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Atari-Compatible 3.5" Floppy Drives

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raoulduke

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Is there a master list? I'd like to source the cheapest DD drive possible (unless for whatever reason an 1040ST F can somehow take a standard 1.4mb PC floppy drive - which I seriously doubt). Was there compatibility beyond Atari? The interface is 34-pin, which suggests (without research) it could be Shugart; and the 4-pin power adapter is also standard.

Sadly after painstakingly making a VGA cable and InPort Mouse adapter, I've confirmed my floppy drive doesn't work. I get 'target disk unusable' and also that the drive isn't responding. I know nothing about the machine's pedigree so I don't know if someone altered jumpers or something. The drive tries to read both on boot and when I try to format or open the drive. I also tried cleaning the heads with no success.

Maybe I'll try something like this http://eab.abime.net/showthread.php?t=71760 (I don't think I have that drive, though).
 
You can use any PC Drive. Just jumper it to DS0. Just Link the Atari's floppy signals 1:1 to the drive. The lowest Drive select signal of the Atari must be connected to the lowest drive select signal of the drive.
 
incidentally the Atari may very well have used Shugart drives in the beginning (or whenever). Remember the original ST floppy drive was single sided 360k. Later it became double sided 720k. Not sure when, but the TT or something used 1.44 mb drives (I think). There are replacement bare drives on eBay. In fact atarifreak in the UK has at least 1 type (Shugart if I recall), maybe others, or at least had others.

The floppy drive emulators seem to be the way to go though. Not only do you have to find a drive in good condition (granted you may be able to source NOS), but also media. I want to write a book LOL on an Atari ST. I contemplated on the Mac, but nah, I like Ataris better. I probably won't fully entrust the manuscript to any media, except hard copy, but sd/mmc cards rate higher and more reliable then old floppies/drives.

The drive emulators are open source. There's a recent thread from the past week which has the link to most of what you'd need to build one, if you don't want to buy one. In "General" discussions.
 
I appreciate the info. I'm not an ST guy, so I don't want to spend a lot. Are you saying I can put a standard HD FDD drive in place of the DD drive without altering the controller setup (I assumed that wasn't on the drive itself)?
 
Yeah I didn't totally understand the above discussion I'm afraid, so I need some more guidance. But I've also learned some stuff about my particular machine: 1) the problem is somewhere in the drive. Once I removed the drive, the slow boot-time dissipated and it boots immediately from ROM. 2) No drives showed up, so it is also actually detecting the drive and I think it's detecting it as a DD drive because there's an A and B drive that both disappear. 3) It doesn't recognize my HD floppy drive: NEC FD1231M.

This might be the solution: http://www.amigaportal.cz/forum/showthread.php?t=5478, so hopefully Google Translate does well with Czech. So... pin 19 of the IC to pin 10 of the floppy (middle wire in the picture); cut the trace to pin 34 [of floppy, hereafter] and connect it to pin 1; connect pin 34 to TP15 on the board. It looks like that's it. I'm a little concerned about the trace cut, though.
 
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Slow boot with no disk in drive is normal.

The ST does not know if the drive is single or double sided, it just knows its a drive.

What condition is the drive belt in (If it has one).

Seeing "A" and "B" is also normal. TOS will tell you to change the disk in the drive if you click on "B". Allows you to copy disks on a single drive machine.

Can you put any diskette in the drive and try formatting it to 360K? (a 1.44 will usually format).

If that works leave the disk in the drive and re-boot.

For testing you don't need the disk change.
 
Remove the drive cover and see if you can find something like a blown capacitor or loose chip. Find damage, fix same, maybe it will work.

Otherwise you will need a replacement:
1) Get the Epson SMD-380 (or its high density counterpart SMD-300). Double check jumpers and plug it in.
2) Follow one of the online instructions on how to tweak a normal floppy drive into one that is acceptable to the Atari.
3) Buy a replacement drive or kit that is already setup for Atari usage. The only website I found selling these parts is in the UK and charges 15 pounds for the drive and 25 pounds for a HD controller. Shipping would be a killer so maybe you can find a US counterpart.

Check out http://atariage.com/forums/topic/208904-atari-st-floppy-drive-repaired/ for some ideas. Also http://www.atari-forum.com/viewtopic.php?f=74&t=17530

There are other floppy related topics at both websites which might provide more guidance.
 
The Samsung SFD-321B has good OEM documentation on its jumpers and is generally pretty common (Compaq used them on lots of machines).

The single-sided drives used on the 520ST were terrible. I replaced mine with a couple of NEC 720K drives. Are you certain that pin 34 is "Disk changed" and not "Drive Ready"? My NECs have only "READY" and they worked just fine.
 
Chuck,

Drives with no disk change generally work OK most of the time. Its only a problem if you don't re-read the directory after a disk change, and then write to the disk. A duff directory gets written and trashes the disk.
 
I got an SFD-321b Rev WT-05; I did the mod seen here (http://www.atari-wiki.com/index.php/File:Samsung_SFD321B_DS0_Mod_After.jpg) but I still get the error "An error has occurred during format or copy. Target disk may be unusable." with several disks. On the new drive the bar moves slightly and I can hear it trying to format but that's the only difference. The light on the drive and ST seems to blink incessantly. Could this be the mentioned low-power issue rather than an identical problem to the original drive?
 
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g4ugm said:
Drives with no disk change generally work OK most of the time. Its only a problem if you don't re-read the directory after a disk change, and then write to the disk. A duff directory gets written and trashes the disk.
Click to expand...

I dug out my copy of the Bruekmann, English and Gerits "Atari ST Internals", and indeed the 520ST floppy interface doesn't use "READY" nor "DISK CHANGE". Just the basic signals, which figures.

So what could be wrong? Well, the ST uses a WD1772 FDC, which pretty much goes directly to the drive, so no buffering. The drive and side select go through the sound chip, but they don't seem to be the problem.

The Samsung drive is a modern drive, so it draws less current than early drives. Hang a voltmeter on the +5 and see what happens to it when the drive motor switches on. Oh-be sure you're using DD and not HD disks.
 
Well, this is a 1040. It looks like the mega had both those signals. I noticed activity when I inserted a disk. Perhaps I'm wrong.

But the led blinking i noted earlier after a disk is inserted, even after ejected, is quick and 'shallow' - like low intensity; it starts once you insert a disk I think and then persists. I'm thinking that now; I'm not sure if that symptom would not occur if you never inserted a disk but with the new drive I also notice a 'slow boot' to ROM, which makes me think there are read problems. My speculation is perhaps it is something like a misfiring ready light or something. I haven't fully articulated the thought but I think you might be onto something - like the drive expects ready but gets no signal or only gets a constant signal perhaps.

The disks are DD, but I probably have written over the TOS disk I wrote. So, forgetting formatting, to test read I have a few questions since I'm not sure I have a working internal floppy for my PC anymore: 1) is there a disk writing program for classic mac, or less preferably an ST emulator? 2) think windows 7 or 2000 can read ds0 floppy drives - preferably the former?

3) how can I measure the 5v? I'm not that skilled with electrical stuff. On compact macs, I would ground one lead in a port screw home and attach another to a paper clip ina particular port pin. Here I guess I would put the clip into a pin hole on the floppy cable from the board. Is there a convenient way too ground?
 
Wait... that's a link to Disk Copy. Are you saying Disk Copy can just read and write ST formats standard?
 
The standard ST format is close enough to the PC format that disk copy should correctly write out an image. Apple doesn't list which alternate image formats it supports so you may have to try several to find one that works.

PC Exchange should manage to read and write many ST disks if you ever decide to do data transfer. Not all, some Atari ST formats don't even reliably read on the same Atari ST that wrote the disk.

There was an Mac utility that modified ST disk image headers into a form that earlier disk copy versions needed. I can't locate a copy of that. I didn't find any source for a competing classic Mac OS disk imaging program in case you hit problems with disk copy.

Now, if you move to OSX, there are many other disk imaging programs available. Some may be much better suited than disk copy.
 
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