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BIOS LBA function
Posted: Thu Oct 10, 2013 6:54 am
by teodori
Hello, for my bootloader I use the BIOS LBA read function and I want to know how many sector it can read? Is there a standard limit? It is defined with 2 bytes, so theoreticly I can load 0xffff (65535) sectors.
Re: BIOS LBA function
Posted: Thu Oct 10, 2013 7:47 am
by madanra
On
the wiki, it mentions some BIOSes have a limit of 127 sectors = 63.5KB. Ralph Brown's interrupt list mentions the same limit.
Re: BIOS LBA function
Posted: Thu Oct 10, 2013 8:00 am
by M2004
Another limiting factor is that your destination buffer should not cross 64kb memory
boundary.
Regards
M2004
Re: BIOS LBA function
Posted: Thu Oct 10, 2013 11:22 am
by teodori
Ok thank you
Re: BIOS LBA function
Posted: Thu Oct 10, 2013 1:40 pm
by DavidCooper
[If you ever need to write to disk using the BIOS and LBA, don't assume that it will be 127 sectors too. The machine I program on has a BIOS that can only handle 64 sectors when writing data, though 127 when reading.]