[Coco] 3.5 in 720K vs 1.4 meg floppy diskettes

[Gene Heskett]

On Saturday 13 December 2003 07:04, Robert Gault wrote:
>Gene Heskett wrote:
>> On Friday 12 December 2003 21:07, KnudsenMJ at aol.com wrote:
>>>In a message dated 12/10/03 11:08:11 PM Eastern Standard Time,
>>>
>>>bugster at cedarcomm.com writes:
>>>>1.44MB 3.5" Floppy drive acting as a 720k drive.....works great!
>>>>I've put together several dual floppy drives with this
>>>>configuration and it works great with DD 720k floppy disks.  My
>>>>current config at home is this configuration (/DO is a 360k 5.25"
>>>>floppy and /D1 is a 1.44MB Floppy).
>>>
>>>Have
>>>
>>>> yet to have a DD 720k disk fail on me (even formatted as 160k in
>>>>RS-DOS!).
>>>
>>>This makes sense, since the drive electronics sense whether it's a
>>>DD or HD diskette in there and adjusts the write current
>>>accordingly.  But keep reading ...
>>>
>>>> Putting a 1.44MB floppy disk in and formatting it as double or
>>>>single density (720k or 160k under RSDOS)....sucks!  Very
>>>>unreliable.
>>>
>>>Hmmm, sounds like the drive fails to upgrade the write current for
>>>the HD floppy.  Maybe the OS has to help out in this, since you
>>>seem to get better results under OS-9 than BASIC.  Or did I miss
>>>something?  --Mike K.
>>
>> I think its related Mike.  I have 3 3.5"drives here, all recent
>> purchases, and they refuse to do a 720kbyte format on an HD
>> diskette. I've come to the conclusion that they self adjust the
>> data recovery pll for a 500 khz data rate when they sense the HD
>> hole, and therefore cannot deal with a 250 kilobaud data rate even
>> during the write phase, usually error out of that within the first
>> 2-3 tracks.
>>
>> Taping up the hole results in a format that doesn't quit during
>> the write phase, but has a very poor performance during the verify
>> phase, often marking a major portion of the disk out as unusable. 
>> Put a regular DD diskette in, and everything is cool.  I have
>> several hundred of those from my amiga days so I'm set for a
>> while.
>>
>> Currently I've a major problem.  The boot is failing because I
>> rebuilt one of my utility packs thats loaded during the boot by
>> the startup script.  Unforch, when I did the re-merge using merge,
>> I then forgot to set the x and px attributes, so when the startup
>> script gets to that line it outputs an error 214, followed by a
>> 221 and hangs the boot.  No response to anything but the reset
>> button at that point. Is there any way to cause it to bypass the
>> startup and drop directly to a shell, thereby allowing me to fix
>> it?
>
>I don't remember anything like a key press that will bypass the
> Startup file. However, brute force could be used here.
>
>Use a raw disk editor either from a good OS-9 boot or Disk Basic to
>change the name of the Startup file on the corrupted disk; S to X
> for example. Then when OS-9 starts, it won't find a Startup file.

To do that, I'll need someone to email me a .dsk that is a floppy only 
boot, and that I can then ezgen the stuff I've got, or can get, from 
the one copy of the hd boot floppy into, and that would let me access 
the drive to  fix it.  I don't have a floppy only boot that I know 
of.  But I'll look around, and test everything I've got just in case 
I do find one thats floppy only.

Right now its woozy out, I was on the mountain last night, overhauling 
an AK2-25 breaker whose mechanics are showing signs of wear, and 
which has 100% WV-engineered undervoltage riggings in it.  I had to 
make additional swinging room for the motion of the latch/trip lever, 
lubricate the rollers, adjust the latch engagement & etc.  Thankless 
work, but it now closes on command the first time everytime.  And it 
now trips open when its supposed to.  Last time we got a mouse in the 
HV, it didn't, and we blew two fuses at the substation feeding us.  
Not to mention a considerable hunk of 3/8" thick micarta terminal 
strip got carved away by the fire the mouses demise caused. 

Thats hard on 4000 lb plate transformers and the 750 mcm wireing 
feeding us too.  Yeah, I play with fire sometimes, BIG fire.  Been 
doing it for 40 years now.

-- 
Cheers, Gene
AMD K6-III at 500mhz 320M
Athlon1600XP at 1400mhz  512M
99.22% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.