[SOLVED] Odd behavior with AH=0x03/INT=0x13

[Octocontrabass]

If you can see the ROM chip, you can check the part number to see how big it is. If it's a parallel ROM, you can count the pins to figure out the maximum possible size.

You can check SMBIOS, but there's no guarantee it'll be accurate, since nothing important would break if it's wrong.

Some BIOS ROMs have an internal filesystem that can help you figure out the ROM size, but most of them are undocumented.

It's usually pretty easy to guess the ROM size if you read way more than necessary and then examine the results with a hex editor. This can be difficult on newer PCs as ROMs keep getting bigger.