Network: Select a drive with care

CD-Rom drives are an international standard, but all drives are not the same. By Bob Kane
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The Independent Culture
WITH ALL the talk about Digital Versatile Disk (DVD), and the promise that this high-capacity technology will bring to computer users, no one has paid much attention to the lowly CD-rom drive. A standard the world over, CD-rom drives have enabled multimedia functionality on the PC as well as providing a low-cost, relatively fast installation mechanism for today's multi-megabyte applications.

You may think all CD-rom drives are the same, save for their X factor, the number used to describe the spin speed of the drive, such as 24X or 32X. This month's PC Magazine examines 15 of the fastest CD-rom drives to discover that there are differences beyond the X factor. One is that, with rotational speeds up to 7,000rpm, the manufacturing quality of the disk you play in your CD-rom drive is very important. If a disk is not manufactured to sufficiently high standards, some of today's high-speed drives slow down in order to try and read the data. This results in erratic or reduced performance.

CPU time required for moving data from a CD-rom disk to memory was also found to be quite low, as long as direct memory access (DMA) support is enabled under Windows 95 for enhanced, integrated-drive electronics (EIDE) CD-rom drives. Most CD-rom drive manufacturers either didn't bother, or poorly documented how to enable this feature, and some even suggested that their drives didn't support DMA transfers. But all the drives in the survey supported DMA and performed better when DMA-enabled.

DMA was not an issue for small computer system interface (SCSI) drives as they have their own efficient protocol for transferring data from the disk to memory. However, the majority of PCs out there today don't have a SCSI connection.

PC Magazine also discovered that, depending upon when a drive was manufactured, its performance characteristics could vary dramatically. This is due to rolling production changes on the manufacturing line for the firmware that controls the drive operation.

PC Magazine chose the Philips 32X-Max PCA323CD as its Editor's Choice. Its respectable overall performance scores, reasonable CPU utilisation, ability easily to handle disks of varying manufacturing quality, and a one-year replacement swap-out warranty, all at a price of only pounds 47 (ex- VAT), proved that all CD-Rom drives are not the same.

You can read the full report in the September issue of `PC Magazine' or at