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- Path: sparky!uunet!usc!chaph.usc.edu!news
- From: baffoni@aludra.usc.edu (Juxtaposer)
- Newsgroups: comp.sys.atari.st
- Subject: Re: Difference between SCSI and SCSI 2?
- Date: 28 Jul 1992 12:58:49 -0700
- Organization: University of Southern California, Los Angeles, CA
- Lines: 41
- Message-ID: <l7b9npINN3ma@aludra.usc.edu>
- References: <1992Jul27.122717.20063@crc.ac.uk>
- NNTP-Posting-Host: aludra.usc.edu
-
- In article <1992Jul27.122717.20063@crc.ac.uk> naffara@crc.ac.uk (Dr. N.A. Affara) writes:
- >Can anyone tell me what the difference between SCSI (1) and SCSI 2 is?
- >Or for that matter the difference between SCSI and for example IDE?
- >(apart from the fact that they use different connectors)
-
- Sure.
-
- SCSI-1: First SCSI standard - specified an 8-bit bus that has a peak
- throughput of 4MB/s, with a maximum of 8 SCSI devices possible (though one is
- designated controller with the other 7 slave devices). It uses a 50-pin ribbon
- cable or a 50-pin Centronics style cable, or Apple uses a 25 pin cable.
-
- SCSI-2: Next major release of the SCSI standard. Specifies 16-bit bus
- (but can handle 8-bit devices for backward compatibility) and, between two
- fully SCSI-2 compliant devices, can reach peak transfer rates of 16MB/s, with a
- sustained transfer rate of up to 10MB/s. SCSI-2 provides for multiple acces-
- sing of devices on the SCSI bus - data can be written from one device to up to
- 7 other devices (SCSI-2 maintains the 8 device limit) simultaneously, but they
- all get the same info. I believe (not sure about this one) that each SCSI-2
- device can become bus master, so DMA between SCSI-2 devices is possible.
- SCSI-2 uses the same cabling as SCSI-1.
-
- IDE: This is the successor to the MFM/RLL drives. It can pretend to
- be any MFM/RLL device of the same (or lesser) size, and will automatically
- translate the heads/sec.per track/cylinders to the correct values of the media
- transparently to the computer. It is an 8-bit bus, with maximum 4MB/s (I
- think, but never saw it of course) with a maximum of 2 devices that can be
- connected to the same controller. Their primary advantage is the cheap cost
- of manufacture (and the subsequent cheap resale price). IDE uses a 40pin
- ribbon connector (I have yet to see an external IDE drive, so that may be the
- only valid type of cable).
-
- >Thanks
- >Phil
- >(E-mail naffara@uk.ac.crc)
-
- No prob.
-
- -Mike
-
-
-