davewh@microsoft.UUCP (03/13/91)
There has been talk here of problems with Quantums. First, the prodrives don't do low-level formats - they're already formatted at 1-1 interleave and they have a disk-cache built onto the controller (I think it's 32k big). Anyway, one doens't need to do low-level formats on Quantum Prodrives. If you try, it comes right back instantly saying "Success." Next, someone used the term "supplying terminating power to the bus." This isn't quite right. For general info, termination is really a few resistors that have the same impedance as the SCSI cable. This way, electric waves don't bounce back and forth along the SCSI bus, thereby avoiding lots of confusion among the devices. These bouncing waves a are serious problem with high-frequency communications. Take a look at Ethernet cabling sometime - each end is terminated with a little resistor. At the same time, you don't want too much termination (more than one set of resistors) because now the impedance won't match and you'll get bouncing waves again. Make sure there is only ONE set of terminating resistors at each END of the chain. Quantum drives are generic SCSI drives. I have an 80meg prodrive hooked to my Rev C card - no problems. I bought the thing from some mail order place with an ad in the back of macweek - best prices around. Anyone who tells you quantum drives don't work on a // is full of it - Apple brand drives are Quantum mechanisms! What you *do* need to do is set the SCSI ID of the drive correctly. There are 3 jumpers on the controller labled ID 0, ID 1, and ID 2. They represent bits of the ID #. To set to #3, you'd put jumper joiners on ID 1 and ID 0. Without any jumpers, the drive is 0. If you have 2 devices with the same ID, things will get confused (like recognizing a disk now and not in 2 minutes). Hope this is helpful. Dave Whitney Microsoft My own opinions. I wrote Z-Link and BinSCII.
bazyar@ernie (Jawaid Bazyar) (03/15/91)
In article <9103142212.AA07966@beaver.cs.washington.edu> davewh@microsoft.UUCP writes: > >There has been talk here of problems with Quantums. > >First, the prodrives don't do low-level formats - they're already >formatted at 1-1 interleave and they have a disk-cache built onto the >controller (I think it's 32k big). Anyway, one doens't need to do >low-level formats on Quantum Prodrives. If you try, it comes right >back instantly saying "Success." Not exactly- I low-level formatted my Quantum with my RamFast, it took about 30 seconds. I've heard here before that the Quantums just ignore the interleave, always using 1:1. Also, I think the Quantum (my new 40meg anyway) has a 64k cache. >Next, someone used the term "supplying terminating power to the bus." The RamFast manual uses that term. It's somewhat confusing. >Quantum drives are generic SCSI drives. I have an 80meg prodrive >hooked to my Rev C card - no problems. I bought the thing from some >mail order place with an ad in the back of macweek - best prices >around. Anyone who tells you quantum drives don't work on a // is full >of it - Apple brand drives are Quantum mechanisms! I agree. Check out Aurora Industries- $235 for a 40meg ProDrive, 12ms access (with cache). They also have factory refurbished drives for incredibly low prices, and a 6 mo warranty. -- Jawaid Bazyar |"I'm sure K&R have never heard of Mike." Senior/Computer Engineering | bazyar@cs.uiuc.edu |"That's okay. I'm sure Mike's never heard of K&R". Apple II Forever! | (discussion about Orca/C)