Install virtual floppy drive.
Mount.
Use this drive in DOSBox.

I think I'm starting to better understand the nature of the problem. The Infocom booters do not have a filesystem _at all_...it isn't FAT or anything else, it's entirely custom.

I've mounted a raw 160KB Infocom disk image under ImDisk, which Windows of course immediately wants to format (and I declined 😉.

If I MOUNT it under DOSBox as drive A (-t floppy), it again gives the impression of mounting OK, but attempts to run ZorkTools against it results in:

---

Insert Infocom game disk in drive A.

press any key to continue....

undefined error occurred
while reading drive A
track 1 sectors 1 - 8
disk operation aborted.

---

Is there any way to get DOSBox - through native or external means - to see "floppies" without a FAT filesystem and be able to interact with them on a sector basis? (I imagine this is common to many disk protection mechanisms of the era.)

Rodney

DOSBox wants a recognizable filesystem on IMGMOUNTed floppy images when they're mounted. Perhaps if you boot real DOS it won't complain about no filesystem until you try to read the disk with some command.

ripsaw8080 wrote:

DOSBox wants a recognizable filesystem on IMGMOUNTed floppy images when they're mounted. Perhaps if you boot real DOS it won't complain about no filesystem until you try to read the disk with some command.

I think you're on to something! Using this method (with FreeDOS), I get:

Using partition 0 on drive; skipping 63 sectors
Mounted FAT volume is FAT16 with 64439 clusters

in the console after BOOTing a 2GB FreeDOS image on C and having IMGMOUNTed a 160KB floppy image on A, and

Unable to find the code which sets
the top of memory address for the game.
This disk is probably not an INFOCOM
game. IVD aborting...

from ZorkTools. I consider this a major step forward because I'm getting precisely the same error above when trying this from VirtualBox, which I've been made to understand _should_ work.

I'll keep digging at it - thank you for the tip!

Rodney

It looks like the root cause of the issue is that the original Infocom booters deliberately malign the first 8 sectors into 4 1024-byte sectors, and use the bootloader to reprogram the FDC to deal with this at load time. I doubt ZorkTools will ever work properly outside of actual hardware. Thanks to all who contributed!

Rodney

rhester72 wrote:

I doubt ZorkTools will ever work properly outside of actual hardware.

In DOSBox, you are surely correct.

In other emulators... Sure it will work (if not now then at some point), you'll just have to test it under actual PC emulators like PCem or MESS instead of DOSBox. But... as this is the support forum for DOSBox, can't really discuss that more here in this subforum. But try "PC Emulation" here in "Eddie the Shipboard Computer", or MESS's forum elsewhere. 😀