19 Sep
2007
19 Sep
'07
3:34 a.m.
On Tue, 18 Sep 2007, Michael B. Brutman wrote:
Does anybody remember how these connect to a PC or
XT?
Obviously there is the DB37 which has the signals. On one version of
the drive (the 720KB version) there is just the signal cable, and no
power pigtail or external power - power must come through the DB37
cable, but the technical reference for the floppy controller doesn't
have any pins that provide power. Was there a special card that passed
the signal wires through and added +5 and +12 to the DB37 going to the
drive? (Maybe on pins 1 - 4, which are supposed to be unused?)
On the other version I have there is the power pigtail, which is
obviously where the power comes from. The pins on the power pigtail are
connected to pins 1 - 4 on the DB37.
Some of the EARLY 5150 cases (mine had a white power switch, with a black
power supply), had a knock-out for a DB25 and a small round knock-out that
we presumed was for cabling power to external drives (which would be a bad
idea with a 63.5 W power supply). They also had an additional drive
mounting screw up from the bottom. Eventually IBM realized that that
wasn't such a good idea - prob'ly after a few got tightened enough to warp
drive castings?