Is it on the latest BIOS? Also what drive model is it? It's great that you know it's working on another computer - I was going to say that the LS120 part might be damaged but you've ruled that out. They're pretty fragile so more than one of my LS120 drives can't read LS120 disks anymore but is fine with floppies. That's not your problem though 😀

The LS-120 even being supported as a floppy drive is pretty good, but maybe that support is limited. Maybe check whether there's any driver for win95/win98 to support LS120 too, I can't remember if that's needed or not.

Since it works in another environment, it seems like a limitation of the BIOS support.
There is a DOS driver for these drives, it worked for me on a 486 which didn't have any BIOS support for these drives. Maybe it would also fix your issue with 120MB disks.
This file also includes a Win95 driver which I don't think I've ever tried.

Are you using original Win98 or Win98 SE? I think 98SE has a built in driver for LS120 (in the GUI only - not at a command line boot). So if it's not working in the GUI of 98SE, then I don't think lack of driver would be the reason.
I don't know about original Win98, but it might also have a driver built in.

Another possibility is power supply voltage. The drive might not work correctly if the 5V or 12V supply isn't up to spec, and this might be seen as a failure on the 120MB side of operation.

Thermalwrong wrote on 2023-10-02, 20:06:

Is it on the latest BIOS? Also what drive model is it? It's great that you know it's working on another computer - I was going to say that the LS120 part might be damaged but you've ruled that out. They're pretty fragile so more than one of my LS120 drives can't read LS120 disks anymore but is fine with floppies. That's not your problem though 😀

The LS-120 even being supported as a floppy drive is pretty good, but maybe that support is limited. Maybe check whether there's any driver for win95/win98 to support LS120 too, I can't remember if that's needed or not.

Hi! This is LKM-F434-1 Matsushita. BIOS of 1020+ is Award 4.51PG ver. 1.36

shamino wrote on 2023-10-03, 03:29:

Since it works in another environment, it seems like a limitation of the BIOS support. There is a DOS driver for these drives, i […]
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Since it works in another environment, it seems like a limitation of the BIOS support.
There is a DOS driver for these drives, it worked for me on a 486 which didn't have any BIOS support for these drives. Maybe it would also fix your issue with 120MB disks.
This file also includes a Win95 driver which I don't think I've ever tried.

Are you using original Win98 or Win98 SE? I think 98SE has a built in driver for LS120 (in the GUI only - not at a command line boot). So if it's not working in the GUI of 98SE, then I don't think lack of driver would be the reason.
I don't know about original Win98, but it might also have a driver built in.

Another possibility is power supply voltage. The drive might not work correctly if the 5V or 12V supply isn't up to spec, and this might be seen as a failure on the 120MB side of operation.

This BIOS limitation is something that is on my mind also but you know - BIOS is showing this correctly. In Windows 98SE on another computer it works perfectly, on that ATC in Windows 98SE (original) it's visible booth in device manager and in my computer but can't access 120MB disks.
Similar case under DOS and Windows 95 (of course after driver installation).

Voltage is 5.04 and 12.29 so looks good from that perspective also.