21 Sep
2014
21 Sep
'14
6:18 p.m.
On 09/21/2014 04:54 PM, Ali wrote:
Earl,
Thanks. I saw that (linked through Bill's site). I agree a lot of
good info. The Adaptec card is an interesting choice. I would not
have suspected it to be that capable. I am planning on using a
CompatiCard which does both SD and DD 8" drives. I just need to get
my hand on a nice 8" drive.
Careful that that Compaticard is a CC IV, and not a I or II. As the
latter came out before the 5170, the port conventions are different from
the standard AT-type and the CC IV. You will probably be disappointed
if you use the CC I or II.
Regarding Adaptec SCSI cards with floppy controllers. The magic device
is the National Semi DP8473 FDC. It's also present on some Future
Domain 16-bit ISA controllers, as well as Ultrastor and some DTC ones.
One cute trick that I thought I reported on is that the 8473 has
fully-decoded 4 drive support--and is capable of driving a floppy with
no added buffering. Just a matter of bringing the drive select leads
out. Both the DTC and Ultrastor controllers do this using some unused
pins on the floppy connector for the added motor and drive selects. It's
quite easy to add a small couple of wires to the Future Domain cards to
provide the same 3rd drive (on the same cable) support. The Tulin 3rd
floppy driver can be used with DOS.
Naturally, utilities that use direct hardware access don't care about
BIOS support or drivers. E.g., 22Disk and IMD will work just fine with
a third drive.
One other interesting tidbit is that some of the DTC controllers have a
couple of jumper blocks to allow 4 drives on the same cable. The gotcha
is that drives are all configured for a "flat" cable and each uses a
different drive select. Motor control is the same for all 4
drives--turn one motor on, they all come on. A fair compromise for
convenience.
--Chuck