Would it be unsafe to make the driver default to 20 MHz instead? That
would avoid this problem from other first-time NCR + UW users.
I just went and re-read the help in this section and it had a few
things to say that are misleading:
> Specify 0 if you want to only use asynchronous data transfers.
> Otherwise, specify a value between 5 and 10. Commercial O/Ses
> generally use 5 Mhz frequency for synchronous transfers. It is a
> reasonable default value.
This is why I went with the default. Are asynchronous transfers a
bad idea? I am not familiar with this aspect of SCSI.
> However, a flawless singled-ended scsi bus supports 10 MHz data
> transfers.
Hmm. This is why I suspect that this section is out of date! The new
NCR 895 even supports 40 Mhz... I wonder how many drives will support
this. 8^)
Thanks,
Mark
p.s. this is why free software is the greatest... the Linux community
has definitely earned Infoworld's best tech support of 1997 award.
On Wed, 25 Mar 1998, Mark Lehrer wrote:
> ncr53c875-0-<0,0>: SLOW WIDE SCSI 10.0 MB/s (200 ns, offset 15)
^^^^^^^^^
> NCR53C8XX SCSI support (CONFIG_SCSI_NCR53C8XX) [Y/n/?]
> ...
> synchronous transfers frequency in MHz (CONFIG_SCSI_NCR53C8XX_SYNC) [5]
^
Since you selected a maximum synchronous transfer frequency of 5 MHz, the
maximun transfer speed is indeed limited to 10 MB/s (16 bit times 5 MHz).
To get Ultra-SCSI speeds, you have to select 20 MHz.
Disclaimer: I don't have a NCR53c875 and I don't know whether the driver
supports 20 MHz.
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