SCSI Cable question...

[RDMustang1]

I just bought a nice 68pin scsi hd and have a hard time spending $25 on a scsi cable.. a friend has a 50pin scsi cable with converters to 68pin.. if I attach this to my scsi card will it hinder the performance? iow, does the number of pins make a difference in terms of speed? Thanks!

 

[rmd2001]

I think performance will drop.

 

[corkyg]

Performance will drop. 50-pins is SCSI 2. 68 is SCSI 3. You will transfer data at SCSI 2 rates.

 

[DoctorBooze]

If your SCSI card only has a 50-pin connector, no, performance won't drop. If your SCSI card has a 68-pin connector, yes, you'll get a reduced transfer rate. On the other hand, depending on what speed of SCSI you're running (fast, ultra, ultra-2, ultra-3) and whether you've other stuff on the SCSI bus, it may not matter, e.g. if you've got ultra-2, which can do 40Mb/s on a narrow (50-pin) cable, and a not-too-fast hard drive (7200rpm or under 30GB), and nothing else, you probably won't notice the difference.

 

[DoctorBooze]

<< Performance will drop. 50-pins is SCSI 2. 68 is SCSI 3. You will transfer data at SCSI 2 rates. >>

corkyg: NO! SCSI-2 and SCSI-3 are protocol specifications, not electrical specifications, and define what commands are expected to work.

The electrical things are: 50-pins is Narrow. 68 is Wide. Fast is 10MHz. Ultra is 20MHz. Ultra-2 is 40MHz. Ultra-3 is 80MHz. Narrow transfers means one byte per cycle, so Fast/Narrow is 10Mb/s. Wide transfers means two bytes per cycle, so Fast/Wide is 20Mb/s. Ultra-3/Wide is 160Mb/s.