Performa 6400/200 not reading/writing 800k disks

[cmosless]

I needed to copy some applications over to my Macintosh Plus, and the only working Macintosh I have that should be able to do this is my Performa 6400/200. Although it has a dead PRAM battery, the machine works just fine, but I noticed some odd behavior with the floppy disk drive, and I can't quite figure out what's wrong.

The drive reads and writes to 1440k floppies perfectly. No issues, will format every time, respects the write-protect switch, and so on. However, when I tried using a 800k disk in the drive, initially it would recognize the disk, but fail to copy files to it or format it. This was the behavior it exhibited the first time I tried using 800k disks in the drive (after not powering it on for a few years). Now it simply will say the disk is write-protected, no matter what I do (including putting tape over the write protect switch). However, if I take a 1440k disk and cover the HD hole with tape (bad idea, I know), it works just fine as a 800k disk. Formats every time, reads/writes fine, and even will boot my Macintosh Plus.

The 800k disks I am using all function properly on my Macintosh Plus (both in the internal and external drives), and I have even tried different brands of disk with the same results. Does anyone know what the issue might be, and how to fix it?

Thanks.

 

[rsolberg]

Try putting a piece of tape on an 800k disk in the same location you did on the 1.4MB disks. I wonder if the density detect switch is weak or out of alignment and perhaps the tape adds sufficient thickness to depress the switch.

Edit: do this with an 800k disk that has been formatted on your Plus to eliminate potential format mismatches from earlier attempts on the Performa.

 

[Unknown_K]

What OS are you using, I think you need to use OS 7.5.x or older to properly read and write the 800K floppies. I use a 68K machine for my disk making, no issues.

 

[rsolberg]

Mac OS 9.2.2 is the latest system that can read, write, and format 800k disks. Every release from System 3 to Mac OS 9.2.2 is fully compatible with 800k disks if a compatible drive is used. The beige G3s and PowerBook G3 Series "Wallstreet" are the latest Mac models to have or support a floppy drive capable of reading or writing 800k disks.

I expect you're thinking of the 400k/MFS limitations beginning with 7.5.x which can read and write, but not fornat those disks. 7.6.x can read, but not write 400k MFS disks. OS 8 and later cannot read or write 400k MFS disks.

See: http://siber-sonic.com/mac/newmillfloppy.html#formatsum

 

[BadGoldEagle]

What OS are you using, I think you need to use OS 7.5.x or older to properly read and write the 800K floppies. I use a 68K machine for my disk making, no issues.

Also, keep in mind that the file format changed ever so slightly between 7.1 and 7.5. I can't create any bootable 800k disks for my Plus using my SE/30 running 7.5. 1.44Meg ones work though.

But yeah if you don't really care about bootable disks, anything up to 9.x will do the job. I am creating 800K HFS disks all the time using my Sheepshaver virtual machine.

 

[cmosless]

Sorry for the late response, I did figure out why the disks were appearing as locked. The Performa had 7.6.1 installed on it, I went ahead and downgraded to 7.5.3 from an installation disc and now all of my 800k disks are appearing as they should - unlocked. However, now I am now experiencing the original issue I had. I went ahead and did a little testing, I formatted a 1.44mb disk and copied some files to it on the Performa, and everything worked as it should. Then I took an 800k disk and did the same on my Mac Plus, again, no issue. I then took the same 800k disk and inserted it into the Performa. The files appeared there, as they should - read fine, but when I attempted to copy files over to the disk, I got an error stating that verification failed due to a disk error, asking if it should continue copying, and upon continuing, no files ended up being copied. When I re-inserted that disk into the Plus, I got another error saying that the disk was damaged and that it needed to be initialized. I also experienced similar issues trying to format the disk on the Performa, it simply fails to format and the disk will have to be initialized on my Plus for it to be usable again. Disk Copy also fails to write disk images to the disk as well, giving an error code -80. I also attempted this with tape covering the density hole, as suggested by rsolberg, with no effect, and repeated the same test with other 800k disks to eliminate the cause of bad disks (unless, somehow, all of my disks went bad,which would be odd since they are from different brands, and are stored in the same environment as all my other good disks).

So, tl;dr, the Performa reads/writes/formats 1440k disks fine, but can't write or format to 800k disks and apparently is damaging them as well when I try to write to them. I'm not sure what to do at this point, perhaps I need to clean the floppy drive? Any help will be appreciated.

 

[Macdrone]

Yep could need a good head cleaning or replacement as at this age some of them floppies just may be giving out.  I have a wet floppy cleaner I use with tech tool to clean mine.

 

[cmosless]

Well, I decided to remove the floppy drive and manually clean it (and spent a solid 15 minutes trying to remove the front bezel without snapping it in half, the manual makes it look so easy :-/ ). I cleaned what appears to be a mix of tar/dust caked onto the exposed circuit board (previous owner was a smoker), and then I cleaned the heads with a cotton swab and alcohol. The drive was of Panasonic brand. I reassembled it, tested the drive with a working 1.44mb disk, and everything seemed to work as normal. Then, I tried a 800k disk, same disk errors I was getting pre-clean while copying/modifying files, but when I attempted to format, I experienced some different results.

One out of every few format attempts, a window reading "Updating disk... Space available: 800k" (same format as attached image) will appear on screen for about a second, before the disk ejects and the format fails. I then attempted to format the disk as PC 720k (something I had not attempted before), and it displayed the same window, though progress was actually being made...at the rate of anywhere between 3 to 5k every 20 to 40 seconds. An hour or so later, the format eventually failed, and instead of the generic 'format failed' message, it also mentioned the disk was defective (not true, disk is in good condition and verified so on both the Plus and on a 486 DOS machine as well).

At this point, I am considering replacing the drive, as I'm not sure what else there is that I can do to fix this. If anyone has any idea, any help would be appreciated.