What you're missing out here Mnem is that this isn't stock hardware running stock Windows. This is a bit of embedded gear. Having watched EEs who believe themselves to be
genius* programmers in action it is entirely possible that the muppet in question
may have relied on knowing the exact physical disk layout in use to have done something like hide the enabled options in a specific disk sector, called out by a
"magic number" hardcoded into the code, which he them proceeds to read directly from the disk with a BIOS call. (If done, the options sector will of course be cleverly encrypted by XORing each byte with the number '42'.**) Or may have created a backing buffer for memory at a known, again hard coded with magic numbers, location on disk that is read and written directly, bypassing the operating system entirely.
Faced with the possibility of this level of
"coding brilliance" being present it's wise for embedded gear to produce a 1:1, sector by sector clone.
The aim here isn't to get a perfectly optimised, or even partially optimised, disk system. It's to get a
working disk system that will be more reliable than the ageing drive that's currently there and, with a little bit of luck, may even be faster. The later is "nice to have" but isn't part of the objective and is easily lived without.
*The word "genius" here is to be pronounced exactly as it was by Phillip Pope playing "Leonardo Acropolis" in the Blackadder II episode "Money" as he declaimed "I am
genius".
**True story, I've seen this done as 'encryption' in an option encoding scheme.