WD1770 help needed - test-drb@ccmp.vtda.org

4 Feb 2000

On Feb 4, 11:43, Ethan Dicks wrote:

...
  --- Pete Turnbull &lt;pete(a)dunnington.u-net.com&gt;
wrote: 
...
   The 1772 was
designed to be a plug-in replacement.  The main (only?)
 difference is in the programmed step rates. 
 I am looking at a WDC-1772.  It has 28 pins.  Doesn't the 1770 have 40 pins?

No, you're thinking of a 1790.  1770 and 1772 are both 28-pin devices.
 There's also a 1772-2 which is just a mask revision of the 1772, and a
1772-2-2 which can run faster.  Ataris sometimes have the latter.

...
  The standard 5.25" drives _do_ use GCR for all
native formats, but the later
...
  stuff (1570/1571) also do MFM for CP/M compatibility. 
The aforementioned 1581
...
  is a 3.5" device (~720K; the not-released 1591
was ~1.44Mb) and does have some
...
  form of MFM-capable chip, AFAIK.  You can read 1581
disks in other machines,
...
  Linux included, I think. 
I didn't know that.  Did Commodore machines use a standard controller to
write the MFM, or did they use the same techniques as for the GCR?  I know
Amigas can read/write DOS disks, but they don't have any sort of standard
controller.

-- 

Pete						Peter Turnbull
						Dept. of Computer Science
						University of York