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Create CHD with FreeDOS inside. #116984 03/03/20 03:11 PM
Joined: Feb 2020
Posts: 3
Carlo Bra Offline OP
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Joined: Feb 2020
Posts: 3
I would like to create a CHD file with an installation of FreeDOS inside, to be used with the PC/XT/AT machine emulated by MAME.
Unfortunately, I'm a bit lost and although I read the documentation, I have still no idea how to do it.
Have you some suggestions for doing it, or do you know if there are already available images to be downloaded?

Thank you very much.

Re: Create CHD with FreeDOS inside. [Re: Carlo Bra] #116985 03/03/20 09:00 PM
Joined: Jan 2012
Posts: 1,064
rfka01 Offline
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Joined: Jan 2012
Posts: 1,064
Hi Carlo,

get Freedos from (use the boot floppy from FD12FLOPPY.ZIP, unpack the floppy image.
This installer expects you to download the CD image as well for a full install, but you can use just the boot floppy for a basic install.

Then open a command line window and move to your MAME directory.

Create a CHD file with

chdman createhd -c none -o 820-6-17_harddisk.chd -chs 820,6,17 

I've used the track/head/sector values from a Seagate ST 251. You should see CHDMAN create the harddisk file.

Open MAME with the ct486 driver. This is handy as its BIOS can autotype the harddisk, and you can assign a nice amount of RAM:

mess64 ct486 -window -ramsize 16M

TAB into MAME's file manager and attach the FreeDOS floppy image to the first floppy drive and the harddisk image to the harddisk slot. RESET!!!

On the next boot, enter the emulated PC's BIOS, choose "Auto detect hard disk", your CHD file should be picked up, the second harddisk should be empty.
Then enter the standard CMOS settings, set both floppy drives for 1.44MB, exit to the main BIOS menu and enter Advanced CMOS settings.

Set "System boot up sequence" to "A:, C:"

Exit to the main BIOS menu, select "Write to CMOS and exit" and reboot the emulated computer.

It will boot from the Freedos disk - ignore the error message, your harddisk image is completely blank.

Select your preferred language, then exit the installer to DOS. Issue "FDISK"

Depending on the size of your disk, select FAT32 support, create a DOS primary partition, set it active and exit FDISK, then REBOOT!!!

The disk will take you through the language selection again, exit the installer, then issue "FORMAT C: /S" and confirm with "YES".

After formatting the hard disk image, issue "MD C:\DOS" and "COPY FDSETUP\BIN\*.* C:\DOS"

This will copy a base system onto your harddisk.

TAB into MAME's menu, select file manager and empty the Floppy slot. Reboot, and FreeDOS starts from harddisk.

This should get you going.

Last edited by R. Belmont; 03/03/20 09:15 PM. Reason: Added "-c none" to CHDMAN command line lest disaster result.

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