23 replies to this topic

[Tickled_Pink]

I've started testing some of the stuff I have in the garage and the first 520STE I've tried seems to have a faulty floppy drive. It's making a hell of a whining noise when spinning up. It's managed to read one disk but is failing on all the others. I have attached a couple of external Cumana drives and they both do a better job of reading the floppies.

I have a spare 1.44Mb floppy drive and was wondering if it's possible to stick that in there. Even better if it's possible to get it working in both 720K and 1.44Mb floppy modes.

[Official Ninja]

If the floppy supports the way the ST detects disks swaps then the 1.44 drive will work fine as a 720 k drive in the computer.
I don't think it can work as a 1.44 because the system needs to be at least 16 MHz. You would need a Mega STE for that.
As far as floppy drives that work, look for Epson SMD-300 or SMD-340. That is what was used in the Mega computers and Falcons and they just seem to work the best with the Atari's. The SMD-340 was used by HP in several of their computers so they are easy to find on eBay.

[Tickled_Pink]

A couple of the STEs have had upgrades fitted but I'm not 100% sure what. Did the Ajax chip ever make it to the non-Mega STE range?

The drive I have to hand is the Sony MPF920. I did find a list of compatible drives and it listed the Sony MPF520. It looked like an old list, though.

[wood_jl]

Unfortunately, the Epson SMD-series are really kind of pieces of junk.  I have 2 bad SMD-380s sitting right here, and I have had one other.

The only way to get a new one (I think) is from Best Electronics, for $75 (or more?) plus shipping.  Unfortunately, when you purchase a used one, it's likely to be a short-lived piece of junk, too.  After all, if it were in a nice (nice = unused or used very little) machine to begin with, they probably wouldn't have been parting that machine in the first place.  Trust me, you won't want to trust a "good used" one.

There are places selling replacement drives (square bezel) on Ebay.  Most seem to be in the U.K.

.....Ebay link....

These places will not respond to questions about their mods to the drive.  I suppose they regard it as a trade secret or something.  I just wanted to know if it was indeed modified, and if it needs to be, like the Sony 920MPF does for Amiga.  I think the Amiga needs similar mods, but there is likely some correlation.  I don't know if Amiga does the same non-standard (or so I am told) disk change detection.  Perhaps that is another mod?  But this thread from the English Amiga board, on the topic of the 920MPF Sony drive may be of some value......

http://eab.abime.net...ead.php?t=43265


I've been using the HxC SD-card floppy emulator so much, that the burden of maintaining  working actual floppies has somewhat diminished.  I have a couple replacement drives Ebay drives. (I also have some new 920 MPFs) I slid the sheet metal covers off just to look, and I did not observe any modifications.  I was pretty much expecting to see something similar to what's done to the Sony drive in the above Amiga thread.  I plugged one in and booted.  But it seems I think there was some little quirk I can't remember, but since I was so thrilled with the floppy emulator I lost interest.  I'm going to have to dig one up and try again.  You have to cut out the case a little bit to get these to work, but it's not a whole lot of cutting.  It should, of course, be done neatly!

[Tickled_Pink]

Well, I've just taken a look and the drive I have won't work with it. However, I suspect that the noise is a slipping belt. The spindle seems to be turning much slower than I'd normally expect a floppy drive to turn. I'll open up one of the others to compare. Drive belts in that link are about a fiver inc. postage.

[Tickled_Pink]

Well ... bugger me. This drive doesn't have a belt. The spindle is turned by magnets. Might be one or more of the coils aren't working properly. On some disks, which can be read from another ST, the spindle fails to turn at all until the drive is tipped to its side. Without the circuit board containing the coils in place, the spindle can be spun freely.

So it looks like a new drive is needed.

[krupkaj]

Check Techie Alison's web. There are nice instructions how to modify Sony MFP-920 drive for using with the ST.
http://www.logicsays.com/atari/

Edited by krupkaj, Sun Mar 4, 2012 9:27 AM.

[Tenorman]

wood_jl, on Sun Mar 4, 2012 6:33 AM, said:

There are places selling replacement drives (square bezel) on Ebay.  Most seem to be in the U.K.

.....Ebay link....

These places will not respond to questions about their mods to the drive.  I suppose they regard it as a trade secret or something.  I just wanted to know if it was indeed modified, and if it needs to be, like the Sony 920MPF does for Amiga.

I bought one of the floppy drives that atarifreakz / st freakz sells last year and I've never had any issues with it.  It'll take a while to get to the US through customs, but it is certainly one of the more economical ways to get a reliable new replacement drive.

[Official Ninja]

wood_jl, on Sun Mar 4, 2012 6:33 AM, said:

Unfortunately, the Epson SMD-series are really kind of pieces of junk.  I have 2 bad SMD-380s sitting right here, and I have had one other.

I must be lucky. My 2nd Mega STe came with a great working 340 and I got one from ebay for $20 works fantastic.

Still, I know what you mean. These drives are made cheap to be used as OEM parts by manufacturers. All the internal adjustments are factory set.
The motor is glued in place and if the head gets out of alignment, its done. Also the movement is a very small metal gear on a sheet metal spline.
That just cant last forever.

[svenski]

From memory, the drives listed on ebay will work but you'll need to twist the floppy cable to connect  and you'll need to get the dremel out to slightly modify your case to accomodate the standard drive with square eject button.

Wood is right on used, original, drives. Chances are they'll last all of five minutes.

Best are the best   option for an original drive but expensive.

Edited by svenski, Sun Mar 4, 2012 11:00 AM.

[mimo]

I had a stack of Sony drives that I converted for use in the ST. They work great, although 1.44meg was a no go.
Grant-Atari fitted one that I gave him to his STE very nicely buy swapping the original eject button, looked like a genuine drive.
I think I used/gave them all away. I may have a suitable Teak drive knocking about somewhere.

[Tickled_Pink]

Never Mind. Gawd I'm stupid.

Edited by Tickled_Pink, Sun Mar 4, 2012 1:36 PM.

[DarkLord]

Okay, just for the record - an ST does not have to be 16mhz like the Mega STe to use a high density 1.44 meg floppy drive.

However, to use that you'll have to have some sort of mod in place. The 1.44 mech won't work out of the box... You can
follow Ralcool (Sean's) thread on this for lots of info at AtariForum:

http://www.atari-for...hp?f=15&t=18847

just scroll through the list on the first page and pick your topic.

HTHs.

[Official Ninja]

DarkLord, on Sun Mar 4, 2012 2:15 PM, said:

Okay, just for the record - an ST does not have to be 16mhz like the Mega STe to use a high density 1.44 meg floppy drive.

I thought I had read somewhere that it does...  my mistake.

[Tickled_Pink]

Official Ninja, on Sun Mar 4, 2012 2:46 PM, said:

DarkLord, on Sun Mar 4, 2012 2:15 PM, said:

Okay, just for the record - an ST does not have to be 16mhz like the Mega STe to use a high density 1.44 meg floppy drive.

I thought I had read somewhere that it does...  my mistake.

Best Electronics also say that you do. From further reading it appears that some STEs are capable of reading 1.44Mb drives virtually out of the box if they have the right disk controller (WD1772-02-02) and TOS version (2.06?).

[DarkLord]

Hmm, Brad at Best Electronics is usually very accurate.

But, in this case, having hands-on experience with the subject,
I can definitely say its not right. Before I started working on my
PAK project on my STacy, I had added Ralcool's (Sean's) 1.44
high density upgrade to my 2 meg, TOS 1.04, 8mhz STacy. It
worked fine there (after I replaced the WD1772 chip with an
Ajax chip - apparently I had one of the few bad 02-02 chips
that didn't work. Less than 5% are like that - go figure).

Follow Ralcool's thread at Atariforum:

http://www.atari-for...hp?f=15&t=18847

Anyway, here it is in action:

[DarkLord]

Guys, I just did a quick search over at Best Electronics, and while I found some history on the Ajax chip,
which I had read before, I can't find where its stated that a 16mhz ST is needed for a 1.44 drive to work.

Can you post the link or the quote?

Thanks!

[Tickled_Pink]

DarkLord, on Sun Mar 4, 2012 8:12 PM, said:

Guys, I just did a quick search over at Best Electronics, and while I found some history on the Ajax chip,
which I had read before, I can't find where its stated that a 16mhz ST is needed for a 1.44 drive to work.

Can you post the link or the quote?

Thanks!

That's the section I read. I'm probably misremembering and mixing things up with other things I've read.

[DarkLord]

Oh, okay. No problem, I do it *all* the time.

[Official Ninja]

DarkLord, on Mon Mar 5, 2012 1:40 PM, said:

Oh, okay. No problem, I do it *all* the time.

Now I'm wondering where I read that though!
It might have been in some thread over at Atari-forum.
I wouldn't mind getting my stfm to use a 1.44 drive.

[DarkLord]

Official Ninja, on Mon Mar 5, 2012 3:45 PM, said:

I wouldn't mind getting my stfm to use a 1.44 drive.

You should visit Ralcools thread then - I think he has a couple of kits
still left, besides the "all in one" mod that he is currently working on.

Just make sure you read it all and understand what's involved.

Hope you get one!

[Tickled_Pink]

Had a look inside the faulty 520STE for the disk controller. Couldn't find it! At least not where I'd expect it to be. So I thought that Atari may have given it their own part number. So I did a quick search and discovered it's got an Ajax. :-)

BTW, reading through Brad's Ajax info again certainly suggests that you need a 16Mhz clock source to enable HD operation, since that's what Atari were trying to do with the later WD1772 and how they got the Ajax to detect whether it was in a standard ST or a 16Mhz HD enabled machine.

It may well be that the 1772 can be set to read HD disks with just a 8Mhz source.

[DarkLord]

Tickled_Pink, on Wed Mar 7, 2012 11:41 AM, said:

BTW, reading through Brad's Ajax info again certainly suggests that you need a 16Mhz clock source to enable HD operation, since that's what Atari were trying to do with the later WD1772 and how they got the Ajax to detect whether it was in a standard ST or a 16Mhz HD enabled machine.

It may well be that the 1772 can be set to read HD disks with just a 8Mhz source.

Ah-ha! I think the source of the confusion is finally coming to light here...(or perhaps I just didn't catch it the first time).

Anyway, to sum it all up - you most certainly do NOT have to have a 16mhz Atari ST to use a 1.44 meg drive.

What IS needed is a 16mhz *clock* source. The clock source is not the running speed of the CPU!

In fact, there are a couple of places you can get 8mhz, 16mhz, and even 32mhz signals from the Atari ST that
has nothing to do with the CPU.

Is it all clear as mud now?

[Tickled_Pink]

Well, that's pretty much what I'd figured out.  :-)

I think one of the 16mhz sources is at the video shifter.. ?