Stereo audio was not immediately available due to data input and output limitations on hard drives of that time.
In 1993, iZ Technology Corporation developed RADAR (Random Access Digital Audio Recorder distributed by Otari), designed to replace 24-track tape machines.
In this form, complex tasks can be automated, freeing the audio engineer from performing a final mix in real time.
A personal computer can be used as a hard disk recorder with appropriate software; nowadays this solution is often preferred, as it provides a more flexible interface to the studio engineer.
The major constraints on any hard disk recording system are the storage capacity, transfer rate, and processor speed.
Examples of notable stand-alone hard disk recorders and manufacturers include Alesis, Akai, Fostex, Korg, Mackie, TASCAM, Roland Corporation, Yamaha Pro Audio, RADAR and Zoom HD8 and HD16.