[Coco] hard disk performance

[Tony Cappellini]

>>I've looked up the specs on the Internet for the ST31270A and ST296N and
>>found the following for 512 byte sectors. My ST296N is formatted for 256
>>byte sectors and I don't know what effect that might have if any on speed.

The default bytes per sector can easily be changed with a SCSI Mode Select
command, although non512-byte sectors isn't very common.
I've  been in the hard drive industry for a long time.  I've only seen  one
company that requested a sector size other than 512 bytes, but in most cases
the end user has no idea of the actual setting, unless they check it.

Another feature which could affect the data transfers is if the drive is
doing synchronous or asynchronous transfers.  Having a host adapter capable
of doing synchronous transfers would be more expensive and complicated and
out of the reach of coco hobbyists. I doubt the coco could keep up with a
drive transferring data that fast.

SCSI drives can also be formatted for sector interleaves greater than 1:1
which could affect the transfer rate on the coco, if the drive was low level
formatted that way. I would expect the driver has this hard coded to an
optimum value though. This feature was only used in the very early days-
even before the coco ;-)

I agree with the fact it is most likely the coco which is the bottleneck.