Floppy disk-related knowledge and interrupted access via BIOS

First, floppy disk basic knowledge Introduction (1) 3.5 inch floppy disk

• The 3.5-inch floppy disk is divided into upper and lower sides with 80 tracks on each side, and each track is divided into 18 sectors, each with a sector size of 512 bytes.

• Floppy disk size calculation: 2 Side * 80 Tracks * 18 Sectors * 512 bytes = 1440KB≈1.44MB

(2) 5.25-inch floppy disk

• 5.25-inch floppy disk each track has only 15 sectors, and the other is the same as a 3.5-inch floppy disk. Therefore, the 5.25-inch floppy disk size is 1.2MB

Physical access to the disk is performed by the disk controller. We can access the disk by controlling the disk controller. You can read and write to a disk only in sector units. In the read/write sector, give the forward sign, track number, and sector code. The face number and track number start at 0, and the sector area code starts at 1.

Second, using the BIOS of the Int 13h interrupt access to the disk

If you access the disk by directly controlling the disk controller, you need to involve many hardware details. The BIOS provides interrupt routines to read and write sectors, which complete a number of complex and hardware-related work, and we can access the disk by invoking a BIOS interrupt routine.

To be continued .....

Floppy disk-related knowledge and interrupted access via BIOS