One of the major BIOS manufacturers had a limit of 0x7F (127d) sectors per transfer. Most other manufacturers followed suite.
To be 100% accurate, you need to do two things when using this function, not counting checking to see if it is available.
- Do not transfer more than 127 sectors at a time.
- Do not cross a 64k boundary with your buffer.
In other words, if you need to transfer more than 127 sectors, you need to call this function multiple times, as well as the buffer used must not have the read cross a 64k boundary.
Ben
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http://www.fysnet.net/osdesign_book_series.htm