Wikipedia:Reference desk/Archives/Computing/2016 July 17

= July 17 =

My SPI OLED Module has no CS pin
I tried to connect a 0.96" 128x64 monochrome OLED display to my Arduino Nano.

http://www.electrodragon.com/product/0-96-12864-oled-display-iicspi/

They look like the ones on this page even though their backs are a little different.

I purchased each of both types. The I2C OLED worked as advertised but the I2C/SPI one has some issues.

The OLED shown on the webpage has 7 pins while mine has only 6 pins. Mine has all the pins except for CS (Chip Select).

My I2C/SPI module has soldering pads in its back that says "I2C" and "SPI" and the SPI pads are shortened by its manufacturer. Unless I desolder them, its I2C interface is disabled. It does not provide any clue regarding its I2C address. Either 0x78 or 0x7A, I guess. I'll probably never use its I2C mode.

My I2C module with an address of 0x78, has a 470k resistor soldered between the 0x78 bonding pads in is back side. This resistor can be detached and soldered on the 0x7A pads. It's painful to work on these itsy-bitsy SMT parts. But at least I can still manage to have two of them on the same I2C bus.

Does it mean my I2C/SPI OLED module will always have its SS (select) line set at low?

Does it mean I can never use two of these I2C/SPI modules on the same SPI bus? -- Toytoy (talk) 03:13, 17 July 2016 (UTC)


 * By the way, these OLED modules are not defective. They were custom made for their particular customers. That's why there are so many similar OLED modules on the market with similar but different circuit board designs. They were built for special purposes and unshipped productions went to the hobbyists. They are badly documented at best. Some of them have no documentation at all. -- Toytoy (talk) 04:07, 17 July 2016 (UTC)


 * I daresay you can use GPIO pins on the Arduino as outgoing CS pins, and AND these (with external glue logic) to each display's drop of the I2C bus (which is effectively how chip-select would work if the displays themselves had a CS pin). In any event, the I2C address space is so small you can resort to bruteforcing to figure out what address a specific part has. -- Finlay McWalter··–·Talk 21:26, 17 July 2016 (UTC)

Files that I have deleted and thrown in the Trash-can, only to empty the trash-can afterwards, is it possible to recover those files ?
Files that I have deleted and thrown in the Trash-can, only to empty the trash-can afterwards, is it possible to recover those files ? If so, how ? Tell me step by step if you're willing.

Thank you. Krikkert7 (talk) 06:51, 17 July 2016 (UTC)


 * The first place to look is on your backup media, but if that is somehow not available then you might like to try something from our List of data recovery software. Before you do anything else, stop saving any files to the drive from which the files have been deleted because these might overwrite the space where your deleted files were stored.  There is no guarantee that the deleted files will still be there, but PC Advisor recommends Disk Digger and PCWorld recommends Recuva.    D b f i r s   08:02, 17 July 2016 (UTC)


 * Note that stop saving any files implies stop using any application that tacitly saves files; for example, your browser saves history and cache... —Tamfang (talk) 07:01, 20 July 2016 (UTC)

Thank you Krikkert7 (talk) 12:15, 17 July 2016 (UTC)


 * It depends how badly you want the data back. For critical data, there are professional data recovery services but they are not cheap. Much more expensive than the cost of a backup disk. If you do want to go down that route, stop using the computer immediately. Vespine (talk) 00:39, 18 July 2016 (UTC)

Binary Calculation
While doing binary calculation such as : 11001+110*101011 Can we use BODMAS rule here or not? — Preceding unsigned comment added by Sahil shrestha (talk • contribs) 13:57, 17 July 2016 (UTC)


 * In the absence of any indication of a left-to-right convention, one would assume that algebraic order of operations (BODMAS) is appropriate. For clarity, brackets (parentheses) should be shown when the calculation is not obviously algebraic.    D b f i r s   15:54, 17 July 2016 (UTC)


 * In mathematics, the normal order of operations always applies when arithmetic operators are applied to numbers. It doesn't matter how the numbers are written (decimal, binary, hex, or balanced ternary for that matter). However this is the computing reference desk. If you're asking whether the order of operations applies in some particular programming language, you'll need to specify which language you're using. Almost all programming languages use the BODMAS rule too, although there are exceptions like APL and Smalltalk. CodeTalker (talk) 16:26, 17 July 2016 (UTC)
 * It doesn't even matter if + and * are actual addition and multiplication rather than, say, bitwise OR and bitwise AND (I don't know enough math but I'm sure deep down + and OR and similarly * and AND, are one and the same operation, or are special instances of some third operation. It isn't called "sum of products" and "product of sums" for nothing!) Asmrulz (talk) 23:32, 17 July 2016 (UTC)

Current existence of InterNIC
Does anyone know about InterNIC? Please go to the discussion at Talk:InterNIC --Quest for Truth (talk) 17:48, 17 July 2016 (UTC)


 * The root name server that formerly operated under the name "InterNIC" is now operated by Verisign. It probably lives in a giant data center in McLean, Virginia, with the rest of Verisign's (and their friends') internet backbone hardware.
 * I doubt that very much of the server infrastructure has been physically located at 333 Ravenswood Avenue since the 1980s, so this transition was probably mostly an administrative transfer. One could probably make the case that the major backbone operators are, de facto, the new root-level arbiters, anyway, so it's almost moot to discuss who controls the root name servers and routing tables.  As far as InterNIC itself, it always was, and still remains, a registered service mark (not an organization).  The mark is assigned to the U.S. Department of Commerce (a part of the United States Government) and is administered by ICANN, which is a special organization that still exists and has special operational involvement with the basic technology and policy infrastructure that most people call "The" Internet.  Nimur (talk) 20:28, 17 July 2016 (UTC)


 * Nitpick: as the article says, most of the root "servers" are actually a bunch of servers spread around the globe using anycast. --71.110.8.102 (talk) 06:04, 18 July 2016 (UTC)
 * Thank you, User:71.110.8.102, for your perfectly correct observation. The technical implementation of the domain name resolution system has become quite a bit more complicated nowadays compared to the "vanilla" description in textbooks and the original RFCs.  I trust that our technically-apt enthusiast readers can dive deeper into those details.  Appropriate starting points for anyone new to the topic are our articles on the Domain Name System, the Internet Protocol, and new users just need to be aware that this technology is very complex and has evolved considerably over the decades.
 * Nimur (talk) 15:34, 18 July 2016 (UTC)

Thanks all of you! Can I say that the organization ceased to exist in 1998? I'm adding the article to Category:Organizations disestablished in 1998.--Quest for Truth (talk) 16:19, 20 July 2016 (UTC)