Many things will affect the performance of digital audio software in general, and multi-track production software in particular. The performance of the disk drive being used to store the audio data is only the beginning. Naturally, this component must be of optimum efficiency in order to allow real time streaming at a high track count.    However, this isn't necessarily always going to be the limiting factor in a DAW's performance. There are other places to look as well. Modems: Having a modem plugged into a DAW's PCI bus can lead to conflicts, particularly if the modem is a voice modem. Some production software will attempt to configure the modem as a sound card. While more "aware" programs such as Cakewalk will report a modem upon finding it and allow you to ignore it as part of the sound system setup, other programs may not, and could default to a lower bit depth or sample rate as a result. Many DAW users agree that an external modem connected to one of the computer's serial ports is the safest way to go... Read More »

The SCSI interface is an old timer. Before there was IDE, there was SCSI. It was used not only for disk drives, but scanners, printers and even to interface the PC with synthesizers and automated sound and light boards. For a long time, SCSI was the only really high performance disk interface, and in early versions, high performance was a whopping 5 MBytes/sec. WOW! Remember, that was in the time before the PC-based DAW, before Windows and before a person could buy a PC with more than 1 meg or RAM. Here's a quick rundown on SCSI. The History of SCSI In 1980, SCSI amounted to a proposed interface whose specifications occupied little more than 20 pages. Compare that with the more than 600 pages used to describe the interface standard today. In 1985, a group of manufacturers got together and started pressing for ANSI to define SCSI. This came to pass in 1986 with the publishing of the first SCSI standard, now referred to as SCSI-1. This new interface standard consisted of a controller card, often called a host... Read More »

IDE, or more formally, IDE/ATA, is the most common system for connecting a hard drive to a PC. In modern systems (to which this discussion is limited), they plug directly into the motherboard through a 40 pin cable. Most motherboards offer 2 separate IDE channels and thus 2 connectors on the board. Each connector can support 2 IDE devices, be they disk drives, CD drives, tape drives, removable drives and so on. If a channel has 2 devices on it, one must be designated a master and the other a slave. This is done simply by moving or removing a jumper on the drive itself. As a result of this configuration, any system can have 4 IDE devices connected to it. Using an external controller board connected to the PCI bus supporting 2 additional channels, up to 8 devices and be supported on a PC. This is the limit, and attempting to add 4 more devices with an extra controller will consume more interrupts and other system resources. This contrasts with modern SCSI which can have up to 15 devices on a controller and... Read More »

By default, IDE disk drives transfer data to and from the system using a protocol called "Programmed Input/Output" or PIO. This technique requires the CPU to get into the middle of things by executing commands that shuffle the data to or from RAM and the drive. Thus, the CPU is tied up doing the work of fetching and stuffing. Also, the time overhead involved in putting data in the cache, reading each byte into the CPU, sending it out to the cache again and then routing it to its destination puts a top end to the speed of the transfers. In typical desktop systems this isn't much of a problem. The system doesn't have much to do during these transfers anyway, so who cares? Even if a user has several applications open at once, seldom is more than one actually doing anything, and during disk I/O, the application will likely be idle anyhow. Now suppose you have an activity known as "streaming" going on which is pulling lots of data from the drive in real time while the application doing the streaming is simultaneously... Read More »

What is the difference between regular DMA and bus mastering? Plenty! Bus Mastering Logistics First, let's look at bus mastering again but from a DMA point of view. A bus is a data transport. Bus mastering is a very advanced means of transporting data to and from devices and/or memory using the PCI bus as a conduit. A device that issues read and write operations to memory and/or I/O slave devices is considered the master, although a master device can have slave memory and/or I/O ports available to be accessed by other masters. For example, an Ethernet controller must convey data it receives from over the LAN and must also access data to send over the LAN as a bus master, but acts as a slave when the CPU, acting as a master, programs it to initialize and to specify where it must get and put data. Only one bus master can own, or "drive" the bus at a given instant, and the bus is responsible for arbitrating bus master requests from the various bus master devices. A bus master device will request access... Read More »

So how do you get this so-called Bus Mastering to work anyhow? First, let's make sure your ducks are in a row. You must have the following squared away: 1) A motherboard with the proper chip set for bus mastering. The 430 FX, HX, VX, TX and 440 FX, LX, EX, BX, GX chipsets from Intel will support UDMA bus mastering as well as the VIA chip set and some other competing chip sets. 2) A disk drive that is Ultra DMA compliant. Most new drives are. 3) Windows 98, Windows 95 OSR2 or above, or Windows NT with service pack 3 (at least!) installed. How can you tell if you have this condition met? If you have Windows 98 installed, you're ready to rock. If you are running Windows NT and don't know if you have service pack 3 installed, then you aren't the one to be messing with NT and you need to call in whoever it is that normally administers your system. If that's you and you still don't know what I'm talking about, sell your system and buy a Windows 98 system. You'll be better off. Otherwise, NT users please... Read More »

When it comes to picking a drive for a DAW, you have a bit of a job ahead of you. We looked at the two contending controller formats in the last sections, but that's just an overview. What about the specifications? What do you need to know about a drive's performance in order to make an intelligent choice regardless of which format you're interested in? As it turns out, the specifications of both the drives and the controllers can lead you quite clearly to the best choice so long as you don't lose track of what you're after. You want a disk for a DAW - not a file server - so many of the drive specs and controller advantages don't apply and others will count more heavily. On the other hand, you're not just going to be typing email or surfing the net on this system either, so not "just any old drive" will do. Decision Criteria To an extent, the drive format you have already committed to will be a big factor. If you don't want to support a large number of drives and CD devices, IDE will look like the best... Read More »

In comparing IDE and SCSI it is important to understand that both types of drive are, from a "between the shells" point of view, the same. Inside the Drive Hard disks have a sealed case with one or more platters of magnetically coated media, a small synchronous motor designed to rotate the platters at a precise speed, and an actuator with one or more arms attached, each with a read/write head at the tip. The platters hold the data in the form of concentric tracks, each split like a pie into many sectors. Each sector will hold 512 bytes of user data as well as error correction information and other alignment information. The actuator is designed like a speaker voice coil, extending or retracting along its throw path depending on the strength of an electrical signal in the coil which will force it very precisely to any location. The arms attached to the actuator are thereby positioned to various places above the spinning platters where the heads can pick up or lay down streams of magnetic information. The... Read More »

Introduction Look in any newsgroup devoted to DAW discussion and sooner or later there will be some sort of mention regarding favorite hard disks or preferred disk formatting techniques or optimum parameter settings or SOMETHING about the impact of specific hard drives on the performance of audio streaming. Often, the argument starts with the personal preference between SCSI and IDE disk drives. Why "personal preference"? We think that after going over the data in this article, you will see that there's a lot of room for subjective opinion in this discussion. Far from proving that there is one clear winner between the two, research has proven just the opposite. There is a lot to be said for SCSI. On the other hand, many readers are about to say "A-HA! I knew SCSI was better!" and are about to be disappointed. This will come as a shock to many hard core SCSI advocates - perhaps even an insult! However, before proponents on either side start sending us an HTML flame-thrower, look over the data here and keep... Read More »