Breaking the 137GB Storage Barrier
A-2 Maxtor D540X-4G
Past barriers often frustrated people trying to add a new hard disk to an older system
when they discovered that not all of the designed capacity of the hard disk was
accessible. This inability to access the entire drive is referred to as a “capacity barrier”
and it has been seen and overcome many times in the computer and disk drive
industry.
The 137-gigabyte barrier is the result of the original design specification for the ATA
interface that provided only 28 bits of address for data. This specification means a hard
disk can have a maximum of 268,435,456 sectors of 512 bytes of data which puts the
ATA interface maximum at 137.4 gigabytes.
10MB
16MB
32MB
128MB
528MB
2GB
4GB
8GB
33GB
10
100
1,000
10,000
100,000
1,000,000
10,000,000
1980 1985 1990 1995 2000 2005
137GB
5.x
4.x
3.x
DOS
Win95A
Win 3.x
Win98
Win95(osr2)
Win2000
WinME
WinXP
10 megabytes:early PC/XT limit
16 megabytes: FAT 12 limit
32 megabytes: DOS 3.x limit
128 megabytes: DOS 4.x limit
528 megabytes: Early ATA BIOSs without BIOS extensions
2.1 gigabytes: DOS file system partition limit
4.2 gigabytes: CMOS extended CHS addressing limit (not widely experienced)
8.4 gigabytes: BIOS/Int13 24-bit addressing limit
32 gigabytes: BIOS limit
