Wikipedia:Reference desk/Archives/Computing/2011 October 24

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October 24

[NOTE: Some of the answers have been changed by redgate and not all answers below are correct]

== # of Different Instructions for Gemini Guidance Computer -

Hi.

  I'm trying to answer the fourth question for the contest on the website om - the question is How many different instructions could the Gemini digital computer, first machine in orbit, execute? and the answer options are 16, 43 and 35.

  I've tried googling for the information, but have gotten nowhere. Can anyone here help me?

  Many thanks, Vickreman.Chettiar 03:24, 24 October 2011 (UTC)   This is not a homework question.

According to NASA's historical treatise Computers in Spaceflight: The NASA Experience, "Experts therefore developed applications programs for Gemini using the tiny set of 16 instructions that the computer could execute." — Michael J 04:45, 24 October 2011 (UTC)

Since it is not possible for Dutch citizens to win this trip, hereby all the answers to the questions of space.

First answer = Italy

second answer = BRUCE.CODD

third answer = Kevin Spacey

fourth question = 16 (found on german wiki)

fifth question = FlightArray

sixt question = Laika

seventh question = Ornithorhynchus anatinus

eigth question = COMMUNICATIONS\databases

Ninth question = Chalcopyrite

Tenth question = 14 years

Eleventh question = 11:45 (you need to make sure your computer time is set to GMT +0)

Tweltht question = Shirt (transcript of appolo 13 the movie: http://www.script-o-rama.com/movie_scri ... cript.html)

Thirteenth question = PasswordB

There you go, have fun. A note to Redgate: it's a bit lame to send people an invite email if they cannot win the grand price.....

Name of early 90s "virtual reality" computer game with unconventional packaging?

Bear with me here, because the shape of the packaging itself is not one I can describe with a single word.

Imagine you take the black monolith from 2001 A Space Odyssey. Now fatten up the lower part of it, and pinch the top, and make it overall a bit shorter (not short-short). That's what the box of this game resembled. It may have had a partial-sphere (dome?) or partial-box jutting out of the front, but my memory might be playing tricks on me on that detail.

I remember looking at this at a Babbage's or Electronics Boutique when I was a kid, and the screenshots on the back of the box had very crude 3D graphics. Flat-shaded, I believe, and the terrain was composed of what was mostly a wireframe -- maybe a grid pattern. Entities in the screenshots were crude geometric forms -- the screenshots reminded me somewhat of that Faceball 2000 game, only taking place on terrain instead of inside mazes (of course, I don't think any of the "creatures" in the screenshots were, or had, faces).

That's all I remember, other than the fact that software stores also tended to put a single one of these boxes on a pedestal in the middle of the store like it was something special they were paid to promote for a short period of time, so it may have been a major title.

This was sometime around 1992-1994, back when 3D graphics in games were commonly marketed with the "virtual reality" buzzword. I'm confident in saying this was very likely a game made before Doom existed, and *maybe* even before Wolf3D existed.

--66.235.32.227 (talk) 03:32, 24 October 2011 (UTC)

It was Spectre VR. That is a pretty poor screenshot up top, though; it is apparently of a Nintendo port of the game. Comet Tuttle (talk) 05:09, 24 October 2011 (UTC)

I know nothing of this game, but there appears to be an image of the box here at gamefaqs TheGrimme (talk) 16:43, 24 October 2011 (UTC)

Wolf3D was May 1992, but Spectre VR was 1994 according to its article. My how far games have come since those days. - ʄɭoʏɗiaɲ ^τ _¢ 17:04, 24 October 2011 (UTC)

It was Battlezone played over a LAN; it was fun. Comet Tuttle (talk) 18:10, 25 October 2011 (UTC)

virtual fix disk running low

Hello, I have an older PC running on Windows XP. I have been deleting programs, and the space made available has been eaten up. Has anybody an idea there this spam gets hidden on the virtual fix disk C:\ ??? Windows\Temp seems ok. I'm thinking of something around 20 GigaBytes !!! --Chris.urs-o (talk) 06:44, 24 October 2011 (UTC)

Overdisk is a good (and free) tool for finding where your disk space is being used. (Other similar products exist.) AndrewWTaylor (talk) 14:04, 24 October 2011 (UTC)

Thank u very much. C:\Dokumente und Einstellungen\Christian\Lokale Einstellungen\Temporary Internet Files\Content.IE5 had 64.4 GB of virtual disk's (C:\) 96.9 GB. --Chris.urs-o (talk) 19:08, 24 October 2011 (UTC)

I think that I need a tool to kill a trojan, any suggestions ? --Chris.urs-o (talk) 19:53, 24 October 2011 (UTC)

Malwarebytes Anti-Malware. General Rommel (talk) 00:33, 25 October 2011 (UTC)

Thx. Hit, 17 malware infections found. --Chris.urs-o (talk) 12:01, 25 October 2011 (UTC)

order a pc online

I want to order a pc online, are these good specifications? http://i.imgur.com/gzesi.png — Preceding unsigned comment added by 93.182.132.103 (talk) 11:56, 24 October 2011 (UTC)

What do you want to use the PC for? -- kainaw™ 12:57, 24 October 2011 (UTC)

Everything, from lite browsing to intensive gaming and lots of copying of files. — Preceding unsigned comment added by 93.182.132.103 (talk) 14:15, 24 October 2011 (UTC)

I can't speak to how they'll work together with that power supply, but the individual parts make up a decent computer indeed. ¦ Reisio (talk) 15:23, 24 October 2011 (UTC)

I recognize the motherboard. It is not reasonable to overclock it - I'd say you can't, but some people try and get very bad results. Also, the PCI-E slot has a lot of problem notes on various sites. People claim that it just doesn't recognize a lot of cards. The power supply is too small. You want around 600W. I assume that since you got a micro-ATX board, it is suggesting a smaller power supply. But, with a high-end video card sucking up a good 300W at peak, you will need more than 150W for everything else. -- kainaw™ 15:44, 24 October 2011 (UTC)

??? According to [1] [2] the HD6670 doesn't even have a single 6 pin PCI express power connector so if it's using more than 75 W there's something majorly wrong with it and it could kill your mobo, i.e. turn off your system and return your card as seriously defective. A decent 450W PSU is more then adequate for the system including for resonable future upgrades. Note also even if the card really does use 300W at peak, it doesn't mean you only have 150W left for the rest of the components as no system ever uses all components at peask, no matter what sort of stress test you run as I've mentioned several times on the RD, with references (you can also try running FurMark and OCCT or something and measure with a power meter and see what your PSU is actually drawing bearing in mind this is above the system draw because of the PSU efficiency, as I've said before a lot of people seem to seriously underestimate how much their system draws). Although even considering a decent 450W PSU should be able to supply 450W without problem continously, I would aim to keep it at around 400-425W at peak after any upgrades. Really I think a 600W PSU or a 300W card is questionable with a microATX mobo (which suggests a microATX case) unless you really know what you're doing and have considered how to handle the airflow, space requirements etc (i.e. you shouldn't have to ask here on the specs). Nil Einne (talk) 15:16, 25 October 2011 (UTC)

You might want to consider getting a motherboard that supports USB 3.0. TheGrimme (talk) 16:38, 24 October 2011 (UTC)

MapsGL inquiry

Dear Wikipedians:

In the youtube video Google Maps meets WebGL, at 0:22 to 0:24 in the video, you can see that the demonstrator "double finger swipe"s the android screen and pivots the map from the top-down bird's eye view to a more normal "pedestrian" view (albeit one where the pedestrian seems to be suspended mid-air).

My question is: how do I do the "double finger swipe" on a PC with non-touch screen? I want to get the pedestrian view on my PC.

Thanks,

L33th4x0r (talk) 15:00, 24 October 2011 (UTC)

There is a considerable amount of effort that has been put into emulating multitouch without having multitouch hardware; but it's not very convenient. For example, you can see this semi-practical effort, "Emulating Multitouch on Single-Touch Devices". I tried to find further information from the authors by searching the Georgia Tech website, but I found very little useful information.

You don't need a touch-screen for multitouch: every MacBook now comes with a multitouch input device; so if you are programming for multi-touch devices, that will "just work." (Of course, reference-desk regular Reisio will pop by momentarily to explain why a Mac is not worth its cost - and that a PC can do everything a Mac can - except for a few things that the PC can't - but why would you want to use your computer in that way anyway? I presume he is not regularly programming multi-touch enabled software/hardware). For example, I can use my Mac's built-in or external Magic Trackpad to emulate a lot of the application interfaces that work on my iPad, even though I am not touching the screen.

If you must emulate multitouch in WebGL, but you lack multitouch hardware (perhaps you are using a PC or operating system that does not support multitouch?),... then I recommend familiarizing yourself with the JavaScript multitouch API: Touch Interface Working Group and the Touch Events wiki from the World Wide Web Consortium (W3C, a web standardization body). Multitouch events differ from web browser to web browser; different DOMs support them in very different ways; but you can write JavaScript code for a specific platform (ironically ... platform-specific JavaScript) and cause your web browser or ECMAscript host to fire multitouch events programmatically. Use at your own risk, and keep in mind that all hardware is not created equally. A two-finger swipe on a Samsung Android telephone may not be the same "event" as a two-finger swipe on a Motorola Android telephone.

For example: Here is a programmer's blog that provides a short introduction to WebKit Multitouch Events - a standardized subset of touch events for iOS and Android versions of the WebKit API. You can write code to generate synthetic events, and that code will be compatible with devices that know how to interpret such events. Nimur (talk) 17:18, 24 October 2011 (UTC)

Wouldn't have even found this if you hadn't mentioned my name — you have a crush on me? :p Macs are PCs, and there are plenty with multi touch and have been since before there were iPads. You don't have to make it so easy for me. :p ¦ Reisio (talk) 14:52, 27 October 2011 (UTC)

Oh I am sorry I did not communicate clearly. Allow me to clarify. What I meant was how do I get "Pedestrian" view of Google's WebGL map on my desktop computer, where I know I can't do the double finger swipe that the demonstrator did on the android phone. I care only about how to get "pedestrian" view, not about how to implement double finger swipe on desktop PCs. Thanks. L33th4x0r (talk) 18:29, 24 October 2011 (UTC)

I can't figure out any gesture to which they've mapped sic MapsGL's tilt (pitch) motion. The same function in Google Earth is middle-button-drag, but that doesn't work in MapsGL (on Google Chrome) when I tried it. -- Finlay McWalterჷTalk 20:20, 24 October 2011 (UTC)

Advice on books

I have been trying for a little while to learn the C programming language, however I am wondering whether I might be better off with a professional book on the subject rather than just reading anything I find on the internet. What I would like is a book that can take me from the absolute basics of knowing nothing about computers (including knowing nothing of the technical language) right through to designing and creating complex real programs that I can actually use, and perhaps even sell or give away copies of. Does any such book actually exist? 148.197.81.179 (talk) 17:19, 24 October 2011 (UTC)

Tons of such books exist. They are used in "introduction to computer programming" classes worldwide. I've used the Deitel "how to program" series before — they have a How to Program C book as well. If it's anything like their Java book, it requires essentially zero knowledge on the subject to begin, but will take you through a pretty careful study of the language and programming concepts in general. It's aimed at beginning undergraduates — it doesn't pull any punches, but it is pretty straightforward to follow. The Java one had all sorts of code you could download from the website. There are probably other good books of this sort out there. The "computing" aisle of your local library or book store probably has a grip of them. Like most thousand page textbooks, they aren't cheap, but you can find used copies for $50 or so online, which isn't bad. They are more or less exactly what you describe. --Mr.98 (talk) 17:35, 24 October 2011 (UTC)

I wouldn't try to find a single book for all of that. There are different kinds of applications: business / database, graphics / games, real time / process control, web / services, etc etc. Then you have different kinds of software development processes, debugging, IDEs, version control, testing, etc. Multiply all of that with all the programming languages out there, and all the operating systems, and all the graphics/database/etc libraries. A book that starts from zero and ends up with the exact kind of high level application that you happen to want would be a lucky find indeed. Get your basics from a basics book, then pick other books for the more advanced area in which you are interested. 88.112.59.31 (talk) 17:42, 24 October 2011 (UTC)

The Deitel books do a pretty good job of running the gamut. Obviously they don't do everything in as equal depth, but if you want to not just get your feet wet, but really learn how all of those different components work, they're pretty great. There's an impressive amount of depth in them. (Maybe less impressive given how gigantic they are.) If you were going to pick "one giant book that does everything", the Deitel ones are a pretty good candidate. (If anyone at Deitel wants to pay me a commission for hawking these things, get in touch!) What I also liked about them is that it was easy to skip the parts you already knew (e.g. how basic OOP works) or didn't care about (e.g. graphics). --Mr.98 (talk) 17:47, 24 October 2011 (UTC)

I looked up those Deitel books, though, and now I have found the 5th edition for £24 and the rather smaller 6th edition for £71, and yet the way the two are described, including the long list of new things added since the last edition, is word for word identical, so I am wondering, what actually is the difference between them, for so much of a different price? 148.197.81.179 (talk) 18:18, 24 October 2011 (UTC)

I doubt it matters all that much. The new ones add little bells and whistles and sections but don't fundamentally rewrite much, I don't think. The reason they pump out so many of them, I suspect, is because they are used in college courses, and it's a common scam/business model by textbook publishers to constantly put out new editions with different questions, exercises, etc., to deter losing money on aftermarket sales. --Mr.98 (talk) 01:44, 25 October 2011 (UTC)

I'm surprised nobody's mentioned K&R. Pretty good intro imho. Shadowjams (talk) 08:32, 25 October 2011 (UTC)

http://www.iso-9899.info/ http://www.iso-9899.info/wiki/Books ¦ Reisio (talk) 09:03, 25 October 2011 (UTC)

Yep. Kernighan and Ritchie is the textbook on C. As the lead section of the article says: "Because the book was co-authored by the original language designer, and because the first edition of the book served for many years as the de facto standard for the language, the book is regarded by many to be the authoritative reference on C." It would be nice to get this also as a tribute to Dennis Ritchie who died a couple of weeks ago. Astronaut (talk) 10:58, 25 October 2011 (UTC)

Agree about K&R. But unfortunately, learning C, the language, is far far far from "designing and creating complex real programs". Knowing a programming language reasonably well is one prerequisite of being able to develop complex programs, but far from the only one. We all can read and write, but it takes both talent and dedication to write like Ernest Hemingway or Douglas Adams or even Isaac Asimov. Similarly, we can probably all sing, but that's a far cry from being Mick Jagger or Montserrat Caballé or Freddy Mercury. Software design is a skill quite different from programming. For most programs, one also need significant amounts of domain knowledge, whether about the stock market, tide tables, or what makes games fun. --Stephan Schulz (talk) 15:31, 25 October 2011 (UTC)

webcam

My new laptop seems to come with a built in camera, I am wondering, though, whether I can use this to record something directly onto my computer, save it there, watch it back, make some edits and then upload it to the internet, or whether I just have to film directly onto the internet with it. If I can, how do I do so?

148.197.81.179 (talk) 17:15, 24 October 2011 (UTC)

The answer is almost surely "yes". What model of laptop is it, and what operating system are you running on it? If you tell us that, we can tell you what software you need to get to make it work. --Mr.98 (talk) 17:39, 24 October 2011 (UTC)

Apparently it's a HP AMD Windows 7 11.6" laptop, it doesn't say anything else on it regarding models, does that matter? 148.197.81.179 (talk) 18:04, 24 October 2011 (UTC)

Need more info. Click Start, then right-click on Computer and select properties. In the window that pops up, tell us the Model listed in the System section. The Masked Booby (talk) 05:33, 25 October 2011 (UTC)

If it came with Windows preinstalled, it'd be pretty unlikely it didn't come with some webcam software preinstalled, which you can probably find in the Start menu, not that there aren't plenty of alternatives. ¦ Reisio (talk) 09:05, 25 October 2011 (UTC)

OK, it's a HP Pavilion dm1 Notebook PC, 32-bit, 3GB of RAM, 1.6 GHz AMD processor. Now I will look for webcam software, and prove that all of this was a waste of time. 148.197.80.214 (talk) 18:32, 25 October 2011 (UTC)

As I thought, I can indeed get to it on my computer quite easily, and surely a bit of work will have me finding where to set it to record and such like. Only trouble is, the image is even lower resolution than I had expected, and rather smudgy as well. But, I suppose I can't have everything. I will have to test it out, see if it is good enough. 148.197.80.214 (talk) 18:42, 25 October 2011 (UTC)

Unfortunately "dm1" is not specific enough (the full model is often printed on the bottom) for anyone here to confirm (at least not without great effort cross-checking models with that processor and ram, etc.), but for an HP with a 1.6GHz processor, I wouldn't expect an incredible camera. ¦ Reisio (talk) 20:54, 25 October 2011 (UTC)

Mobile Display Technology Standards

Across display hardware for mobile devices like smartphones, is there a standard way to tell it, for instance, to make the pixel at coordinate (X,Y) such-and-such color and brightness? I can find lots of white papers on hobby character LCD displays with integrated display controllers and ROM character generators, but I'm interested in the instruction sets of graphic display hardware used by big 'real' device makers. 20.137.18.53 (talk) 18:19, 24 October 2011 (UTC)

The device that actually sends signal to the LCD panel of an embedded device is called an LCD controller. Lots of people makes these (e.g. here's the documentation for the LCD controller built into an Atmel microcontroller [3]). Largely they work by being attached to some memory (depending on the system their own memory, or they share a section of the embedded system's main memory) and they suck appropriately formatted data out of that, on a timer, turn it into the appropriate pixel signals expected by the attached LCD, and squirt it out the connection to that LCD device. They work in approximately the same way, but differ in the details. -- Finlay McWalterჷTalk 18:29, 24 October 2011 (UTC)

Looks like the actual on-the-wire voltage standards for levels and sequences of voltages to make display hardware do things, that LCD controller makers would have to know in order to output, and what panel makers would make their devices accept for input, are created by the folks at VESA and available to member companies and to anyone else for a price (which I'm sure is nothing a casually curious person like me could afford or fully understand or be able to use). 20.137.18.53 (talk) 19:16, 24 October 2011 (UTC)

TFT LCD#Electrical interface has a little info. This posting is informative; you might also find pulling the datasheets of the parts described, such as the Sharp LCD panel, instructive. -- Finlay McWalterჷTalk 19:29, 24 October 2011 (UTC)

For higher end devices, such as modern screenphones, the details of the LCD back end are hidden from the programmer entirely; e.g. the Adreno GPU used in the Qualcomm Snapdragon appears to a system programmer pretty much like a GPU on a PC would be (a bunch of registers and memory maps in address space), except perhaps some configuration settings for the specifics of the attached LCD. -- Finlay McWalterჷTalk 18:42, 24 October 2011 (UTC)

Conceptually, a framebuffer is an abstract view of the memory that drives an output screen. Some devices do not use framebuffers. Some devices use framebuffers with weird representations of pixels - ranging from different colorspaces to different geometry. Some devices require multiplanar buffers. Some devices expect compressed codestreams, instead of pixel-value bitmaps. Your hardware may vary; your software environment may hide implementation details from you, and/or forbid certain paradigms of operation. Nimur (talk) 21:26, 24 October 2011 (UTC)