--- Lyndon Tiu <[EMAIL PROTECTED]> wrote: > SCSI standards also changed over time with not so > much backwards compatibility. > > If anything new comes in the USB/Firewire standards, > hopefully, backward > compatibility remains. Unlike the SCSI we have in > old LCs which are not > compatible with modern day SCSI.
SCSI has excellent backwards and even forwards compatability. I currently have a Fast/Wide 17gig 7,200 RPM drive connected to the external SCSI port on my Radius 81/110. That port is Standard/Narrow, or max 5 megabytes/second and 8 bits wide. This works because the specifications of the newer SCSI versions were written to include the ability to "drop down" to lower speeds and narrower bus widths to maintain compatability. That ensures that newer devices can work on older interfaces and older devices can work on newer interfaces. USB 1.1 and 2.0 use the same 4 pin connectors. USB 2.0 devices are supposed to work at 1.1 speed when connected to that interface, though most of them really don't work too well due to the need for the higher bandwidth. That's just a limitation of trying to squeeze all the traffic of a multilane freeway down a two lane road by raising the speed limit to 120 miles per hour. ;) USB 1.1 devices work on a 2.0 interface because the newer interface detects them and slows down when sending data back and forth. I'd say SCSI has better backwards compatability than USB 2.0 devices because for SCSI it was made almost mandatory that newer, faster devices had to be able to slow down and function properly when connected to an older, slower interface. There are some SCSI devices (especially High Voltage Differential) that cannot be adapted to slower controllers, but they're expensive and specialized for uses where there's never a need to do so. Almost all higher speed USB 2.0 devices require a USB 2.0 controller or they'll just "fall on their face" when it comes to actually using them, even if by definition of the USB standard they "work". Just for fun I installed a DVD-ROM drive in a USB 1.1 external case and connected it to a i.1 port on my PC. It's about 50~60% fast enough to play movies. If the DVD player software was able to setup a huge software buffer, it'd be useable, but doing things like pausing or reversing would not be fun. Thus DVD playing requires USB 2.0, even if you have an external drive that's 1.1 compatable. If the drive was SCSI, it might have a little trouble on standard/narrow, but I bet just playing a movie would proceed without problems, because the drive is sending 8 bits at a time instead of 1 like USB. FireWire uses a 6 pin connector, most of the time. Some devices have a 4 pin connector, which requires an adaptor or special cable. Now FireWire 800 uses a 9 pin connector. Waitaminute! Weren't these new interfaces supposed to REDUCE complexity? Laptop bags have exploded anew with USB and FireWire cables and adaptors for all the various "better ideas". If only when the USB spec was being written, they had commanded "Thou shalt use this ONE connector type, NO EXCEPTIONS!" ;) But noooo. There's Type A (the original), Type B (the smaller, square one), and at least three different "mini" USB connectors created by Sony and other companies for their cameras and other devices. My Kodak DC-280 uses a proprietary multi-pin round DIN connector that combines USB and RS-232 ports plus composite video output and who knows what all else. (Fortunately it uses Compact Flash cards and has no internal RAM so it's not a problem.) I haven't counted all the different FireWire connector styles, but I bet FW800 and variants thereof will at least double the number there are now. WHY HAS THE COMPUTER INDUSTRY TOTALLY FORGOTTEN WHAT THE @[EMAIL PROTECTED]@# THE WORD "STANDARD" REALLY MEANS!!!!!! ===== It will be total Fandemonium, Summer 2005! Check website for further info. http://www.fandemonium.org __________________________________ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250 -- Vintage Macs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Vintage Macs list info: <http://lowendmac.com/lists/vintagemacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[email protected]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/vintage.macs%40mail.maclaunch.com/> iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com
