21 Dec
2012
21 Dec
'12
12:23 p.m.
On Fri, 21 Dec 2012, geneb wrote:
On Fri, 21 Dec 2012, Chuck Guzis wrote:
That won't work for most drives. You need also the disk change signal on
pin 2 instead of using pin 2 for density select or density reporting. Many
non-pc applications require disk change on pin 2 for proper operation,
otherwise you take a major risk with screwing up a disk when you put in a
different disk and then write to it.
Such a board also wouldn't help with disabling the drive's internal 1.44MB
sensor/mode. I've run into a number of applications where people have been
successfully using 1.44MB media in their 720K drives, so if they simply
install a 1.44MB drive without disabling or altering the 1.44MB sensor,
the 1.44MB drive then tries to operate in high density mode with those
high density disks that have been formatted as double density in a 720K
drive.
Ideally you should never be "hacking cables", you just need the right
drive that has the correct shunts/jumpers so it can be configured for
whichever non-pc application. That swapping 2 pins idea just doesn't work
properly for most applications, and is incredibly risky with the great
many non-pc applications that use 720K drives that rely on having a proper
disk change signal on pin 2.
On 12/21/2012 08:11 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. :) Not really. Most of the Compaq desktop machines
I've seen use drives
with no faceplate because the face is part of the front of the case.
I guess it depends. I've certainly got some with full bezels and a Compaq
sticker on them. I think Dell also used these drives. At any rate, you
can find them very inexpensively and they work in quite a number of
situations that would be very difficult for a plain white-box Teac FD235HF.