CoCo Floppies: Was:These darned old computers

From: Lawrence Walker <>
Date: Thu Aug 29 00:11:16 2002

 Damn ! So now I can't even be sure of any of my fdd's marked NG (since I
stupidly forgot they could be 720meg ones). Googling the model #s on old
drives is also pretty hazardous or unproductive given all the company fall-
outs. Kind of like sussing out old memory chips using chip #s or FCCs.
 So, Check them out installed, and then check them out installed on another
computer. There's got to be a better way.


> > > Sure, if you look just inside the dust flap on a 3.5" drive, and you see a
> > > switch {or optical sensor) on the right hand side, it's a 1.44Meg - that's
> > > the 1.44Meg sense switch to see if it has a HD disk in it. If the switching
> On Thu, 29 Aug 2002, Tony Duell wrote:
> > Be very careful. Some early 3.5" drives (including the 600 rpm
> > full-height Sony units) put the disk-detect sensor on the right. Well, it was
> > a logical place to put it, out of the way of the write-protect sensor, before
> > there were 1.44M disks. So a sensor on the right need not imply a 1.44M drive.
> And some of the early 1.4M drives that IBM used had no 1.4M/730K sensor!
> It would try both densities in read attempts, and you could
> specify in software to write the lower density (for example:
> FORMAT A: /T:80/N:9 ), but if you put in a 720K diskette and tried to
> format, the drive would have no way to know that it was not a 1.4M.
> > Incidentally, such drives often won't work _at all_ with 1.44M disks. The HD
> > hole lines up with the disk-detect sensor so the drive thinks there's no disk
> > inserted.
> At least that way, it never misinterpreted a disk as the WRONG type.
Received on Thu Aug 29 2002 - 00:11:16 BST

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