HD Tach is a physical performance hard drive test that uses a special kernel mode VXD to get maximum accuracy by bypassing the file system. A similar mechanism is used in Windows NT/2000.

The HD Tach sequential read test is a little bit different from other benchmarks. Most benchmarks create a file on the hard drive and test within that file.

The problem is that modern hard drives use a zone bit recording technique that allows different read speeds depending on where the data is located. Data on the outside of the drive is much faster than data recorded on the inside.

HD Tach reads from areas all over the hard drive and reports an average speed. It also logs the read speeds to a text file that you can load into a spreadsheet and graph to visually read the results of the test.

In addition to sequential read, HD Tach tests the drive's random access time. Random access is the true measure of seek speed. Many drives advertise sub 10 millisecond seek speeds, but seek speeds are misleading.

Finally, HD Tach tests the drive burst speed. The burst speed is the speed that data can be accessed from the drive's on-board read-ahead memory. This measures the speed of the drive and controller interface.

The non-commercial version of HD Tach gives you access to all the functionality, ease of use and reliable benchmarking you expect from HD Tach. In addtion, we have added the ability to save benchmark results and graph your saved benchmark results against previous results or results from the new, included, drive database.

We have created this database from benchmark results sent in by our users through the new 'Upload' feature of HD Tach - after running the test you are given the option to send your drive benchmarks in to Simpli Software for inclusion in our database.

The non-commercial version of the software may also be used for up to 14 days by commercial users as an evaluation, as stated in the license agreement.