[Coco] hard disk performance

[Robert Gault]

Chuck Youse wrote:
> I consistently get 24-25 seconds on my 80GB Seagate and 27-28 seconds on
> my 1.2GB ST31270A, which yields approx 42K/sec and 38K/sec,
> respectively.
> 

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.

ST31270A
Data transfer rate   11.000 MB/S int
                      16.600 MB/S ext PIO4
ST296N
Data transfer rate    1.250 MB/S int
                       1.500 MB/S ext ASYNC

With the above as the limitations of the hard drives, the limiting 
factor would appear to be the slow Coco clock speed and/or the driver code.
It also "explains" the test result ratios of ~40K/sec for the AT31270A 
vs ~12K/sec for the ST296N. The 31270A should be faster by ~10x but the 
drivers are using 6809 sta vs 6309 tfm with a nod to the faster tfm opcode.