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November 18, 1996

Windows 95B is a questionable user investment for now

Microsoft Corp. is distributing through computer manufacturers a version of Windows 95 that current users of Windows can't upgrade to. This version is officially called OSR2 (which stands for OEM Service Release 2). If you type VER in a DOS window under OSR2, you see "Windows 95B" -- which is what I'll call this version in this column.

Windows 95B's most important feature allows Windows users to stop wasting almost 40 percent of the space on their hard disks. This space is now wasted by the inefficient storage scheme used by FAT-16, the 16-bit file allocation table that was introduced with DOS. Windows 95B supports FAT-32, a 32-bit file allocation table. FAT-32 breaks the old 2GB limit on the size of a drive letter (technically, a drive partition). Drives can theoretically be as large as 140 terabytes (140,000GB) with FAT-32.

With FAT-16, small files -- even those only 1 byte in length -- consume a 32KB disk cluster on most drives. Here is the smallest amount of disk space that each file can consume on FAT-16 drives of various capacities:

On average, every file wastes one-half of a cluster. Depending on the average size of your files, this wastes about 40 percent of your disk space if your hard drive is larger than 1GB.

FAT-32 raises the limit of clusters that can be in a partition and at the same time reduces the size of each cluster. This is the cluster size with FAT-32 for various partition sizes:

After disks grow past 32GB (which they will), we'll be right back at the inefficient, space-wasting 32KB cluster. But for now, anyone with a hard drive smaller than 8GB can regain about 40 percent of the wasted disk space simply by converting to Windows 95B.

But that's a problem. Microsoft has no plans at this point to release a utility that will upgrade a Windows 95 system to Windows 95B with FAT-32. To get Windows 95B, you have to purchase a whole new system from one of the PC makers that received master disks in time for Christmas. Microsoft plans to release FAT-32 with Windows' next major release, code-named Memphis, in mid-1997.

Buying a whole new PC just to get Windows 95B hardly seems like a good investment. And FAT-32 still has its problems. Microsoft's DriveSpace won't compress a FAT-32 drive (although it will recognize one). Every current disk utility package will need to be upgraded to work with FAT-32. And although older utilities may simply give you an "unrecognized partition" message if you try to run them on a FAT-32 system, beware. Older disk defragmenters may cause serious damage.

Until Microsoft releases a utility for the rest of us to upgrade to FAT-32 (and to convert back if it doesn't work with our existing software), I can't recommend using Windows 95B. More on this next week.

FAT-16 cluster limitations

Partition size Cluster size
256MB to 511MB 8KB
512MB to 1,023MB 16KB
1,024MB to 2,047MB 32KB

FAT-32 cluster limitations

Partition size Cluster size
512MB to 8GB 4KB
8GB to 16GB 8KB
16GB to 32GB 16KB
More than 32GB 32KB

Brian Livingston is the co-author of Windows 95 Secrets Gold and four other Windows books (IDG Books). Send tips to or fax: (206) 282-1248.

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Copyright © 1996 by InfoWorld Publishing Company


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