The so-called "CD image" is actually a file. You can use special burning software (combined with writable CD-ROM drive) to burn image files to CD-ROM.
There are several formats for CD-ROM image. At present, the most common format is the format with the extension "ISO" (this extension comes from ISO 9660 standard). Most CD image files provided by the operating system are in ISO format.
What is a bootable CD image?
Boot CD is also called boot CD. After this CD-ROM is inserted into the CD-ROM drive, if "CD-ROM drive priority startup" is set in the BIOS, you can start the computer with this CD-ROM.
Similarly, there are two types of CD images: bootable and bootable. For example, some ISO for storing video/music is not bootable; The image used to install the system must be bootable (obviously). So you have to make a bootable USB flash drive, provided that the CD image you use is bootable.
◇ How to judge whether the CD image can be started?
Just said: the CD image is just a file, not a physical CD. So it can't be plugged into a physical CD-ROM drive, and it's inconvenient to test with a virtual CD-ROM drive. I suggest testing with virtual machine software. Students who have never heard of "virtual machine software" can take a look at the previous tutorial "Literacy Operating System Virtual Machine".
The test method is as follows: First, build an empty virtual system (Guest).
OS), set the image file you want to test in the "optical drive" of the virtual system, and then start the virtual system. If you can see the relevant screen of the operating system, it means that the startup is successful; If the screen turns black or appears
The English prompt of the system cannot be found, indicating that this image cannot be started (can be started).
◇ mixed mode
For bootable optical discs, there is a mode called "Hybrid mode". This mode of CD can be directly burned into a physical CD or directly made into a bootable USB flash drive.
Nowadays, more and more operating system installation CDs adopt "mixed mode", which is convenient for everyone to make "bootable U disk". In addition, although some optical discs are not in "mixed mode", they can be converted into "mixed mode" by tools.
★ What is the general production method?
The so-called "general rule" is that this method has nothing to do with the built-in system of optical disks, and is suitable for most optical disk images (Windows system disks, Linux system disks, and Apple system disks).
However, "universal law" does not mean "universal law". Some ancient systems (such as Win2000 and WinXP) may not be solved by the following methods. For this old system, you need to use special tools (considering that the old system is used less and less, I won't say it for the time being).
The three tools introduced today should be able to do this:
Installation disk after 1 WIndows Vista (Win7、Win8)
2. Various mainstream Linux distributions (such as Debian, Ubuntu, RedHat, CentOS, Fedora, etc. )
★ Why choose these tools?
There are many tools that can achieve the purpose of "universal". I chose three open source models today.
Let me introduce you. Why only choose open source? There are the following points:
First of all, I prefer open source software (purely personal preference)
Secondly, open source software is not only free, but also does not need a registration code, and there is no time limit (convenience).
Third, compared with closed source software, open source is more reassuring (safe).
Students who often read my blog should know that I am more concerned about "safety", so I add the third point.
The main purpose of making bootable U disk with CD image is to install the system. If the production tools used are unreliable (for example, using Trojan horse), the startup USB flash drive you made is unsafe, which will lead to the unsafe system you installed.
By the way, why don't I like to use the WinPE disk tool?
The first is the limitation of PE mode-it can only be used under Windows system (and now more and more netizens are playing Linux or Mac OS).
Secondly, many PE tools are made in China, and some domestic PE tools like to "carry private goods". Don't blame me for "worshipping foreign things and obsessing foreign things". There are too many hooligans in domestic software, which is not practical to use.
★rufus's gameplay (Windows platform)
Rufus, a tool, is not well-known, but it is very cool to use (there are many customization options in the interface, and it is fast). Its official website is here.
"。
Reminder: rufus' exe file has a digital signature. After downloading, verify whether the digital signature is valid (form this good habit). For those students who don't know how to verify digital signatures, please see "Checking the integrity of reading and writing files-about hash values and digital signatures"
》
The screenshot of the interface of this thing is as follows:
It will format the USB flash drive before burning, so be sure to check "quick format".
. If this item is not selected, it will be "fully formatted". The current USB flash drives are several GB, and it takes a long time to fully format them.
★ How to play ★UNetbootin (cross-platform)
The official website of UNetbootin is here.
"。 At the beginning of the homepage are download links for three platforms (Windows, Linux, Mac OS X).
The screenshot of the Windows interface is as follows:
The use of this thing is very simple, you should understand it by looking at the label on my screenshot.
★dd gameplay (cross-platform)
Dd is a very useful Linux/Unix.
Command, which can be used for "naked reading and writing" between devices. The so-called "naked reading and writing" means ignoring the file system and directly reading and writing physical devices across the file system. So it can do a lot of "copy life"
One thing that copy/cp can't do is to burn the CD image to a USB flash drive.
Play on Linux/Unix
Suppose you have an iso image file with the path ~/xxx.iso.
Suppose the device corresponding to your USB flash drive is /dev/sdb.
You can then use the dd command, as shown below.
dd bs=4M if=~/xxx.iso of=/dev/sdb
Explain a little:
Parameter bs=4M means to read and write 4MB bytes of data in a batch (I usually use 4M, but you can also use 8M, 2M or 1M).
The if parameter indicates the path of the input (file/device), in which a CD image file is used.
The of parameter indicates the output path (file/device), and the U disk device is used here.
Most Linux distributions have this command built in, so in general, you can use the dd command without installing additional software packages. After the dd command is executed, remember to execute the sync command to synchronize the disk cache, and then pull out the USB flash drive.
How to play on Windows?
Dd command is also ported to Windows system. See "Here" for details.
"Download. The page is very long, and the first half is help. You can find the download link by looking for "Download for dd".
I am currently using version 0.5 (0.6 or beta, not very good).
The usage of dd under Windows is similar to that under Linux. The only thing to note is the "device path" of the USB flash drive.
(Usually there is only one partition on the USB flash drive) After inserting the USB flash drive, if the drive letter is F: then the corresponding device path is \ \. \f:
If your iso image file is in C:\xxx.iso, use the following dd command to burn the image to a USB flash drive.
dd bs=4M if=C:\xxx.iso of=\\。 \f:
(The parameters have been explained just now, so I won't repeat them here. )
★ Comparison of advantages and disadvantages
Summarize the advantages and disadvantages of the above three methods.
Compatibility aspect
Rufus and UNetbootin hit it off better than dd. The disadvantage of dd is that if the image itself is not mixed,
Mode (mixed interpretation, mentioned at the beginning of this article), after burning with dd, will not start. And Rufus and Uttar pudding.
You can do the corresponding processing when burning a USB flash drive.
In view of this shortcoming of dd, there is a remedy:
For Linux/Unix platform, firstly, use the isohybrid command to convert the iso image into mixed mode (this command belongs to the SysLinux/ISOLinux software package.
)。 Assuming that your CD-ROM image is located in ~/xxx.iso, use the following command to convert it: (Unfortunately, there is no windows version of this command).
isohybrid ~/xxx.iso
As for the comparison between rufus and UNetbootin, I personally think that rufus is not only better than UNetbootin, but also better than some other tools (such as
Universal USB installer). I have encountered: the same ISO image, the same physical USB flash drive, which can't be started after being burned with UNetbootin, and
Rufus can be started after combustion.
As far as speed is concerned
Dd is the fastest (as mentioned earlier, dd is "naked reading and writing", so it is fast). Rufus is faster than UNetbootin (Rufus official website interface has the speed comparison of several different tools).
Ease of use
UNetbootin and rufus are very similar-both have stupid graphical interfaces.
Dd is the least easy to use-you have to use the command line.
Cross-platform
UNetbootin is better than dd and rufus (rufus is only available in Windows).
Just a reminder:
The "cross-platform" here refers to the tool itself, not the CD produced. For example, although rufus only has Windows version, rufus can make Linux installation disks.
★ Feedback Although I have tossed some systems, the contact surface is still very limited. In addition, making a bootable USB flash drive depends on many factors (including: BIOS model of computer, brand of USB flash drive, type of CD and luck). So you are very welcome to give feedback on the content of this article (which can supplement your experience or problems you have encountered).