Boot Manager: floppy to USB(Plop) -> Missing operating system?

[nmjk]

I have two separate laptops from which I'm trying to recover data. Both are x86.

Laptop 1
Running a scaled down Ubuntu default installation, / and /home are on the same partition. Need to recover deleted files from /home and so had to be able to access / as readonly. I successfully created a USB bootable Plop Linux installation, and that worked perfectly! I've now started the file recovery process.

Laptop 2
Fueled by feelings of success and having a bootable USB drive I decided to tackle an old (c.2000) laptop with a corrupted operating system and no ability to boot from optical or USB. Luckily I found the Plop Boot Manager -- things are looking up! I can put this on a floppy and then bootstrap into the USB image that I've already used successfully elsewhere.

Except...
The boot floppy works. However, when I select USB it says "missing operating system" even though I know it's accessing the right USB device (the thumbdrive flashes). I've configured the floppy image to force USB 1.1, tried once each with 1.1-mode1 and 1.1-mode2, no success.

Given the era of the laptop, what is most likely the problem, and how can it be fixed? I know the USB image is fine, so I've concluded that the problem lies in the Boot Manager either: (1) finding/reading the USB device, or (2) finding the boot record on the USB device.

Assistance would be greatly appreciated!

[Elmar]

hi,

Given the era of the laptop, what is most likely the problem, and how can it be fixed? I know the USB image is fine, so I've concluded that the problem lies in the Boot Manager either: (1) finding/reading the USB device, or (2) finding the boot record on the USB device.

the message comes not from the boot manager. it comes from the program in the mbr of the usb drive. did you set the boot flag?

regards
elmar

[nmjk]

Yes, the boot flag is set in the MBR of the USB drive. As mentioned, laptop#1 boots from it with no trouble at all. Something about the configuration, whether hardware or software, is preventing laptop#2 from reading the MBR correctly.

[Elmar]

when you read the missing operating system message, then the mbr was loaded correct, if the mbr is not loaded correct and executed, then the system would hang without any message.

[nmjk]

Hrm. In that case, what would make the same MBR point successfully to the boot image on one computer, and unsuccessfully on the other?

[Elmar]

what usb drive do you use?
how big is it?
whats the partition id on the usb drive?
do you use the factory mbr?
what plop boot manager version do you use?