Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!iphase!phan
From: phan@iphase.UUCP (Tai Phan PER)
Newsgroups: comp.periphs.scsi
Subject: SCSI controller chip
Summary: 5MB/s transfer rate and SCSI compliance
Keywords: MB87035
Message-ID: <340@iphase.UUCP>
Date: 17 Jan 91 16:15:49 GMT
Reply-To: uunet!iphase!phan
Distribution: comp.periphs
Organization: Interphase Corp. Dallas TX
Lines: 23

Hi,

I have a design that use the Fujitsu SCSI controller chip MB87035.

According to the datasheet of the chip, it can run up to 5MB/s SCSI
transfer rate at 10MHz clock.  But there is a note that if the clock
is faster than 8MHz (or 4MB/s transfer rate) there are timings that
the chip may not comply with the SCSI spec.  For example, at 10MHz
clock, the period is 100ns, the SCSI spec for selection phase is
1200ns, the chip spec is 11Tclk - 30 = 11*100 - 30 = 1070ns.  

I spoke to Fujitsu, they said that with the timings in SCSI-I spec,
particular the deskew delay (45ns), assertion period (90ns), negation
period (90ns), data hold time (45ns)... there is no way that one can run
at 5MB/s and fully comply with the spec.???

Does anyone know a SCSI controller chip that runs at 5MB/s and still
fully complies?  This is just the SCSI-I.  Please Email me at 
uunet!iphase!phan

Thank you for you help.

Tai Phan