Imgmount of 720k disk image and debug info \ VOGONS

Imgmount of 720k disk image and debug info

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First post, by erosselet

Posted on 2025-10-25, 17:26

erosselet Offline

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When I did "imgmount a disk1.img -t floppy", imgmount successfully mounts the img and I can do a dir of the A: drive. But if I launch debug and type "L 100 0 7 1" to explore the directory via Debug, nothing but zeroes appear when I type "D 100". Where is the directory information? I know the img is FAT12 but the information provided in Norton/Socha's Assembly Language book for the IBM PC doesn't line up with my DOSBox experience in this area. I figure Dosbox emulation of disk images is simply different from how MSDOS accesses physical disks. If so, is it even possible to build utilities like Dispatcher inside a Dosbox environment ?
Thanks,
Elliott Rosselet

Reply 1 of 5, by peterfirefly

Posted on 2025-10-25, 17:54

peterfirefly Offline

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It's not actually running DOS. It just pretends to.

Reply 2 of 5, by jmarsh

Posted on 2025-10-26, 01:26

jmarsh Offline

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If you want DOSBox to run real MSDOS you have to use the boot command to load a disk image.

Reply 3 of 5, by ripsaw8080

Posted on 2025-10-26, 05:34

ripsaw8080 Offline

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Reading sectors from disk images that way (INT 25h) works in DOSBox SVN.

Reply 4 of 5, by erosselet

Posted on 2025-10-27, 01:32

erosselet Offline

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I found that accessing the directory using Debug works OK when mounting the disk img file (drive 0) while booting freedos installed on c (drive 2). When starting Dosbox, can the Boot options specify a floppy image without booting from the floppy? The floppy is pretty ordinary i.e. not bootable. Anyway no urgency since I found a freedos solution. I'm just a lot more familiar with dosbox to do assembly language and Turbo C programming from the old days since my main goal is to learn how to build a compiler in C on my phone

Reply 5 of 5, by superfury

Posted on 2025-10-27, 07:37

superfury Offline

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Boot options that aren't used to boot? That'd be useless? You can use the autoexec section to setup some environment though. And all other sections to configure Dosbox itself of course.
The autoexec section of dosbox.conf (or equivalent) is simply executing the commands like autoexec.bat on a floppy/hdd/bootable cd-rom emulated floppy disk image.

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