21 Dec
2012
21 Dec
'12
11:09 a.m.
On 12/21/2012 10:35 AM, geneb wrote:
I'd like to build a little adapter board that has
all the line tweaks
needed to use a 3.5" drive with 720k media in older CP/M machines. A
few option jumpers and you wouldn't have to hack cables any longer. :)
Well, the Samsungs do have READY available on pin 34 and can run in
1.6MB mode as a direct substitute for 8" drives (i.e., spindle speed is
360 RPM). If you wanted to do a paddle board to adapt the 34 pin header
to an edge connector, you could also add jumpers for DS0-3, rather than
ask the user to hand-solder different jumpers to the drive PCB.
I guess one serious question is "Do you want to have the drive be
insensitive to the media-type hole in 3.5" disks?" While many people do
use 3.5" DSHD floppies with the hole taped over for 720K use, I do
question the advisability of this, particularly given the terrible
quality of late-manufacture DSHD 3.5" floppies.
It's sort of a turnabout. Back in the late 80s, when DSHD media was $50
a box, you'd see lots of DS2D media formatted as DSHD and punches were
even sold to add the hole to the jacket. It might seem strange, but I'd
have a lot more faith in one of those surviving 20 years of storage than
a modern DSHD floppy back-converted to a DS2D.
--Chuck