BIOS LBA function

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teodori
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BIOS LBA function

Post 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.
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madanra
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Re: BIOS LBA function

Post 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.
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M2004
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Re: BIOS LBA function

Post by M2004 »

Another limiting factor is that your destination buffer should not cross 64kb memory
boundary.

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M2004
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teodori
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Re: BIOS LBA function

Post by teodori »

Ok thank you :)
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DavidCooper
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Re: BIOS LBA function

Post 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.]
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MSB-OS: http://www.magicschoolbook.com/computing/os-project - direct machine code programming
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