Serial ATA
Andrew W. Hill - 2001.12.05
My Turn is Low End Mac's column for reader-submitted articles. It's your turn to share your thoughts on all things Mac (or iPhone, iPod, etc.) and write for the Mac web. Email your submission to Dan Knight .
A while back I wrote about SCSI. Personally, I love SCSI. Its intelligent, fast, and efficient. Standard parallel ATA is just plain dumb. With the new Serial ATA specification, however, they've given ATA more of a brain.
First of all, I'd like to voice my largest complaint about the Serial ATA protocol - it's being called "ATA/1500." They rate it at 1500 Mbps (which for some reason comes out to 150 MBps). This is just like FireWire being rated at 400 Mbps and USB 1.0 at 12 Mbps. And it's just the opposite of the MBps (megabytes per second) ratings for SCSI and UltraATA.
Why can't developers decide on a standard set of units? People are shouting about how much faster Serial ATA/1500 is than UltraATA/100. At first glance, it looks like its 15 times as fast, but you have to deal with the difference between bits and bytes. ATA/1500 is only 50% faster than UltraATA/100. This is still significant, but it involves confusing advertising methods.
Serial ATA is a point-to-point process. This is going even further away from SCSI than where ATA is now. Instead of having sixteen, or seven, or two devices (master and slave) per port, Serial ATA can only have one device per port. A controller card would have between two and six ports with a four pin connection for each. Hubs are not allowed. This is probably not a bad thing, as it is easy to troubleshoot bad cables and devices without worrying about device interactions.
The current parallel ATA cable uses 80 lines and a 40-pin connector. 26 of these 40 wires are data lines (the rest, presumably, being grounds). As the Serial ATA cables have four conductors, the cables are very thin. This means that it is feasible to have a separate cable for each device without the insides of the computer becoming cluttered with excess cabling. It also leads to better ventilation. In Macs this is less of an issue than in PCs, due to the positioning of the hard drives, but it still helps. For reference, the Serial ATA cable will be just a bit larger than an internal CD audio cable.
Serial ATA purportedly has a significantly improved DMA (direct memory access). Many of the intelligent functions that were unique to SCSI are in the specification. In addition, the star topology of the drives allows for reliable RAID systems to be implemented.
Despite this increased intelligence, Serial ATA should be available at the same price as parallel ATA. Due to its speed and increased intelligence and the continued low price, it is expected that Serial ATA could displace SCSI. Maxtor notes that there is no reason why ATA drives have lower physical specifications, other than those that want high performance drives usually want SCSI. With Serial ATA it is quite possible that there will be 15,000 rpm ATA/1500 drives on the market.
It is interesting to note the relationship between Serial ATA and FireWire. IEEE 1394 was in the SCSI-3 specification as one of the "alternate" SCSI types, along with Fiber-Channel. Serial SCSI has been around for a few years, and despite promised speeds of 150 Mbps (which were expected this year) they never arrived. Serial ATA has been listed as an internal-only protocol, like the current parallel ATA, so it won't be competing with FireWire for external devices.
If Serial ATA proves to be everything it promises, it may mean the demise of SCSI. Maybe it's worth it.
Andrew W. Hill (a.k.a. Aqua) has been using Macintosh computers since 1987 and maintains that the Mac SE is the perfect Macintosh, superior to all - including the Color Classic. He is on the verge of being evicted from the family home due to its infestation of Macs (last count: about 50). Andrew is attempting to pay his way through college at UC Santa Cruz with freelance web design and Mac tech support.
Share your perspective on the Mac by emailing with "My Turn" as your subject.
Join us on Facebook. Follow us on Twitter.
Recent My Turn articles
- Back to Mac OS 9 Because It's All I Need, 2011.01.26. Sebastian Patting sold his Intel Macs and went back to PowerPC Macs and Mac OS 9. Here's why.
- Using Low End Macs for Internet Radio, 2008.08.18. When the local public radio station moved classical music to HD radio, it was time to find another way to listen. An old iMac with iTunes solved the problem.
- 'That's Not a Computer', 2008.07.30. Salvaging a broken PowerBook by turning it into a desktop computer.
- More in the My Turn index.
Links for the Day
- Mac of the Day: Mac IIfx, introduced 1990.03.19. This 'wicked fast' 40 MHz Mac trumped the 33 MHz DOS world.
- February 14 in LEM history: 98: A perfect compact Mac - 00: Extended computer warranties worth the cost? - Making your PC work with your Mac - 01: Customize Microsoft Word - 02: Quadra revives a passion for computing - 03: Real world performance - DIY Pismo screen replacement - Best Mac for writing - 03: Fastest browser on the Mac - 06: 15" MacBook Pro - Impressions of a newly acquired Lisa - Finding and using free WiFi - Apple should liberate OS 9 - 07: New Mac mini cheaper than upgrading a Power Mac - 08: Falling in love with OS X
- Support Low End Mac
Recent Content on Low End Mac
- Fix Home Button Delay, Tablet the Ultimate Mobile PC, iPad Notebook a Possibility, and More, iOS News Review, 2012.02.10. Also using your iPad at work, two photo editors, a new iPad text editor, Macally's magnetic iPad 2 stand, and more.
- White MacBook Goes End-of-Life, Logitech Touch Mouse Supports Gestures, Firmware Updates, and More, The 'Book Review, 2012.02.10. Also MacBook Air better than any Ultrabook, docks for MacBook Pro models, Intel offers improved SSDs, and more.
- Mac and iOS Browsers: Options Galore, Freeware Forum, 2012.02.10. Safari is adequate on Mac and great on iOS, but the range of good alternatives is stunning. LEM writers share their favorites.
- Apple's Support Lead Shipping, Smartphones Outsell PCs, OS X Ported to ARM by Intern, and More, Mac News Review, 2012.02.10. Also the power of Tex-Edit Plus, Google and Twitter are already censoring the Web, Snow Leopard Security Update, and more.
- LogMeIn: Remote Screen Sharing for the Rest of Us, Alan Zisman, Zis Mac, 2012.02.09. Configuring the Mac's built-in screen sharing to work over the Internet can be difficult or impossible. LogMeIn makes it easy.
- 15 Years Ago Motorola Unveiled the PowerPC G3, Low End Mac Round Table, 2012.02.06. The G3 processor was optimized for real world Mac software and made a big leap forward in efficiency.
- Don't Kill Caps Lock, Learning to Love the iOS Keyboard, and an Adaptive iPad Keyboard, Charles W. Moore, Miscellaneous Ramblings, 2012.02.06. The Caps Lock key has a useful function, the iPad's keyboard really is useful, and checking out an adaptive keyboard for the iPad.
- More links in our archive.
Recent Deals
- Best 17" MacBook Pro Deals
- Best iPod classic Deals
- Best eMac Deals
- Best MacBook Air Deals
- Best iBook G4 Deals
- Best iPad Deals
- Best Classic Mac OS Deals
- Best Apple TV Deals
- More deals in our archive.
About LEM Support Usage Privacy Contact
Follow
Low End Mac on Twitter
Join Low End Mac
on Facebook
Low End Mac Reader Specials
TypeStyler 11 is now in the Mac App Store!! -- Special Introductory Price of $59.95!! -- To Buy From The Mac App Store Click Here Now!! Or buy direct
from Strider Software.
Don't install Parallels to play poker online! Poker Mac will show you how to download and install a native Mac poker and Mac Casino applications in minutes.
Favorite Sites
MacSurfer
Cult of Mac
Shrine of Apple
MacInTouch
MyAppleMenu
InfoMac
The Mac Observer
Accelerate Your Mac
RetroMacCast
PB Central
MacWindows
The Vintage Mac Museum
DealMac
Deal Brothers
Mac2Sell
Mac Driver Museum
JAG's House
System 6 Heaven
System 7 Today
the pickle's Low-End Mac FAQ
Affiliates
Amazon.com
The Apple Store
The iTunes Store
PC Connection Express
GainSaver
Parallels Desktop for Mac
eBay
