China DOS Union

Due to differences of opinion between author Jack R. Ellis and some people from FreeDOS, XDMA/XCDROM has stopped being updated. Please switch to QDMA/QCDROM. The certification has been changed from GPL to Freeware.

http://johnson.tmfc.net/freedos

No translation needed as the text is in English.

Not very clear about what controversy happened. However, it's a pity that neither the source code nor the stripped-down version is available now. But it still seems that it doesn't support starting with Win3.x.

I don't know when it will support booting Win3.x. Now, if QDMA is loaded and then Win3.2 is started, it will prompt a file error during startup and cannot be launched.

In addition, this QDMA also has a very big use (although it hasn't reached perfection). The DOS driver version 5.0 of the SB Live! sound card for some reason, after loading the sound card driver, as long as the program is using the sound card, it cannot read and write the hard disk normally. For example, the Chinese Paladin cannot run normally. But after loading QDMA, this problem is solved. However, QDMA only supports IDE hard disks and does not support SATA hard disks, so this solution is only effective for IDE hard disks and not for SATA hard disks (I have two hard disks, the small one is IDE and the large one is SATA). I wonder if QDMA can also provide support for SATA hard disks (at least simulated support), so that these programs using the sound card can also read and write the hard disk normally when using the sound card on the SATA hard disk?

Then what about UDMA? What are the advantages and disadvantages of the two?

In terms of measurement, purpose, and function, the volume is already very small (just a few kilobytes), so there is no simplified version attached.

UDMA has many bugs. XDMA is reprogrammed, and there are fewer problems. QDMA adds programs to cooperate with QCDROM (CD-ROM UltraDMA), which can be said to be almost complete.

Of course, we still need to test more to know if there are any hidden problems. I can't test it myself...

Originally posted by Wengier at 2006-4-28 11:59 PM:
I don't know when it can support booting Win3.x? Now if QDMA is loaded and then Win3.2 is started, it will prompt a file error and cannot be started.

Jack hasn't used Win3.1, so he hasn't specifically accommodated it. It's very stable running under DOS.

In addition, Win3.1 has its own Virtual Disk Driver, which should have conflicts with any disk driver. Back then, HyperDisk even needed to be specially updated to avoid the problems of Win3.1.

Then it is suggested that Jack add a function, that is, when it is found that Win3.x is starting, it will automatically block itself. This is estimated to solve the problem of Win3.x and should be quite useful.

I think he didn't expect there are still people using Win3.1.

He has very strict requirements on file size and won't randomly add functions unless they are necessary functions.

If I think about it, solving the compatibility issues with Windows should also be considered a "necessary" fix, and it shouldn't add too much code. After all, Win3.x is one of the best GUI interfaces under DOS, and it would be a pity if it couldn't be used.

Probably because VPC cannot use DMA, the test found that QCDROM is very slow (this is for reading files from the CD-ROM), much slower than VIDE-CDD. I'm afraid that even in real machine testing, under the premise of being able to load DMA, its speed can only reach the level of VIDE-CDD. Disappointed!

Can't help but test on the actual machine, and the result is more disappointing. UDMA can be loaded successfully, but Qdma says "disk is not UltraDMA".

Originally posted by zhangxue at 2006-4-30 05:57 PM:
It may be because VPC cannot use DMA, and the test found that QCDROM is very slow (this is for reading files from the CD-ROM), much slower than vide-cdd. I am afraid that even in the actual machine test, under the premise that DMA can be loaded, ...

You mean Virtual PC?
Have you executed QHIMEM and QDMA?
Without cooperating with QDMA, no matter how fast QCDROM reads, writing to the hard disk cannot be full speed.

Originally posted by zhangxue at 2006-4-30 07:23 PM:
Couldn't help testing on the actual machine, and the result was even more disappointing. UDMA can be successfully loaded, but QDMA says "disk is not UltraDMA".

QDMA is not allowed because it is "more strict" in checking, and no one can save the data if it is damaged.

UDMA is a very "early" work, with many bugs, so use it with caution.