[CoCo] 720kb vs 1.4mb 3.5" disks

[John E. Malmberg]

I have been having a number of floppy disk issues that are somewhat 
related to this topic in my quest to transfer my Flex-09 disks to an 
emulator.

Battle number 1.  A 5.25" 360K floppy drive went bad on head 1 in such a 
way that it prevented head 1 from operating on the 3.5" 1.44M floppy 
drive that was with it.

A great deal of time was wasted trying to find out what was going wrong.


Battle number 2.  During the troubleshooting of this, I built another 
disk system with different 360K 5.25 inch drive and a 1.44M floppy 
drive.  Basically replaced everything.

It seems that there is a small alignment problem with the second 1.44M 
floppy.

The floppy drive on the W98/W2000 and separate W95 system will not read 
COCO formatted 720K diskettes made on the second drive.  But I assumed 
that the problem was my software, and wasted a lot of time putting in 
diagnostics in the program.

The properly aligned 3.5" drive in the COCO does not have problems 
reading the COCO formatted floppies made in with the problem 3.5" drive, 
but the reverse is not true.

Battle number 3.  In trying to rebuild the subsystem that had the bad 
5.25" drive, if I have only a 5.25" inch drive in it, it appears to work 
fine.  If I add a known good 3.5" drive to it, it causes track 0 of the 
5.25" media to become corrupted.

This is all with double density media, not high density.

I have discoverd that John Collyer's version of the retrieve utility can 
  not read track 0 of a flex formatted floppy, and can not read side 2 
of the floppy, but appears to be able to read every other track on side 1.

-John
wb8tyw at qsl.net
Personal Opinion Only