Evolution of Hard Drive

The commercial usage of hard disk drives began in 1956 with the shipment of an IBM 305 RAMAC system including IBM Model 350 disk storage

The IBM 350 Disk File, invented by Reynold Johnson, was introduced in 1956 with the IBM 305 RAMAC computer. This drive had fifty 24 inch platters, with a total capacity of five million characters. A single head assembly having two heads was used for access to all the platters, making the average access time very slow (just under 1 second).The IBM 1301 Disk Storage Unit,[6] announced in 1961, introduced the usage of a head for each data surface with the heads having self acting air bearings (flying heads).

1980s to present day:
1980 - The world's first gigabyte-capacity disk drive, the IBM 3380, was the size of a refrigerator, weighed 550 pounds (about 250 kg), and had a price tag of $40,000
1986 - Standardization of SCSI
1989 - Jimmy Zhu and H. Neal Bertram from UCSD proposed exchange decoupled granular microstructure for thin film disk storage media, still used today.
1991 - 2.5-inch 100 megabyte hard drive
1991 - PRML Technology (Digital Read Channel with 'Partial Response Maximum Likelihood' algorithm)
1992 - first 1.3-inch hard disk drive - HP Kittyhawk
1994 - IBM introduces Laser Textured Landing Zones (LZT)
1996 - IBM introduces GMR (Giant MR) Technology for read sensors
1998 - UltraDMA/33 and ATAPI standardized
1999 - IBM releases the Microdrive in 170 MB and 340 MB capacities
2002 - 137 GB addressing space barrier broken
2003 - Serial ATA introduced
2005 - First 500 GB hard drive shipping (Hitachi GST)
2005 - Serial ATA 3Gbps standardized
2005 - Seagate introduces Tunnel MagnetoResistive Read Sensor (TMR) and Thermal Spacing Control
2005 - Introduction of faster SAS (Serial Attached SCSI)
2005 - First Perpendicular recording HDD shipped: Toshiba 1.8-inch 40/80 GB
2006 - First 750 GB hard drive (Seagate)
2006 - First 200 GB 2.5" hard drive utilizing Perpendicular recording (Toshiba)
2006 - Fujitsu develops heat-assisted magnetic recording (HAMR) that could one day achieve one terabit per square inch densities.
2007 - First 1 terabyte hard drive (Hitachi GST)
2008 - First 1.5 terabyte hard drive (Seagate)
2009 - First 2.0 terabyte hard drive (Western Digital)
2010 - First 3.0 terabyte hard drive (Seagate)
2010 - 2.5 & 5-platter 3TB Hard drives expected, manufacturer claims by TDK and Western Digital
2011 - 4TB Hard drives expected, Hitachi claim

2010 - 2.5 & 5-platter 3TB Hard drives expected, manufacturer claims by TDK and Western Digital
2011 - 4TB Hard drives expected, Hitachi claim

This excellent chart shows the evolution of IBM hard disks over the past 15 years. Several different form factors are illustrated, showing the progress that they have made over the years in terms of capacity, along with projections for the future. 250 GB hard disks in laptops in five years? Based on past history, there's a good chance that it will in fact happen!

Note: that the scale on the left is logarithmic, not linear, and PC hard disks have one actuator.