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06.01. Should I use my interface's device drivers?




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This item is from the Yet Another Enhanced IDE/Fast-ATA/ATA-2 FAQ, by John Wehman and Peter den Haan with numerous contributions by others. (v1.92).

06.01. Should I use my interface's device drivers?

Yes. Often these drivers are essential to get any kind of performance out of your interface.

The PIO or DMA mode used when transferring data is determined by the interface card. Some cards have jumpers that determine the speed in hardware; these work in the fast mode from the microsecond you switch on the computer.

Most interfaces, however, are software configurable. At bootup, they default to the slowest possible speed. Somewhere during the boot process, a piece of software belonging to your adapter figures out what kind of transfer rates the drives support and configures the controller chip to match. There are a couple of cases to distinguish:

o Onboard I/O with full BIOS support. The controller is fully configured when your computer boots. You can usually set the desired mode for each harddisk in the CMOS setup. Many modern boards fall in this category.

o Onboard I/O with incomplete BIOS support. For some unfathomable reason, some mainboards do not support or only imperfectly set up their integrated I/O ports. In that case, you'll have to use DOS or other drivers to get full functionality.

o Interface card with BIOS. This is similar to the two categories above. The main difference is that these cards don't necessarily have setup screens; in that case, they must use other means to determine the transfer mode to be used. For example, the Promise 2300+ uses a combination of jumpers and a table in ROM containing the parameters for a number of different drives. It may or may not be necessary to use drivers for best performance.

o Interface card without BIOS. Since there is no way the mainboard BIOS can know how to set up all those different interface cards out there, you must use the supplied device drivers to profit from the fast modes. That is, unless your card is hardware configurable using jumpers, which is quite rare.

Usually, there are drivers for other operating systems as well, such as Windows, Win95, OS/2 and so forth. These serve a couple of purposes.

o The driver may be necessary to configure the adapter as described above. This doesn't apply to Windows, where the DOS device driver usually has already done that job.

o The standard drivers built into operating systems don't support all of the advanced features of your interface and drives. Examples are 32-bit transfers, block mode and DMA.

o Windows only: the standard driver (*wdctrl) that ships with Windows and Windows for Workgroups has some serious restrictions. See Q8.10 for details.

In view of this it is rather unfortunate that so often, the drivers supplied with an interface are of mediocre quality.

 

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