Re: 5.25 floppies that read but don't write
Do we know the make/model of this drive? - Original Message - From: Marc Verdiell marc.verdi...@gmail.com To: cctalk@classiccmp.org Sent: Saturday, August 22, 2015 12:50 AM Subject: RE: 5.25 floppies that read but don't write Chuck, I looked at the pin 2 signal and resulting drive behavior. It doesn't properly auto-switch between densities as it should. It does switch it for reading, but not for writing. Below is the full story. There is one jumper that controls DD/HD switching mode. In the auto position, I can read both HD and DD formats (I use the right diskettes for either format). You can see the computer on pin 2 (density select) trying both positions, settling on the right one (high for HD, low for DD), and reading the disc correctly. That's great. But when writing, although pin 2 goes to the right level, the floppy seems to ignore it. It will always write at DD, and refuse to write in HD (no signal at the head). Interestingly, in the fixed density position (should be HD only), it WILL write at 1.2M HD! The write signal does appears at the head. Unfortunately in this setting it will NOT switch the reading, get stuck reading only DD and fail on HD. So I can either have the reading HD or the writing HD, but not the two at the same time. That's why a regular format fails. The density switching logic seems to have a problem. Rather than track down which IC or transistor failed on the board it might be much simpler to get another 5.25 floppy. In the meantime my understanding of these simple critters has improved a lot. Marc At high density, have you taken a good look at pin 2 of the floppy interface? Have you checked to see if pin 2 is configured (via jumpers) as density select? --Chuck
RE: 5.25 floppies that read but don't write
Chuck, I looked at the pin 2 signal and resulting drive behavior. It doesn't properly auto-switch between densities as it should. It does switch it for reading, but not for writing. Below is the full story. There is one jumper that controls DD/HD switching mode. In the auto position, I can read both HD and DD formats (I use the right diskettes for either format). You can see the computer on pin 2 (density select) trying both positions, settling on the right one (high for HD, low for DD), and reading the disc correctly. That's great. But when writing, although pin 2 goes to the right level, the floppy seems to ignore it. It will always write at DD, and refuse to write in HD (no signal at the head). Interestingly, in the fixed density position (should be HD only), it WILL write at 1.2M HD! The write signal does appears at the head. Unfortunately in this setting it will NOT switch the reading, get stuck reading only DD and fail on HD. So I can either have the reading HD or the writing HD, but not the two at the same time. That's why a regular format fails. The density switching logic seems to have a problem. Rather than track down which IC or transistor failed on the board it might be much simpler to get another 5.25 floppy. In the meantime my understanding of these simple critters has improved a lot. Marc At high density, have you taken a good look at pin 2 of the floppy interface? Have you checked to see if pin 2 is configured (via jumpers) as density select? --Chuck
Re: 5.25 floppies that read but don't write
On 08/21/2015 09:50 PM, Marc Verdiell wrote: Chuck, I looked at the pin 2 signal and resulting drive behavior. It doesn't properly auto-switch between densities as it should. It does switch it for reading, but not for writing. Below is the full story. On 5.25 HD drives, pin 2 is generally a drive *input*. That is, the host telegraphs what's needed, not the drive. This is different from the 3.5 world, where HD and 2D floppies have a mechanical means (density aperture in the jacked) to indicate what's needed. Some drives/systems can work together so that the drive determines which media type is inserted and notifies the host. But not in the 5.25 word. --Chuck
RE: 5.25 floppies that read but don't write
Thanks Chuck. Looks like you are on to something, I'll search in this direction. Unlikely it has anything to do with the disks themselves, which were blank. The 500 kHz write signal present on the connector just doesn't make it to the head, whereas the 300 kHz does. On the other handm something along what Chuck suggests could create this exact problem. I'll let you know how it goes. I am aware of the narrow track problem of 360k written by HD drives, so I have other native 360k DD drives for that purpose. For now I just want my HD drive to behave as one ;-) At high density, have you taken a good look at pin 2 of the floppy interface? Have you checked to see if pin 2 is configured (via jumpers) as density select?Various drives have different jumperings for pins 2 and 34 (and sometimes 4). For example, I deal with some Japanese CNC gear that uses pin 2 for disk change and pin 34 for read (and pin 4 for in use. --Chuck So I tried to force formatting in DOS at 360k, and sure enough it worked! I can then read the diskette back, write on it, etc... And of course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive setting that would prevent it to write at high density but let it do at low density?
Re: 5.25 floppies that read but don't write
Re: Degaussing floppies. Only part of degaussing a floppy is getting a strong enough degausser--I use on made for wiping VHS carts--it gets very hot after only about 3 minutes of use and the thermal cutout belays my impatience until it cools off. So it's definitely not wimpy. However, to use it, you have to observe the correct mumbo-jumbo. You press it against the floppy in question, hit and hold the power button and *slowly* pull the disk away, moving said disk in a roughly circular motion. A quick check using Kyread shows no discernible magnetic pattern remaining. On a related matter, I've found that using a very strong rare earth/neodymium magnet (i.e. if you get your fingers between it and a hunk of iron, you should not be surprised with broken bones or severe tissue damage) on a bad high-density 3.5 floppy, followed by a pass with the degausser will often return the floppy to usability. This comes up occasionally when I'm asked to repair a factory-labeled floppy that's developed issues. You want to keep the original labeling and short of inserting a new cookie, this approach actually works. For what it's worth, I use the magnets with large steel ball bearings to roll dents out of sheet brass--so I do have a valid reason for having one around. This goes to an observation that DSHD 3.5 media appears to develop some sort of fatigue after a certain number of write passes. For what little it's worth, Chuck
RE: 5.25 floppies that read but don't write
Date: Thu, 20 Aug 2015 13:57:05 -0700 From: ccl...@sydex.com To: gene...@classiccmp.org; classiccmp.org:On-Topic and Off-Topic Posts cctalk@classiccmp.org Subject: Re: 5.25 floppies that read but don't write On 08/20/2015 01:04 PM, Marc Verdiell wrote: So I tried to force formatting in DOS at 360k, and sure enough it worked! I can then read the diskette back, write on it, etc... And of course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive setting that would prevent it to write at high density but let it do at low density? At high density, have you taken a good look at pin 2 of the floppy interface? Have you checked to see if pin 2 is configured (via jumpers) as density select?Various drives have different jumperings for pins 2 and 34 (and sometimes 4). For example, I deal with some Japanese CNC gear that uses pin 2 for disk change and pin 34 for read (and pin 4 for in use. --Chuck If formatting an already formatted disk, the format program will notlet you format a different density.Do note what I said earlier. Just formatting and writing to a 360K ona 1.2M drive can in some cases make it unusable on a 360K drive.The 1.2M drive does not erase the full width of a 360K track.When attempting to read on a 360K drive, there will be too much noisefrom the older track.If you are really interested in creating 360K disk, you must have a 360Kdrive.Dwight
Re: 5.25 floppies that read but don't write
On Thu, Aug 20, 2015 at 9:01 PM, dwight dkel...@hotmail.com wrote: If you are really interested in creating 360K disk, you must have a 360Kdrive. And beyond that, sometimes trying to format or write to a 360K (48 TPI) disk in a 1.2M (96 TPI) drive does appear to work, and may even appear to read reliably on the same drive, but it's *NEVER* going to be reliable to read it on an actual 48 TPI drive. The best case result is if you use a 96 TPI drive with a floppy that has NEVER been written (even at the factory), and format it and write at 48 TPI, that actually may read reliably on 48 TPI drives, because it doesn't have remnants of normal-width 48 TPI tracks. However, it's still not recommended for obvious reasons. Some people have claimed that they've been able to achieve the same effect by degaussing the floppy first, but when I experimented with that I found that even a supposedly high-power degaussing coil was pretty marginal for actually erasing floppy disks. It definitely would corrupt the data and render it unreadable, but it did NOT yield a truly erased disk.
Re: 5.25 floppies that read but don't write
On 08/20/2015 01:04 PM, Marc Verdiell wrote: So I tried to force formatting in DOS at 360k, and sure enough it worked! I can then read the diskette back, write on it, etc... And of course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive setting that would prevent it to write at high density but let it do at low density? At high density, have you taken a good look at pin 2 of the floppy interface? Have you checked to see if pin 2 is configured (via jumpers) as density select?Various drives have different jumperings for pins 2 and 34 (and sometimes 4). For example, I deal with some Japanese CNC gear that uses pin 2 for disk change and pin 34 for read (and pin 4 for in use. --Chuck
Re: 5.25 floppies that read but don't write
Following Chuck's advice, I scoped out the pin 22 and 24 (write data and write gate) on the floppy, and they looked fine. Then being curious, I managed to figure out what the write wire for Head 0 was. And I discovered I got nice matching writing pulses at 300 kHz (formatting at 360k density), but none at 500 kHz (1.2 Mb density). Results posted here: http://www.vintage-computer.com/vcforum/showthread.php?43874-5-1-4-quot-Flop py-Drive-Not-Reading/page9 So I tried to force formatting in DOS at 360k, and sure enough it worked! I can then read the diskette back, write on it, etc... And of course it failed formatting at 1.2 Mb. But the drive (Chinon FR-506) is a 1.2M one, and reads fine at 1.2M! Any clue? Is there a drive setting that would prevent it to write at high density but let it do at low density? Marc Date: Tue, 18 Aug 2015 21:30:31 -0700 From: ccl...@sydex.com To: cctalk@classiccmp.org Subject: Re: 5.25 floppies that read but don't write On 08/18/2015 09:05 PM, Marc Verdiell wrote: I have connected a 1.2M 5.25 floppy to my computer. After a bit of jumper learning and setting, it's recognized and reads my old DD and HD floppies fine. But for the life of me I cannot write to it. Not under DOS, Win98, or WindowsXP. Which all read fine. Make sure that WRITE GATE goes low (use a logic probe) on pin 24 of the drive while you do your write. If so, your floppy write circuitry has a problem. I.e., it's not the cable. --Chuck
Re: 5.25 floppies that read but don't write
On 08/19/2015 09:10 PM, Fred Cisin wrote: We also had some fun when the purchasing department gave us HD disks! (for use in TRS80 model 1 SD) They would sometimes FORMAT, WRITE, READ, and then minutes later, be blank again. The purchasing agent was in bed with somebody peddling RoyType, and kept substituting those for whatever we ordered. About 4-5 years ago, I got a job of mostly Kaypro (DD) disks--about 400 of them. My heart sank when I saw about a box (10) full of DSHD (3M) floppies were in the lot. Much to my surprise, each of the 20+ year old HD floppies read without errors. So you never know... --Chuck
RE: 5.25 floppies that read but don't write
As a general rule, you should not write to a DD disk with a HD drive. It does not erase the full width of the track. You should only write to DD from a 360K type drive. If you must write using an HD drive, it is recommended that you first completely erase the disk with an external magnetic media eraser. Then when formatting, make sure you select the option to format as a 360K. It still may not read well on a 360K drive but that is life. Dwight Date: Tue, 18 Aug 2015 21:30:31 -0700 From: ccl...@sydex.com To: cctalk@classiccmp.org Subject: Re: 5.25 floppies that read but don't write On 08/18/2015 09:05 PM, Marc Verdiell wrote: I have connected a 1.2M 5.25 floppy to my computer. After a bit of jumper learning and setting, it's recognized and reads my old DD and HD floppies fine. But for the life of me I cannot write to it. Not under DOS, Win98, or WindowsXP. Which all read fine. Make sure that WRITE GATE goes low (use a logic probe) on pin 24 of the drive while you do your write. If so, your floppy write circuitry has a problem. I.e., it's not the cable. --Chuck
RE: 5.25 floppies that read but don't write
Just in case anybody was unaware, . . . VERIFY is NOT a suitable test in this situation. Most beginners assume that VERIFY will re-read the track, and determine whether the write wrote the correct content. IT DOES NOT. VERIFY checks the sector headers and CRCs, and determines whether there is a valid sector or track there, NOT whether the content within the track is what you wanted. In what this particular case appears to be, if the WRITE cricuitry in the drive fails, the computer may state that it wrote to the drive without error, and that VERIFY was successful! But, if the WRITE circuitry fails, the write may fail, without producing any errors (FDC WRITE error codes include seeing WRITE-PROTECT, and a few having to do with not finding the desired sector). Then, VERIFY looks at the same-old content, and declares that Yes, the sector or track is a valid one. What was on the disk before, is what is still on it. We had this with a couple of TRS80 drives. We also had some fun when the purchasing department gave us HD disks! (for use in TRS80 model 1 SD) They would sometimes FORMAT, WRITE, READ, and then minutes later, be blank again. The purchasing agent was in bed with somebody peddling RoyType, and kept substituting those for whatever we ordered.
Re: 5.25 floppies that read but don't write
If reads go fine all around, but nothing will write, I'd be concerned that the write electronics (write amp, etc.) might be defective. But try Will'm D's suggestions, before taking that line, of course.. On Tue, Aug 18, 2015 at 11:12 PM, william degnan billdeg...@gmail.com wrote: Try swapping both a and b drives. Try with only 5 1/4 plugged in to a and then again to b. Makes a difference? Specify make and model of motherboard, drives. Describe cable. Describe ROM settings. Bill Degnan twitter: billdeg vintagecomputer.net I have connected a 1.2M 5.25 floppy to my computer. After a bit of jumper learning and setting, it's recognized and reads my old DD and HD floppies fine. But for the life of me I cannot write to it. Not under DOS, Win98, or WindowsXP. Which all read fine. But can't add a file. It goes through to the motions and makes the noise, heads moves as if everything went fine, but if I take the disk out and put it back in, the file is not there. I can't format either. Fails after a while on the above OS'es with different error messages without the head moving past track 0, suggesting it can't even read back the first track it's trying to format. Formatting from ImageDisk or OmniDisk looks like it works (head goes through the motions over the whole disk). But nothing seems to be written on the disk: neither utility can read the formatting back. Both HD and DD. On the same cable there is a 3.5 A: drive which reads and writes fine. Can't be the controller since it works on the 3.5 drive? The cable maybe? I tried several. Anyone has had this happened ever? Time to bring out the o'scope?
Re: 5.25 floppies that read but don't write
Try swapping both a and b drives. Try with only 5 1/4 plugged in to a and then again to b. Makes a difference? Specify make and model of motherboard, drives. Describe cable. Describe ROM settings. Bill Degnan twitter: billdeg vintagecomputer.net I have connected a 1.2M 5.25 floppy to my computer. After a bit of jumper learning and setting, it's recognized and reads my old DD and HD floppies fine. But for the life of me I cannot write to it. Not under DOS, Win98, or WindowsXP. Which all read fine. But can't add a file. It goes through to the motions and makes the noise, heads moves as if everything went fine, but if I take the disk out and put it back in, the file is not there. I can't format either. Fails after a while on the above OS'es with different error messages without the head moving past track 0, suggesting it can't even read back the first track it's trying to format. Formatting from ImageDisk or OmniDisk looks like it works (head goes through the motions over the whole disk). But nothing seems to be written on the disk: neither utility can read the formatting back. Both HD and DD. On the same cable there is a 3.5 A: drive which reads and writes fine. Can't be the controller since it works on the 3.5 drive? The cable maybe? I tried several. Anyone has had this happened ever? Time to bring out the o'scope?
Re: 5.25 floppies that read but don't write
On 08/18/2015 09:05 PM, Marc Verdiell wrote: I have connected a 1.2M 5.25 floppy to my computer. After a bit of jumper learning and setting, it's recognized and reads my old DD and HD floppies fine. But for the life of me I cannot write to it. Not under DOS, Win98, or WindowsXP. Which all read fine. Make sure that WRITE GATE goes low (use a logic probe) on pin 24 of the drive while you do your write. If so, your floppy write circuitry has a problem. I.e., it's not the cable. --Chuck
