Wikipedia:Reference desk/Archives/Computing/2013 May 23

= May 23 =

AutoCAD 3D Modelling
Hello :) I am currently using AutoCAD 2013 version for mac for 3D Modelling.

I have a question regarding 3d Blocks which can be downloaded from the web and inserted into a 3D drawing in AutoCAD

If I download a 'free' 3D dwg. Block from the web then explode it and create a 'new' wblock, will this remove the 'original' block reference (info) and the origin which it came from?? If no, but there is a way to delete the origin of the block could you please let me know :)

Please help!27.253.64.230 (talk) 08:37, 23 May 2013 (UTC)


 * I am only familiar with 3ds Max and Maya, but I see no reason why individual models in AutoCAD would store information on where they came from etc; especially if you are importing these blocks into an already existing project (or a new one you just made.) Once they are in your project, there shouldn't be a way of knowing where they came from. --Yellow1996 (talk) 01:03, 24 May 2013 (UTC)

Switch mode transformers
I guess this isn't really a computer question, but are switch mode transformers for mobile phones etc. cheaper to manufacture than those big fat old-timey traditional transformers? I'm guessing they are, otherwise you'd never see 'em. — Preceding unsigned comment added by 93.96.113.87 (talk) 09:49, 23 May 2013 (UTC)


 * Yes they are now, automatic component placement and the cheapness of silicon components make up for the added complexity unless the power requirement is very low, say an Amp or less. Also you shouldn't ignore transport costs on bigger and heavier things. We have an article about them at Switched-mode power supply. Linear transformers still have some specialist advantages, they're not going to be used on the national grid anytime soon!, but even where a very quiet supply is required switch mode supplies are now making inroads. Dmcq (talk) 10:23, 23 May 2013 (UTC)
 * AC adapter has more on the other user cost of a linear transformer and the reason governments want them mostly gone, they eat up more power when the device they are supplying is switched off. Dmcq (talk) 11:25, 23 May 2013 (UTC)

Text emails and hyperlinks
Is there a preferred/recommended way of putting http-links in text only (non-html) emails? Should I just paste them in an email, enclose them in '<', '>' or do something else with them? bamse (talk) 10:53, 23 May 2013 (UTC)
 * I send all my emails as non-html and I just chuck the links in as is --TrogWoolley (talk) 11:34, 23 May 2013 (UTC)
 * Yes you can paste them in. There should be no angle brackets or anything else around them as they serve no purpose. I regularly collate hundreds of plain text emails and having to strip out the angle brackets is a pain.--Shantavira|feed me 11:40, 23 May 2013 (UTC)
 * That's what I used to do as well, but then I keep getting those emails with angle brackets and thought there must be a resaon, perhaps created by a particular email program. bamse (talk) 20:33, 23 May 2013 (UTC)


 * Perhaps they do it for style? :) --Yellow1996 (talk) 00:53, 24 May 2013 (UTC)

Privacy, js and Google
When you see some js with ajax.googleapis.com (or others) in a non-Google related page, does that mean that Google knows I am visiting the page? And can it aggregate all my navigation with my visits to other pages? OsmanRF34 (talk) 12:24, 23 May 2013 (UTC)
 * Potentially, but googleapis currently sets cache options so that your browser does not reload the javascript on every page load. In other words, they can only see your first click. Also, they don't seem to set cookies for that domain, so they only have your IP address to work with. Bobmath (talk) 15:54, 23 May 2013 (UTC)

Did users of the SCELBI and computers like it have to flip switch software in manually on each power-up?
I read in the article "The book included a listing of a floating point package" and " software published in book form, including many games, a monitor, an editor, an assembler, and a high-level language dubbed SCELBAL". I don't see anything on that device but the switches and LEDs on the front, so am I correct in supposing that any user that wanted to have the machine be a floating-point calculator, monitor, game, assembler, or whatever had to laboriously flip in umpteen pages from a book and then would only have that for as long as the thing was on? What kinds of games were popular that consisted of looking at some LEDs, figuring out what they mean, and flipping some switches when it was your turn to do something? 75.75.42.89 (talk) 21:32, 23 May 2013 (UTC)


 * I'm not familiar with SCELBI, but computers of that era frequently used computer peripherals for persistent storage- magnetic or paper tape readers and printers; card readers of various types; and even hard disk and floppy disk drives. The SCELBI Product Brochure describes its audio-cassette digital interface, as well as an I/O board we might call "GPIO" suitable for hooking up any other nonvolatile storage.  And it also describes a character-mode video output capability using the "oscilloscope controller" add-on card.  There were also ASCII keyboard peripherals and other general-purpose input and output devices.  In other words, the device's human-interface capabilities were not as primitive as you may think; a lot of photos you see simply show the central control unit without any of the peripherals connected.  Nimur (talk) 22:59, 23 May 2013 (UTC)


 * Early machines that size and vintage normally used a keyboard and television for I/O and a cassette tape for storing programs and some even had a printer to print the results. The additional circutry for a television compared to an oscilloscope wasn't much so I don't see why the SCELBI went for that unless it was drawing the characters as vectors rather than dots from a character ROM. Dmcq (talk) 08:52, 24 May 2013 (UTC)


 * For most very early machines like that, you had a two-stage or even three-stage startup process. On the early versions of the PDP-11, for example, you had to key in a couple of lines of code to make it jump to the address of a small ROM that would cause it to read from a paper tape and run whatever was on it.  Generally, you'd put a small operating system on the tape (VERY small!) and from that point on you could type simple commands from a teletype to read programs in from paper tape, magnetic tape or whatever.  On some of the smaller machines like the Scelbi, ROM memory was very expensive - so you'd have to use the switches to enter a very small paper tape loader - often using the teletype's paper tape reader.  This would be a piece of software that was highly tweaked to make it easy to key in on the front panel switches - perhaps no more than a dozen bytes - so it would have no error checking or anything!  That tiny piece of software would then read a larger, more carefully written, paper tape loader, and that would in turn load whatever software you wanted to run.


 * By the time the Scelbi-H was sold to the public, they did have cassette tape loaders and ROM memory - so probably the PDP-11 approach of keying in an initial jump instruction and executing it from the front panel switches was the startup approach.


 * http://www.atarimagazines.com/creative/v10n11/6_The_early_days_of_persona.php says: "For that time, we had a very sophisticated system, a complete system. We had a tape cassette interface that actually worked a lot better than the ones MITS started selling. We had a CRT based on an oscilloscope, and Teletype interface, and we developed a combination monitor, editor, and assembler in ROM.")


 * So this was a fairly advanced machine for the time.


 * My first hand-built 8008 machine used the three-stage boot process until I could save up enough money to buy a 32 byte 'fusible link ROM' (not 32kbyte...32 byte!)...I seriously considered whether I could make my own ROM from a bunch of diodes...but sanity prevailed!
 * SteveBaker (talk) 16:31, 24 May 2013 (UTC)