Kishy loves replies to read and reply to
My understanding is as follows:
48tpi DD = Double Density, 160KB/180KB/320KB/360KB
96tpi HD = High Density, 1.2MB
However, HD disks won't allways format correctly if formated as DD disks. In fact, most HD disks I have tried reported loads of bad sectors when I tried it. In the same manner, DD disks can't be formated as HD disks.
About your 96tpi DD disks, I think those may be a hybrid, capable of being formated as either HD or DD. Do those disks give you errors when you try to read them?
the format command you should be using goes as follows:
The "Cross-formatting" (HD to DD or DD to HD) kind of makes sense...the physical media, at least as I see it, doesn't correspond to the locations that the drive will try to access (yay or nay?)
The 96tpi DD disk (it looked like I had two but it was because they both had the same brand label on them, but only one is actually 96tpi DD) doesn't seem to want to work. I haven't tried putting anything on it and then trying to take it off, but logic says that would probably work fine because the same drive is doing the writing and reading, and it would only write to areas that it thinks are good.
Depending on what format I try to force on it, the "bad sectors" as detected by Scandisk will vary, but there are ALWAYS a lot of them. It's obvious that either a) the disk is actually damaged, b) the wrong format is being used resulting in those "fake" bad sectors or some sort of mix of both.
I'm not sure I want to try an unconditional format...if it is refusing to do it, wouldn't that possibly result in drive damage if the drive was instructed to, for example, seek to a location it doesn't know how to seek to (for example smash the r/w heads into something internally)? Obviously that's less catastrophic for a floppy drive which moves slowly compared to a hard drive, but still not good.
Your drive and bios may not support it. Unfortunately, a relatively uncommon format from a decade earlier will fall prey to the relentless effort to save fractions of a penny.
There were some 5.25" drives that did support both the 1.2 MB and 720kB formats with the ability to easily shift tpi and rpm as needed for disks. Specialized drivers would probably also be needed. I hope someone else can recommend methods that work.
I hesitate to point to the following web page since if the author is a poster here, the author is much better suited to answer questions:
http://www.oldskool.org/disk2fdi/525HDMOD.htm
But if you are lucky, you might be able to modify your drive to read the quad-density disks.
About modifying the drive(s), none of mine are Teac (Toshiba, Fujitsu, Panasonic, Canon/IBM, Chinon) so I'm a bit hesitant to start exploring that quite yet.
As one of the replies after yours states it looks like the format command /f:720 refers exclusively to 3.5" 720k disks, which are far more common it would seem (I actually have some of them, bought them new when I was younger...3 out of the set of 10 still work).
I wonder...I have a few Super-I/O cards, I wonder if the floppy controllers on any of them support 720k 5.25" formatting. Something to investigate in the future...those cards are never as simple to set up as they appear.
The motherboard I am using for this offers the following options for floppy drives in the BIOS:
-360K , 5.25 in.
-1.2M , 5.25 in.
-720K , 3.5 in.
-1.44M, 3.5 in.
(surprisingly, also this one
-2.88M, 3.5 in.
While 77 cylinders is a standard 8" format, there exists an older 5.25" format, recorded at 100 tpi with 77 cylinders. Sometimes, it's called a "Micropolis" format, after the manufacturer that pioneered it, other manufacturers made the drives too. The Tandon TM-100-4M ("M" for Micropolis; a TM-100-4 is a 96 tpi drive) is one such drive. Commodore used the drives briefly.
Mike, forgive me for going into too much detail. I'd assumed that the reason for these discussions was to educate--why would one collect old gear if not to understand it? Maybe I don't understand this collecting business...
Are there any specific advantages to the 5.25" 77 cylinder 100tpi format? I imagine it's useless without hardware support but interesting to know.
Collecting - if I may cut in between you two - can be for many reasons. I don't collect, I use. I have no specific attachment to older computers (and why would I, I was born in 1989) but I find them interesting...I like the challenge they can provide, the way they make me use my brain. I also enjoy dealing with intelligent, friendly, **interested** people when I have an issue or comment of some kind. I went to a computer store that was rumoured to have some older hardware and after the +1 hour trip was told they got rid of it all (but that I could come back in a few days and get some anyway?) rather inconsiderately and the person behind the counter clearly could not care less about the equipment he works on or the people he deals with. How could someone WORK WITH COMPUTERS and clearly hate them so much?
Stay away from the Second Infinite Byte in Windsor, Ontario, Canada - their staff are disrespectful, have a marginal amount of knowledge, and will trash talk you after you leave (as I witnessed when a customer left with their machine).
Chuck - I don't think I got irked by the info. I think I got irked that the implication was that I left out something important to the immediate discussion.
And the broader question is, where do we draw the line on what's an appropriate level of detail? This thread is by far and way more interesting that many of our 'my PC is broken' threads, but at what point does the extra become noise? ClassicCmp is a perfect example of people making this unreadable for the sake of completeness ..
Interesting is generally what I aim for, so it would appear I'm succeeding in that regard.
What's going on here is that 720k 5.25" disks are not a standard format on PCs. The /f:720 option is intended for 3.5" disks, so FORMAT will refuse to make a 5.25" disk at that capacity. There are third-party programs that will format 5.25" 720k disks.
HD drives themselves are perfectly capable of using quad-density floppies, which are just 80-track disks at the DD bit rate. Tandy 2000s aside, QD was used by some CP/M machines as well as Commodore 8050 and 8250 drives.
I figured it might be something about that (720k 3.5" disks), but was hoping maybe the format command could use the same switch for either type. Apparently not.
I've probably missed something in this thread, but are "QD" disks actually different physically, or is it simply the recording method that differs?
