View Full Version : scsi

05-19-2001, 05:29 PM
hey, sorry to sound like a moron here, but i have hardly any scsi experiance. what is are twisted pair cables? what are the proformance boosts, ect. Any additional scsi info would be appreciated
Thanks a lot


05-19-2001, 10:30 PM

I am not an expert on this subject but I'll tell you what I know from experience. The Miles2 is an Ultra2 wide LVD card designed for LVD drives, so the kit includes Initio twisted-pair cable for LVD and an LVD terminator. The normal LVD Granite cables are flat, not twisted, and my guess is that the high quality of the cable coupled with their superior LVD terminators is the reason the cable is not twisted. However Granite tech tells me that for very long custom lengths of LVD cable, and I have forgotten beyond what length he said, they make custom twisted-pair LVD cables to go with their LVD terminators.

So twisted-pair is for LVD systems, the LVD cards and LVD drives. For the same purpose, Granite uses special flat cable for normal lengths and even the Gurus 10-bay Burly box uses the Granite flat LVD cables and LVD terminators. Personally I like the Granite stuff. The various types of Granite stuff are explained here http://www.macgurus.com/shoppingcart/obj_show_page.cgi?mgscsiteflonintcables.html k

[This message has been edited by kaye (edited 19 May 2001).]

05-19-2001, 11:37 PM
The reason for twisted pair cabling is to reduce the possibility of interference between the adjacent wires. Some ethernet cables are also constructed this way.

I assume from the sheer bulk(and cost) of the Granite cables that their individual wires are sufficiantly sheilded so as to make this unnecessary.

But I could be wronghttp://macgurus.com/infopop/emoticons/icon_smile.gif

05-20-2001, 03:35 AM
Granite flat TPO cabling has signal properties comparable to TPO twisted-pair, yet is more affordable, until you get to the longer lengths. Granite doesn't transition to twisted-pair until you get to part number GD1005, for example: eight internal connectors with 12-inches distance between stubs, and a good 18-inches between internal and external connectors. Stretched end to end, this cable exceeds 10-feet in length.

the GD1005 is a wild cable. Talk about spaghetti all over the place! You have to be careful with it: you can tear it if you let it get away from you.

anyway. The whole intent behind twisted-pair is reducing cross-talk, noise and interference. Considering the faster sync rates inherent in the LVD SCSI specs, you need good insulators, good connectors, good media and good wiring all put together correctly to minimize signal errors and optimize data integrity and performance.