Floppy Disk Controller: Difference between revisions

This can be described in C with the following code:

 

void lba_2_chs(uint32_t lba, uint16_t* cyl, uint16_t* head, uint16_t* sector)

{

*sector = ((lba % (2 * FLOPPY_144_SECTORS_PER_TRACK)) % FLOPPY_144_SECTORS_PER_TRACK + 1);

}

 

You would then send this data to the floppy controller.

The basic set of floppy registers can be found in the following enumeration:

 

enum FloppyRegisters

{

CONFIGURATION_CONTROL_REGISTER = 0x3F7 // write-only

};

 

All commands, parameter information, result codes, and disk data transfers go through the FIFO port.

with a * and a comment.

 

enum FloppyCommands

{

SCAN_HIGH_OR_EQUAL = 29

};

 

==== "Deleted sectors" ====

The following code intentionally contains a common bug that causes an infinite loop (waiting for IRQ6) on most emulators.

 

volatile byte ReceivedIRQ = false;

 

WaitForIRQ();

}

 

Sure this code ''looks'' OK, but some emulators or floppy drives might manage to be faster than your code. What if you've just returned from

set it to false again and then infinitely loop, waiting for an IRQ that has already been received. It's usually better to do something like:

 

volatile byte ReceivedIRQ = false;

 

outb(Controller.FIFO, headload_ndma);

}

 

== Related Links ==