Normal means CHS access (int13) is passed through to the disk, with the 504 MB limit for IDE disks due to the famous lowest maximum C/H/S definitions in IDE and int13
Large means CHS access goes through some arbitrary kind of conversion usually but not necessarily based on bit shifts goes on, this has various implementations (and so is not guaranteed compatible across PCs or, for that matter, int13 implementations such as if you switched to the XTIDE option rom), some break at around 2 GB, some can go all the way to 8 but are less compatible because of MS's 256 heads bug (there may be a "Large disk access mode = DOS or Other" option to limit them to 255 wasting some capacity, or a functional equivalent to this option may be always on)
LBA means CHS access is converted to a sector number and LBA(28) mode is used instead, this is generally the best option - if your disk supports LBA that is!
Of course, all of these stop at the int13 maximum of 1024/256/63 and none of this applies to "int13x", which is proper LBA passthrough...
...So, what's up with that Normal numbers if I said int13 is limited to 1024/256/63?
Well, something does really apply even to true LBA mode - the BIOS still needs to know the hardware-compatible CHS capacity for the "extended disk parameter table", but then who knows what it will declare in int13 for capacity - maybe 504MB (1024/16/63), maybe something invalid, who knows? 😁
(I keep a few disk detection utilities on my main DOS floppy to try to investigate...)
I have a 2011 computer, apparently designed in 2009, that works reasonably with most HDDs which only declare 1024/256/63 as their CHS capacity, but is broken for MS operating systems with CF cards that are designed to support CHS up to 127 GB!
Robin4 wrote on 2023-01-21, 18:10:
Only with the MR bios rom i could do over 64GB.. But havent tested it out yet.
Impossible - or rather, guaranteed not to allow int13 access over the 8 GB limit; might still be valuable if the original firmware has a lower maximum for LBA/Large or outright freezes with an oversize disk!