I think this counts as a hardware issue, I've got 4mb of RAM but the RAM counter at POST only goes up to 3,968kb. I'm guessing that I've got the BIOS being shadowed in RAM, which I think is done because accessing RAM is faster than accessing the BIOS.

My question though, is how much is the BIOS accessed once DOS is loaded? Are there meaningful benefits to this? As I delve in to the wonderful world of the 640kb limit , High memory and EMS, I'm newly aware of how precious every kilobyte is, so don't really want to go throwing 128 of them away for no reason.