Is Checksum or CRC better for checking data written to USB flash drives?
This post is to give the general user an idea of what verification method is better for writing data to a flash drive. There are reference links at the bottom of this post which dive much deeper into the two methods of verification if this simple overview is not enough.
The short answer is Cyclical Redundancy Check or CRC is the best method for checking data written to a USB flash drive.
Many believe a checksum is the best method to verify data written to a flash drive (most popular is MD5). I believe this is favored because it is easier to understand how the verification works, and also easier to implement. However, there are flaws in checksum verification and therefore not suitable for verification of data written to a flash drive.
What is the difference between Checksum and CRC verification? The checksum method uses addition in its math calculations to check whether all data was written correctly. CRC uses long division in its math calculations to check whether all data was written correctly. It is worth noting I am talking about binary long division, not the school-yard long division you so fondly remember.
Checksum methods will calculate the total
Minecraft has taken on a life of it’s own. From 5 year old kids being obsessed with Minecraft to adults making movie trailers it’s a strange little obsession for digital lego’s that look like CAD drawings.
Either way, you might find this post useful for how to make a portable Minecraft USB stick. With a portable version of Minecraft you can now play the game anywhere, school, library, work, you name it.
This is how you do it:
(Download Portable Minecaft rar now)
- Download portabal_minecraft.rar
- Extract Minecraft folder to Memory stick *Need program to extract .rar file, just Google “extract rar”
- Open the Run.exe
- Log into your Minecraft account and let it update for you
- That’s it!
The resultant USB will have several items in the root of the USB.
- .minecraft folder with all your assets
- Minecraft exe file which is the program
- Start.bin file, which generates Minecaft when you start
Did this help you?
The Alesis IO Dock is a great product for iPad musicians – this small hack makes it even greater. It overcomes one limitation of the IO Dock: You can’t simply hook it to a USB hub. So I decided to build in an additional hub – which allows me to hook up additional class-compliant interfaces like my M-Audio Axiom master keyboard, and power them via the hub.
Yes, it works. No, it hasn’t been thoroughly tested yet. So try at your own risk.
Full Tutorial (nice)
Instructables member TLevis posted a cool tutorial on making a webcam controller from a 3D printer. Since 3D printers are all the rage right now, lets spread the word. It’s a cool design, but overlooks the ability to move the camera up and down…as it only rotates left and right.
Read up on the tutorial via Instructables.
I read a great article on The Unofficial Apple Weblog [TUAW] about making a Mountain Lion installer on USB.
To make an installer version of Mountain Lion on USB you’ll obviously need a copy of the OSX Mountain Lion installer.
Next, go to your applications folder and find the actual installer…should be called Mac OS X Mount Lion.
Rich click that bad boy and select the Show Package Contents form the pop-up.
Navigate to Contents > SharedSupport and then start looking for the InstallESD.dmg. This is the image file for the installer.
Now we need to launch the DiskUtility so open a new folder with Command N.
How To Read CID on SD card
If you are looking to read the CID number of an SD card, or extract the CID off an SD card then you’ve find this article very helpful. Some also call this “reading the PSN off the SD card” or reading the product serial number off the SD card.
Most phones and much of the software on phones will lock in to the CID number of a SD card. The CID number is a unique card identifier number that is unique to the card itself. The CID number is valuable because software developers and hardware developers can lock software to the unique number of the device thus eliminating the ability to pass along licensed software.
Reading the CID number from an SD card is not an easy task. It requires specific access codes to the index table of the memory card, and unless you know how to use the SD chipset of your card reader, chances are you wont get the number…or least the correct and accurate number.
What is the CID number of an SD card?
The CID register is 16 bytes long and contains a unique card identification number. It is programmed during card manufacturing and cannot be changed by SD Card hosts. The CID number is a compilation of information about the card, such as manufacturer, date manufactured, checksum total, GB size and more. Below is a table outlining all the items which make up the SD CID number.
So with all this said, how do you read the CID number from an SD card? As we’ve mentioned it isn’t easy and it’s [more or less] hardware based. If you do enough searching on the internet you’ll find some home-brew code to read the CID numbers, but that’s only if you have the SD card or microSD card connected via an IDE bus to your host computer. This isn’t easy for everyone. There is clear evidence that using a USB to SD card reader will not get you the information you require, or at least accurate and correct information. Meaning most times the CID number generated is actually the serial number of the card reader itself, not the CID number of a specific SD card.
In addition, what if you are required to read the CID number off SD media in bulk? A single, one-at-a-time solution is not practical.
In my search to read the CID number from SD media, I cam across Nexcopy – a manufacturer of USB duplicator equipment and other flash memory equipment. Several models they carry are SD duplicators and microSD duplicators. With the secure digital duplicators part of their feature set includes reading CID numbers from SD media. The equipment can ready 20 cards at a time, 40 cards at a time, or 60 cards at a time, depending on the model. The duplicators will read the CID number and exported to a .csv file for import into other business functions. This configuration makes it quick and easy to obtain the CID number. Granted, the equipment is not designed for single use operation, but rather reading the CID of SD media in bulk quantity. Here is a screenshot of Nexcopy’s software reading 20 CID numbers:
I didn’t contact Nexcopy Incorporated for pricing of the equipment, but doing a quick search for the equipment shows me a price of about