Ticket #9302 (new defect)

Opened 3 years ago

Last modified 3 years ago

FreeDOS - uide (CD-ROM support) problems

Reported by: fritz.mueller Owned by:
Priority: major Component: other
Version: VirtualBox 4.1.0 Keywords:
Cc: Guest type: other
Host type: other


Referring to Virtual Box error message #9191:

As already mentioned in the message 9191, uide.sys, a driver in FreeDOS, which supports SATA HDs and CD-ROMs (=replacement for oakcdrom.sys in older Win9x systems) has the problem, that it "hangs" for in about 2 minutes and then exits with the message:

EDD BIOS data ERROR, Disk 80h.

It works fine from a real boot disk in a real machine - and it works fine from vmware.

I talked with the programmer of uide.sys, Jack Ellis and got the following response: There seem to be 2 problems: First, they do not provide "EDD BIOS" data, which tells me the I-O device addresses for each hard disk. I need those addresses to "match" with the controller I-O addresses found during UIDE's PCI scan. Second, they appear not to support an "Identify ATA Device" command,

which UIDE issues to validate a disk's UltraDMA settings, etc.

If UIDE gets no reply to that command, it will "time out" after a long time.

You can check this bug report with one of my prepared small ISO images fdosboot_106.iso or fdosatwork_106.iso which can be downloaded from my website: or (both are in about 1,5 MB in size). Please note that uide.sys requires 80 MB RAM without any set options, so the RAM settings of virtual box for DOS should be at least at 96 MB!!!

A second thing I noticed with FreeDOS and virtual box: When you boot one of these ISO images and try to create a virtual HD with fdisk you have to run fdisk twice (instead of one time as usual). After the first time it reports an error message. First fdisk and then fdisk /mbr as fdisk seems to be not able to write the MBR at the first execution.


Change History

comment:1 Changed 3 years ago by kumba

I am running into a similar problem as well, however, after the 2 or so minutes, it detects the CD and HDD. The solution seems tied to having VT-x/AMD-V support enabled. See Ticket #9422 about NetWare 6.5 SP8 install going belly-up with VT-x, so it seems like VBox has some issues with its DOS emulation & VT-x that's affecting a few different things.

Note, I am testing FreeDOS 1.1-tst3 that includes fixes for VBox, so this may be somewhat addressed on the FreeDOS side already.

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