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SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.

The Southern California OS/2 User Group
USA

SCOUG OS/2 For You - July 1998

Dear Mr. Know-It-All

Mr. Know-It-All always has the answers to even the really tough questions.

Q. Dear Mr. Know-It-All,

I'm running Warp 3 and Warp 4 on my two machines. In the BIOS for both computers is a hard drive setting for LBA. What, exactly, is LBA, and are there any OS/2 incompatibilities?

A. LBA is Logical Block Addressing. The motherboard BIOS includes an Interrupt 13 routine that calculates a drive's cylinder (10 bits), head (8 bits) and track sector (6 bits). These 24 bits are sent to the drive to identify the desired sector. However, an IDE drive only allows for 16 heads (4 bits), so the maximum number of sectors you can specify is what 10+4+6 bits can hold, or 1,048,576 sectors (the other 4 "head bits" are ignored). Since each sector holds 512 bytes, that's 536,870,912 bytes. (The actual capacity is slightly smaller since the sector value may not be zero. This leads to the 528,482,304 byte, or 528 MB, IDE limitation.)

When LBA is selected, however, the motherboard BIOS Interrupt 13 routine uses an IBM extension (functions 40h-48h) which allows 32 bits as a drive "sector number". (Since 32 bits can hold 4,294,967,296 values and each sector is 512 bytes, you can have an IDE drive with a capacity of 2 terabytes.)

That's why you can't write some data onto a drive and then switch back and forth between "NORMAL" and "LBA" mode. The motherboard BIOS will identify a different, incorrect sector on the drive. If you're just reading, you'll only end up with incorrect data, but if you're writing, data will be both lost and destroyed.

With a brand new large drive, set it to LBA and leave it that way. OS/2 and LBA coexist fine together, but be sure to use the latest drivers.

Q. Dear Mr. Know-It-All,

I keep seeing and hearing claims that your money is better spent if you upgrade your peripherals instead of your cpu. How do you know what to do?

A. Watch the graph of your cpu activity. If it has a lot of flat spots on top, upgrade your processor. If not, upgrade your peripherals.

Q. Dear Mr. Know-It-All,

Is there any particular type of diskette storage unit you like best?

A. I presume you aren't still backing up on floppies, and instead need to store small sets of, say, one or two diskettes.

I use Ziplok sandwich bags. They keep the dust out, and the diskettes will stay dry if the roof leaks (I like to plan ahead). I put any notes I've scribbled onto pieces of paper in with the diskettes, so the "file" is complete, and I keep them on the bookshelf with my books, in whatever section they belong (i.e., Programming, Internet, Word Processing, Graphics, etc.). I use the same system for CD-ROMs. I've had no "static electricity" problems with this method.

Curious or in doubt, ask Mr. Know-It-All. He gets email at MrKIA@SCOUG.COM.

Mr. Know-It-All lives in Southern California.

The Southern California OS/2 User Group
P.O. Box 26904
Santa Ana, CA 92799-6904, USA

SCOUG is a trademark of the Southern California OS/2 User Group.
OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation.
All other trademarks remain the property of their respective owners.