China DOS Union

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1. FindCD

■ Identify the drive where the CD-ROM containing the disc is located correctly in a multi-CD drive environment by defining a tag file.
■ Skip drives without a disc installed, avoiding the classic "Retry, Abort, Fail" error.
■ In MS-DOS 7.1 environment, automatically set the CDROM environment variable.
■ Determine the CD-ROM drive letter through the program return code.
■ Example:

FindCD boot\myutil.tag - Find and return the drive letter of the CD-ROM containing the specified file

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2. mkramdsk

Solve the 1GB problem encountered when creating a Win98 CD boot disk. Due to aging, Win98 cannot stably run on some machines with memory exceeding 512MB. For machines with physical memory exceeding 1GB, it cannot run normally on most hardware, often resulting in errors such as mode errors, out-of-memory reports, and boot failures, etc. (For details, you can google: windows98 memory 1GB).

On the other hand, Win98 startup usually requires using xmsdsk to create a virtual system disk. mkramdisk first detects the total physical memory and free XMS memory in the current computer, and then calls the xmsdsk tool to allocate the ramdisk. Features include:

■ Reserve only 256MB of physical memory for Win98, and use the remaining memory as ramdisk.
■ The minimum size of the ramdisk is 36864 KB, allocated from the high address, and the drive letter is z:.
■ xmsdsk must be in the working path or the path.
■ Since it was designed only to solve its own problem, no configurable command-line parameters are defined.
■ Since modern machines generally have large memory, it is recommended to put the Win98 memory swap file on the ramdisk to enhance performance (which is equivalent to indirectly helping 98 use large memory, heh heh)

[ Last edited by llm on 2006-4-28 at 15:35 ]

Originally posted by asbai at 2006-4-18 02:27:
■ Only reserve 256MB physical memory for Win98, and use the remaining memory as a ramdisk

Win98 supports a maximum of 768MB physical memory, and it's not excessive to allocate 512M memory for Win98 to use.

CD-ROM version of Win98, it is recommended to change the approach. Instead of using XMSDsk's RAM disk, use GRUB's RAM disk. First, create a hard disk image of Win98 (this image can be compressed with gzip), then use GRUB's map --mem command to simulate this image as a RAM disk hard disk for booting. Such a RAM disk directly becomes the C: drive, and the original hard disk will become the second hard disk.

Originally posted by JonePeng at 2006-4-20 23:52:
Windows 98 supports a maximum of 768MB of physical memory, and it's not excessive to allocate 512M of memory for Windows 98 to use.

This is hard to say. Theoretically, it can reach 1G, but in some hardware configurations, there may be problems even with 512M. Also, since it's originally for emergency booting, usually not much memory is needed, so the most conservative estimation method is adopted.

Originally posted by fujianabc at 2006-4-21 12:00:
For the CD version of Win98, it is recommended to change the approach. Instead of using xmsdsk's ramdisk, use GRUB's ramdisk.
First, create a hard disk image of Win98 (this image can be compressed with gzip), and then use GRUB's map --mem command...

I have tried GRUB's CD boot version before and never succeeded, sweat...

Whether it is virtualized as drive C or Z is not a very serious issue, and the compression ratio of gz is far less than that of the solid mode RAR. The DOS version of Unrar is also free/opensource.

BTW: GRUB 2 has been developed for a while since GNU took over. We can try it when version 2 comes out ^_^

[ Last edited by asbai on 2006-4-23 at 05:35 ]

Originally posted by asbai at 2006-4-23 05:32 AM:


I've tried the CD boot version of grub before and never succeeded, sweat...

Whether it's virtualized as drive C or Z doesn't seem to be a serious problem, and the compression ratio of gz is far smaller than that of the solid mode RAR. The DOS version...

The RAR under DOS does have a larger compression ratio than gz, but the time to decompress a compressed package is much longer than that of gz. There are hundreds of files to be decompressed in RAR, while gz only needs to decompress one img file under grub.

Grub 2, I don't know when it will really be usable. The functions added compared to the current grub 0.9x are many but not practical.

98 is not a problem, the key is the drivers. 98 is a large operating system, not like DOS where just a few drivers are enough. How to install the drivers for the mainboard, graphics card, sound card, and network card?

Originally posted by 272922032 at 2006-4-23 22:28:
Windows 98 is not a problem. The key is drivers. Windows 98 is a large operating system. Unlike DOS, which only requires a few drivers. How to install drivers for the motherboard, graphics card, sound card, and network card?

That's right. Generally, the system booted from the CD is used for emergency recovery. Many drivers just need to work, not requiring high performance. For example, the graphics card working in VGA or VESA-compatible SVGA is generally sufficient. The hard drive and CD-ROM can be used in DOS-compatible mode. Also, some drivers are not needed at all, like the sound card driver. It seems that no one boots a complete daily system from the CD, heh heh

Originally posted by fujianabc at 2006-4-23 11:53:

The RAR under DOS does have a larger compression ratio than GZ, but the time to decompress a compressed package is much longer than that of GZ. There are hundreds of files to be decompressed in RAR, while GZ only decompresses an IMG file under GRUB.

GRUB 2, wait to delete...

Well, GZ is indeed much faster than RAR, but a MINI98 itself is not very large, generally less than 30MB after extraction. And for a compressed package of a comparable size, whether there are 1 file or 10 files inside generally has little impact on the speed, except in extreme cases, such as having ten million files inside... That's a stress test on the file system ^_^.

Moreover, directly using the IMG virtual file system is not feasible for 98. When 98 starts, it must be on a non-read-only media. I haven't seen a boot loader that supports writing to IMG. Win32 started supporting booting from read-only media from XP onwards (WinPE).

Do you have any good articles on using GRUB for CD booting? I always have problems following the official documentation, which is frustrating.

I just hope to find a Windows series disc - based system that can run ordinary software. It doesn't matter what the kernel is. If there are no drivers, why do I want it? Using a disc - based system to chat on QQ online is my dream

Originally posted by asbai at 2006-4-24 12:14 AM:


Well, gz is indeed much faster than rar, but a MINI98 itself is not very large, generally less than 30MB after decompression. And for a compressed package of相当 size, whether there are 1 file or 10 files inside generally affects...

The img I made to boot Win98 is done by using the grub map --mem command to map the img file as a ramdisk, and the ramdisk is readable and writable, so there is naturally no problem of read-only.

As for grub for CD boot, I haven't seen any very good articles, many are relying on their own usual exploration.

Actually, the Windows 98 on the CD doesn't need to be compressed. The 700M CD space is enough. I can still collect many software and drivers. The key is the network card and graphics card drivers. And the motherboard drivers are also recommended to install. If these drivers are missing, Windows 98 doesn't have much use value. If it's just for file management, WINPE is enough. Why do I still need Windows 98?

[ Last edited by 272922032 on 2006-4-24 at 12:38 ]

Originally posted by 272922032 at 2006-4-24 12:35 PM:
Actually, it doesn't matter whether the CD-ROM version of Windows 98 is compressed or not. The 700M CD space is enough, and you can collect many software and drivers. The key is the network card and graphics card drivers, and the motherboard drivers are also recommended to be installed...

After compression, the boot can be a bit faster.
In terms of practicality, the CD-ROM version of Windows 98 was a hot topic before the emergence of WinPE. After the appearance of WinPE, the CD-ROM version of 98 is indeed not of much significance.

Wenjiu Bar is better than WenPE, this is a fact!

Originally posted by 272922032 at 2006-4-24 09:06 PM:
Wengjiu Bar is better than WengPE, this is a fact!

Why do you say so? In what specific aspects is it reflected?