China DOS Union

I run my finished 1.44M boot disk IMG in a VMWARE virtual machine. If I boot directly from the floppy image into MS-DOS7.1, then use MEM to check memory, the total conventional memory size is 640K. But if I add the image into an ISO made with EASYBOOT, boot from the CD, and then use MEM to check memory after loading the same IMG file, the total conventional memory size becomes 618K.
Also, I checked it with several of the latest antivirus programs, and there is absolutely no virus!!! Does anyone know why this happens

The reason is quite obvious. Although on the surface both are using an IMG file and both are emulation, the essence of the emulation is very different.

VMWARE, VirtualPC, QEMU and that kind are full-system emulators. Although you give them the IMG file, they simulate the IMG file as a floppy disk, just like a real floppy disk.

Another kind of emulation is partial emulation. It only emulates the BIOS interface and does not emulate the rest. This kind of emulation needs to allocate a certain amount of conventional memory space to store the emulation code, generally several KB, for example memdisk is 2K and grub4dos is 3K. The mem command recognizes that the code space used for emulation exists as an extension to the system BIOS, so when it reports memory, it has already removed this portion from conventional memory.

Partial emulation only takes up this tiny bit of memory space, while real emulators like VMWARE, VirtualPC, and QEMU are all extremely huge. Although they create an environment very close to a real one for the user, their complexity is very high, the difficulty of emulation is very high, and the CPU and memory resources they consume are also very large. It is absolutely not something that can be done with just a few K.

So does that mean if it's burned to a CD and the IMG file is booted from the CD on a real computer, then the situation of conventional memory being occupied will not occur?

As long as it is made properly, of course that is the case. For example, the win98se CD boots by emulating a 1.44M floppy disk. This emulation is done by the BIOS, so it does not occupy the user's conventional memory.

Among these programs, easyboot, Boot Scriptor, bcdw, diskmenu, grub, which one has better compatibility for making boot CDs

The programs you mentioned all serve different purposes, so how can they be compared? Some are CD creation tools, some are boot management tools, so they are not comparable.

If you make it in the win98 CD format, there should be no compatibility problem. That is, booting by emulating a 1.44M floppy disk. This is a most basic CD standard. As for others, such as CDs made using hard disk emulation mode, or using “no emulation mode,” they are compatible with newer machines, but on very old machines they may fail to boot.

Sure enough, an expert really does know this much. I've been using DOS since 1996, and after using DOS for so many years, I feel ashamed of my inferiority!!!!!!!!
Then which one can make a standard WIN98-format CD, EASYBOOT? DISKMEU, which one
And one more question I'd like to ask: under DOS, when using DEL or an external command, how can I delete all files in the current directory or some directory without a prompt? For example, if I use the internal command DEL and enter ＂DEL ．＂ at the DOS prompt, it asks whether to delete all files and gives a Y or N choice. How can I stop it from showing that choice? Or what tool can do it (other than using echo y|del *.* )

No need to be so polite. I only know a little myself, and am just showing off my poor knowledge. I'm afraid there may still be many mistakes, so I hope the brothers and sisters here won't hesitate to correct me.

What we call the so-called standard win98 format here is actually the boot mode of emulating a 1.44M floppy disk. As long as a CD creation method supports this mode, it can make a bootable CD just like win98 with the best compatibility.

Any CD creation software can make this kind of format, because this format is too basic and too universal. What you need to study is how to use those programs to achieve this. Just read the software instructions or help and learn how to use them.

If the software accepts a 1.44M file as a boot file, then a CD made this way is in this emulation mode. Generally you can find it in the menu. It seems you haven't mentioned many tools. Actually I have used winISO, and there are many others like it, but they are all more or less the same, and all can do it.

DOS command line (its shell is command.com) is rather weak in functionality. It's enough if it can be used somehow; there's no need to take it too seriously.

One last favor I'd like to ask of you, expert: where can I find a Chinese command tutorial or instructions for CD SHELL (a better boot disk creation tool than DISKEMU)? I want to know how it can support Chinese, and how some commands are used! This question is rather difficult, so if there isn't any that's fine too! Thanks. My QQ7840433

diskemu and cdshell are both very nice tools and very familiar-sounding, but I still haven't had time to get in touch with them, sorry.