Why wasn't I able to make a USB bootable?

[chrstrbrts]

Hi,

I posted the other day that I successfully booted my own code.

I didn't mention, though, that that successful attempt was my second that night.

I initially attempted to burn bootable code to a blank USB drive that I had.

I wrote my source code, used NASM to assemble it, and used dd to burn it to the first sector of that spare USB.

I then attempted to boot my code, but it failed on my laptop.

My laptop just booted Windows instead.

I thought that maybe my laptop which is fairly new had some UEFI stuff going on preventing my code from being booted.

So I tried to boot my code on my older desktop which is old to enough to have been shipped with Windows 7.

I don't think that my desktop has crazy UEFI security stuff going on.

But, my code failed again and did not boot.

I looked at my binary with a hex editor just to make sure that 0xaa55 was at the end, and it was.

I then burned my binary onto a different USB drive that I had.

This time it worked.

So, why did the first USB drive fail but the second worked?

 

[Tweak155]

First 2 thoughts are drive size and file system (I'm assuming both would be NTFS at this point, but you never know...).

Sometimes hardware doesn't like specific hardware though. When I had to update my Ford Explorer with a USB drive, I had the same problem... even though the drive I tried to use initially was the right size, for whatever reason my vehicle didn't like it. I finally tried a different USB drive and it worked.

 

[chrstrbrts]

First 2 thoughts are drive size and file system (I'm assuming both would be NTFS at this point, but you never know...).

Well, the drive that worked had an 8GB capacity (it is rather old). The drive that failed had a 16GB capacity. The file system after the burn for both is RAW, not NTFS or FAT. I did format both as FAT initially though.

Sometimes hardware doesn't like specific hardware though. When I had to update my Ford Explorer with a USB drive, I had the same problem... even though the drive I tried to use initially was the right size, for whatever reason my vehicle didn't like it. I finally tried a different USB drive and it worked.

You updated a car with a USB? Explain, sir.

 

[Tweak155]

You updated a car with a USB? Explain, sir.

The Sync system on Ford vehicles can be updated by downloading the update on a computer, formatting the USB and putting those update files on it. You then take it out to your car, stick it in while the system is on and it will trigger it to use the update on the pen drive. Pretty nifty, although the process takes a long time and you need to leave your car running.