Firmware is the software on the hardware, basically. If you take a hard disk and look underneath it, there is a PCB with chips on it. The firmware lives in ther

Firmware is the software on the hardware, basically. If you take a hard disk and look underneath it, there is a PCB with chips on it. The firmware lives in there and is responsible for doing the job of reading/writing data to the disk in a specific format. If you take the platters out of one hard disk and put it into another hard disk with different firmware, the other hard disk PCB won't be able to read it or write to it. I found this out by having a dead Hitachi drive (yes, the IBM "Deathstar" disks after they were sold to Hitachi) so I bought another identical drive and swapped PCBs but on startup the read/write head would not settle as there was a mismatch between the PCB firmware number and the firmware identifier written on the start of the disk. So, although I thought they were identical disks they were not.