Toshiba Corp. said it has developed four new super-slim 2.5-inch hard disk drives with the world's highest capacity of 20 gigabits per platter, or 35.1 gigabits per square inch.

It will begin mass production of the new products in July, expecting the drives to bring high data storage capacity to the fast evolving market for portable personal equipment, the electronics maker said Monday.

The four new drives -- two of a ball-bearing motor type and two with fluid dynamic bearings -- will give portable personal computers increased capacity for operating systems and large video sources, the company said.

Both types come with one or two platters, offering a capacity of 20 or 40 gigabits.