave accents. Using one layout all the time and hitting altGR when accents are needed seems much easier and safer than having to worry about what layout is active at any given time.
Mar
17
comment Why I have to press keys two times to get the ^ or ´ or ` symbol in Windows 7 and how can I fix it?
Any idea why MS didn't make altGR+quote, altGR+shift+quote, altGR+shift+6, and altGR+grave work as dead keys, while leaving the normal ASCII-generating keys alone? Apple figured out how to do that in the 1980s. The deadkey behavior is horrible, especially given that deadkeys remain pending after cursor moves.
Jan
19
comment Why are we still using CPUs instead of GPUs?
@vartec: I think a slightly better analogy might be between buses and taxicabs. If there are forty people who all want to go from the same place to the same place, a bus will be much more efficient. If there are forty people whose desired origins and destinations are widely scattered, even a single taxicab may be just as good as a bus, and for the cost of the bus one could have multiple taxicabs.
Jan
15
answered “Turn off router for 10 seconds” - Quantifiable?
Dec
26
comment What is causing my hard drive's click of death?
Not only was using a separate platter for servodata inefficient, but I think it also became insufficient, since I believe hard drive tracks are so dense that differential expansion or other variations between platters and heads mean that different platters might require slightly different head positions to read tracks on the same nominal cylinder.
Dec
8
comment What is the value of MD5 checksums if the MD5 hash itself could potentially also have been manipulated?
An MD5 checksum transmitted via some path other than a file itself would provide protection against tampering unless the file was deliberately created to facilitate such tampering. By contrast, something like CRC32 would provide almost no protection against tampering even if the original source of the file was trustworthy and the CRC32 was delivered securely.