This page displays screen captures of charts created by HD Tach.   The charts give good indications of the drive's burst read speed as well as the continuous speed from the platter's edge to the centre.

Maximum theoretical burst speeds are around 33Mb/s for UDMA drives and half that for PIO Mode 4.  In practise however, most drives will not reach these limits due to their construction.  It is worth noting that simply because a drive has a particular interface (eg. UDMA) that it is still not likely to perform fully to that spec.

If you would like to add screen captures of your own HD Tach results to this page, please forward them to me in GIF format with all relevant information regarding the specifications of the drive under test.

Seagate Medallist Pro UDMA vs Quantum Fireball ST PIO Mode4

This is my own 7200 rpm Seagate Medallist Pro UDMA drive running under Win98 with Microsoft Busmastering drivers.  It is one of the fastest IDE drives currently available and the chart reflects that.  The average read speed of over 12MB/s is more than enough for any recording project and with the busmastering taking the workload off the CPU, it only requires around 3% of my processing power.  This drive running without busmastering utilizes over 90% of my CPU

My second drive is a 4500 rpm Quantum Fireball ST 3.2GB running in PIO Mode4.   This drive is typical for a quality Mode 4 component and demonstrates the jump in performance made by the Latest UDMA drives like the Madeallist Pro above.  Even so, an average read speed of nearly 5MB/s is still more than enough for hard disk recording.  

This chart shows how busmastering can help improve both the burst read speed and in particular the load on your CPU.  This drive consumes 1.2% CPU under busmastering, but increases that to over 50% without.  The burst read speed also increases by 50% over non-busmastering.  Note that the continuous read speed remains roughly the same for both modes.