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The 8" (eight inch) floppy drive & disk thread


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Since there're a few of us here who have 8" floppy disks and/or drives, or who are interested in them, starting a thread to share info seemed like it would probably be a good idea.  Here it is :D

 

Starting off: I recently came by a pair of Mitsubishi M2896-63-O2U half-height drives that had been pulled from an ex-Federal government system.  Both are clean, have working eject mechanisms, and look to be in overall good condition with virtually no dust in them.  Their manufacturer labels identify them as Revision J drives, with dates of manufacture of 03/1988 and 04/1988.  This is pretty late in the game for 8" drives, so I'm hopeful that they're functional, particularly given how low-use they look to be.

 

First thing to do is establish functionality.  An 8" floppy disk Shugart interface adapter 50 pin to 34 pin PC compatible has been ordered from eBay; it should get here from France in a week or two.  The FDADAP floppy disk adapter from dbit.com was being considered first: it adds a two-digit LED display for the current track number and support for DEC RX50 drives.  However, that would require making 50-pin cables in order to use it.  The eBay adapter can be ordered with a Shugart-compatible card edge connector, so plugs straight onto the drive with no need for additional cabling.  Just add a regular 34-pin floppy cable and it's ready to go, which seemed like a simpler route for starting out.

 

One thing I will need to pick up is a way to get power into the drive.  It uses +5VDC, -5VDC, and +24VDC.  As a result, there aren't many off-the-shelf options for doing this, but the FDDC DC-DC converter for 8" floppy drives (also from dbit.com) looks like a strong contender.  It's $80, however.  It's also out of stock, so won't be happening for a while.

 

First thing that I'm planning on doing with it (once everything is up and running) is connecting it to the Kryoflux and seeing if I can pull anything from a couple of dozen 8" disks I have laying around.  Their labels hint at their contents, but it'll be interesting to see what - if anything - can be recovered.

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Nice find.  Half height and they don't need 120VAC to drive the main motor. 

Mine are old Shugart 800-2.  Full height, built like a tank and 120VAC for the motor that turns the disk.  There's no starting the motor when the drive wants reading.  You put a disk in and the drive starts turning it.

 

When I get them hooked up to the ATR8000 we'll see if they can still read the old disks I have.

 

 

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2 hours ago, kenp said:

Nice find.  Half height and they don't need 120VAC to drive the main motor. 

Thank you, and I can't describe how thrilled I was when I looked at them and realised that they didn't require mains voltage.  I wouldn't toss out a drive that required it, but this makes things much simpler.

2 hours ago, kenp said:

Mine are old Shugart 800-2.  Full height, built like a tank and 120VAC for the motor that turns the disk.  There's no starting the motor when the drive wants reading.  You put a disk in and the drive starts turning it.

If these are the ones I'm thinking of, they are total tanks.  Only ever used them a handful of times with IMSAI 8080s and the like at retrocomputing events, but was impressed with just how solid they are - and the sounds that they make.

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9 hours ago, x=usr(1536) said:

Thank you, and I can't describe how thrilled I was when I looked at them and realised that they didn't require mains voltage.  I wouldn't toss out a drive that required it, but this makes things much simpler.

If these are the ones I'm thinking of, they are total tanks.  Only ever used them a handful of times with IMSAI 8080s and the like at retrocomputing events, but was impressed with just how solid they are - and the sounds that they make.

Funny you should mention the IMSAI.  That was what I bought my Shugarts for originally.  I don't have the IMSAI any longer. 

There's a dealer of vintage hardware in town and he lists an IMSAI 8080, all tricked out and with two 8" floppy drives, for $25,000.  (Maybe if I win the Powerball. 🙂

Edited by kenp
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Pardon my language but   ...   Well, bugger me.   You're not going to believe it because I don't believe it.  So many details lost in the annals of time.

 

I finally found how I adapted the 50 pin connectors on the 8" floppy drives to the 34 pin cables and connectors on the ATR8000 and it was not entirely a happy thing to find.

 

I wanted to confirm the 50 pin connectors on the backs of the 8 inch drive cabinets so I pulled one out of the drawers they were stored in.  I figured while it was out I'd have a good look inside and see what sort of shape things were in.  Sitting there, hanging onto the 50 pin card edge on the drive on one side and connected via a 50 pin card edge connector to the 50 pin cable leading to the 50 pin IDC connector on the back of the cabinet was a little adapter.  Well, what the heck was an adapter doing going from a 50 pin card edge to a 50 pin card edge connector thence on to a 50 pin IDC connector.  So, I unplugged the cable from the back of the cabinet to the adapter and the dang thing has a 34 pin card edge connector.  IT'S AN ADAPTER GOING FROM A 50 PIN CARD EDGE CONNECTOR TO A 34 PIN CARD EDGE. 

 

When I checked the other drive I found another adapter in the other drive. And you'll never guess the company name of the danged thing.  Yup, Software Publishers, Inc.  It's an adapter from the same folks who made the ATR8000.  I must have ordered or bought the adapters about the same time as I bought the ATR8000, buried them inside the 8" drive cabinets and then just plugged the 34 pin cables in at one end of the 50 pin IDC connector on the back of the cabinets.  (That would explain the little green paper dot on one end of the 50 pin connector, right?  That's where pin 1 of the 34 pin connector would go, at that end.)

 

Here's where it gets sad and I show how I can make the most stupid mistakes.  When I unpacked everything I found a really long 34 pin cable with an assortment of 34 pin card edge and IDC connectors.  I figured this must have been something I was working on to make the connections between the drives but not completed because it didn't have any fancy adapter on it.  SO I CUT THE DANGED THING SHORT enough to handle the 5.25" drives and put the rest aside.  Now I have to find the parts and flat cable to re-do the long cable so I can re-attach the 8" drives.  Slightly easier than mucking about with 50 pin connectors (they're really a nuisance to get these days) and having to hand wire an adapter but, Dang, I can make things hard on myself at times.

 

One good bit of news, if it hasn't been done and recorded somewhere already, is to trace and set out a record of the connections between the 50 and 34 pin connections on the genuine Software Publishers, Inc. adapter.  No more speculation or guessing.  It will be known how the ATR8000 folks did it.

 

edit:  I found the piece of cable I'd cut off from the bit needed for the 5.25" drives and it wasn't a complete cable.  There weren't enough of the IDC connectors to connect to the 2 8" drives.  I feel a little better that I didn't ruin a completely good thing in that cable and the piece left is long enough to make the new cable after I find the needed connectors.

 

But first, I have to tidy tings up here and take a nap.

Edited by kenp
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1 hour ago, kenp said:

Pardon my language but   ...   Well, bugger me.   You're not going to believe it because I don't believe it.  So many details lost in the annals of time.

 

I finally found how I adapted the 50 pin connectors on the 8" floppy drives to the 34 pin cables and connectors on the ATR8000 and it was not entirely a happy thing to find.

Having read through the rest of the post, I understand exactly what you mean by that.  Still, it's a good find overall.

1 hour ago, kenp said:

IT'S AN ADAPTER GOING FROM A 50 PIN CARD EDGE CONNECTOR TO A 34 PIN CARD EDGE. 

Full credit for that cable run using a wide variety of connectors in the process ;)

1 hour ago, kenp said:

Now I have to find the parts and flat cable to re-do the long cable so I can re-attach the 8" drives.

Or skip rebuilding the cable and just use a card edge to 34-pin adapter, if feasible.  At least 34-pin cables are still relatively easy to come by.

1 hour ago, kenp said:

Slightly easier than mucking about with 50 pin connectors (they're really a nuisance to get these days) and having to hand wire an adapter but, Dang, I can make things hard on myself at times.

Totally understood.  FWIW, Amazon has a 5-pack of 50 Pins IDC 2.54mm Card Edge Connectors for 1.27mm Flat Ribbon Cable for $15.95 right now.  Even though I've decided to not build my own cables (if possible) for this round of getting things running, I did order a set just to have them on hand.

1 hour ago, kenp said:

One good bit of news, if it hasn't been done and recorded somewhere already, is to trace and set out a record of the connections between the 50 and 34 pin connections on the genuine Software Publishers, Inc. adapter.  No more speculation or guessing.  It will be known how the ATR8000 folks did it.

That would be awesome to have.  The more documentation the better.

 

BTW, you may want to check out the following thread if you haven't already:

 

Incidentally, that thread references a link on classiccmp.org that's now dead.  Fortunately, archive.org has it indexed:

 

https://web.archive.org/web/20161024034200/https://classiccmp.org/dunfield/img54306/cnct.htm

 

Some really good info there on the nitty-gritty of creating 50-to-34-pin interfaces (including cables).

 

1 hour ago, kenp said:

edit:  I found the piece of cable I'd cut off from the bit needed for the 5.25" drives and it wasn't a complete cable.  There weren't enough of the IDC connectors to connect to the 2 8" drives.  I feel a little better that I didn't ruin a completely good thing in that cable and the piece left is long enough to make the new cable after I find the needed connectors.

Phew :D  That's one bullet dodged...

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Quick addition regarding the eBay 50-to-34-pin adapter boards from user aberco: there are some excellent diagrams in that auction giving a good overview of the connections that need to be made to adapt a 50-pin edge connector to a 34-pin IDC floppy connector.

 

They're attached to this post for reference; if the person (aberco) holding the auction wants them removed, I'll be happy to do so.

654864411_Shugartinterface50pinto34pinadapter.thumb.png.31ec5d9db674ef0b2842e7233eb4a5d2.png296781068_Pinoutofthecontrolsignalsjumperblock.thumb.png.20fd64393266cf54dde8852093415d2a.png1125219604_50pinto34pinjumpersettings.thumb.png.6bd8fcf6cd7975c1f864d11b3f5597c4.png2144549837_50pinto34pinPCBschematic.thumb.png.c93ddc940dd14e19cccfc436ebeea641.png

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27 minutes ago, x=usr(1536) said:

Quick addition regarding the eBay 50-to-34-pin adapter boards from user aberco: there are some excellent diagrams in that auction giving a good overview of the connections that need to be made to adapt a 50-pin edge connector to a 34-pin IDC floppy connector.

 

They're attached to this post for reference; if the person (aberco) holding the auction wants them removed, I'll be happy to do so.

654864411_Shugartinterface50pinto34pinadapter.thumb.png.31ec5d9db674ef0b2842e7233eb4a5d2.png296781068_Pinoutofthecontrolsignalsjumperblock.thumb.png.20fd64393266cf54dde8852093415d2a.png1125219604_50pinto34pinjumpersettings.thumb.png.6bd8fcf6cd7975c1f864d11b3f5597c4.png2144549837_50pinto34pinPCBschematic.thumb.png.c93ddc940dd14e19cccfc436ebeea641.png

I've seen this but too old to figure all the jumpers.  (Well, that's my story and I'm sticking to it.)  But being troubled by OCD I'd always be afraid I'd set a jumper wrong.  Now I know how to set all the jumpers to make it act like exactly like the SWP adapter. 

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59 minutes ago, x=usr(1536) said:

Having read through the rest of the post, I understand exactly what you mean by that.  Still, it's a good find overall.

Full credit for that cable run using a wide variety of connectors in the process ;)

Or skip rebuilding the cable and just use a card edge to 34-pin adapter, if feasible.  At least 34-pin cables are still relatively easy to come by.

Totally understood.  FWIW, Amazon has a 5-pack of 50 Pins IDC 2.54mm Card Edge Connectors for 1.27mm Flat Ribbon Cable for $15.95 right now.  Even though I've decided to not build my own cables (if possible) for this round of getting things running, I did order a set just to have them on hand.

That would be awesome to have.  The more documentation the better.

 

BTW, you may want to check out the following thread if you haven't already:

 

Incidentally, that thread references a link on classiccmp.org that's now dead.  Fortunately, archive.org has it indexed:

 

https://web.archive.org/web/20161024034200/https://classiccmp.org/dunfield/img54306/cnct.htm

 

Some really good info there on the nitty-gritty of creating 50-to-34-pin interfaces (including cables).

 

Phew :D  That's one bullet dodged...

I found a place in town that looks to be carrying the 34 pin card edge and IDC connectors.  I just need to figure out a jig to press them together.  Maybe I'll find something in the old toolbox.  (I've got the regular toolbox and and old toolbox full of stuff other people discarded.  I might have a portable vice in there.)  It was easier back in the day.  I actually worked at an industrial electronics wholesaler and we had all the bits, bobs and tools in the shop.  Anyway, what I'll be putting together will be a single cable about 6 foot long that will chain the ATR8000, the two 5.25 drives and the two 8" drives all at once.  They're all labelled for such a config.  The 5.25 as drives 1 and 2 and the 8" drives as 3 and 4 or A, B, C  and D for CP/M.

 

I'm still flabbergasted by finding those adapters already buried in the drives.  In hindsight, it makes perfect sense and, as I said, explains why there are little green paper dots on the cases near the 50 pin IDC connectors.

 

I did see that article about creating an adapter so I must have found it through yet another link.  Really going old school by cannibalizing another discarded interface card and cutting it down to create the adapter.

 

A side note to this is that while I had the drive cases open I checked to see about the termination resistors.  The 5.25" drives have removable resistor networks and you just put one in on the last drive in the chain.  These old 8" drives seem to have the termination resistors soldered straight in place.

 

It's all getting so close.  Soon I'll be able to post a trophy pic when I get it all running again.  🙂

 

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Interesting project, can't wait to hear how it turns out.

 

I have 2 half height drives, one appears new and the other is definitely new (still sealed in the antistatic bag).

I have a large dual drive Bernoulli box and I think I may be able to replace those Bernoulli drives with the 8" floppy drives.  There should also be enough room left over for a power supply.  At one point I think I found the specs for a Meanwell PS that did 5, -5 and 24.

 

My Model III has an aftermarket controller that supports 8" drives, so my goal is to set them up as externals and paint the case battleship gray to match.

 

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Here's the old 1982 Software Publishers, Inc 50 pin to 34 pin drive adapter connections.

These were taken from an actual adapter that I had in my own hand and recently found in my old 8" floppy drives from my old Atari days.

 

(Tried doing it as a paste in line but lost all the formatting. 

I mean, yeah, it's just spaces but they make it more clear. 

So I'll try making it a file attachment and see how that works out. )

swp-50-34-adapter.txt

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5 hours ago, kenp said:

So I'll try making it a file attachment and see how that works out.

Looks fine.  It appears to basically be the text version of the schematic above, just minus the jumper blocks.

 

One thing I did notice: on the 50-pin Shugart connector, the text version doesn't implement the TG43 line on pin 2, double-sided support on pin 10, motor interlock on pin 16, or the disk change line on pin 12 of the 50-pin connector.  Not sure if these are necessary for ATR8000 support (or if they're not supported by the ATR8000), but they'd be easy enough to add in if needed.

6 hours ago, Turbo-Torch said:

At one point I think I found the specs for a Meanwell PS that did 5, -5 and 24.

My guess is that it's probably an AT power supply, but if you track that down I'd be very interested in knowing which one it is, particularly if it can handle power consumption over 200W.  I'll probably end up going with the dbit.com power boards, but if they're unobtainium having an alternative would be a huge plus.

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5 hours ago, x=usr(1536) said:

Looks fine.  It appears to basically be the text version of the schematic above, just minus the jumper blocks.

 

One thing I did notice: on the 50-pin Shugart connector, the text version doesn't implement the TG43 line on pin 2, double-sided support on pin 10, motor interlock on pin 16, or the disk change line on pin 12 of the 50-pin connector.  Not sure if these are necessary for ATR8000 support (or if they're not supported by the ATR8000), but they'd be easy enough to add in if needed.

I used these adapters and 8" drives just as they were.  BUT the drives were even older than the ATR8000 and weren't double sided.  There is a Side Select pin at 14 and the ATR8000 knows how to handle double sided 5.25" drives.  Yup, no jumpers on these babies just put them in and cross your fingers.  But they were designed for the drives at the time.  I'm sure newer drives have more options.

 

There's no motor control on the OLD 8" drives.  You put a disk in the drive and it starts spinning.  The 5.25" drives seem to have jumpers that are able to link the motor to the drive select so that when that drive is selected the motor will start.

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Correction.  When you turn the power on the motor starts.  It doesn't wait for a disk to be inserted.  Man, are they noisy.  Of course, 40 years in a drawer likely hasn't helped that but at least the motors are turning and the disk is spinning which means the belts have survived.

New cable, hooked the ATR8000 to the 34 connection adapter right in the 8" drive cabinet and got the floppy disk seek burp when the ATR8000 was turned on but nothing after that.

AND, I think I'm going to have to set them aside for the moment.  Woke in the middle of the night and started planning the next thing to try, breakout box for connections, finding my old logic probes, maybe getting a Kyroflux, can you build an ATR from a KryoFlux image, setting up an old MS-DOS machine with some diagnostic software, etc.

But sleep is more important.  I've got enough to keep me busy transferring the 5.25" floppies to FujiNet storage and a couple of other concerns that draw attention so they'll go back into storage for a bit.

 

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  • 1 month later...

I just got ahold of an NEC PC-9881K2 dual 8” floppy unit. It was super cheap on Japanese auctions and I felt bad for it, but I probably should have paid more attention to how heavy it is. No idea if the drives need mains power but that make things more complicated if they do, as the power supply has been designed for 100V. 
 

I don’t have any disks for it, but my goal was to use it to dump any 8” disks I came across with the Greaseweazle. I might try to find some blank ones and figure out how to hook it up to the PC-98’s external floppy interface. 

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On 3/5/2023 at 6:11 PM, leaded solder said:

I just got ahold of an NEC PC-9881K2 dual 8” floppy unit. It was super cheap on Japanese auctions and I felt bad for it, but I probably should have paid more attention to how heavy it is. No idea if the drives need mains power but that make things more complicated if they do, as the power supply has been designed for 100V.

Where this gets tricky is if the drive was designed to accept AC mains power plus whatever DC voltages it needs, or if the computer supplies it with DC only.  There's no good way to know without finding the specs.  Going out on a limb, the dual-drive unit is probably handling the power conversion internally - but there's no guarantee of that.

On 3/5/2023 at 6:11 PM, leaded solder said:

I don’t have any disks for it, but my goal was to use it to dump any 8” disks I came across with the Greaseweazle. I might try to find some blank ones and figure out how to hook it up to the PC-98’s external floppy interface. 

It's possibly the 50-pin Shugart standard, or a derivative thereof.  If so, you may be able to run it straight to the Greaseweazle via a 50-to-34-pin adapter.

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Be aware that there are some versions of NEC PCs which use 8" drives that don't conform to the normal connector standard. Adrian's Digital Basement had one a few months ago, and it ran MS-DOS. (I have actually had one of those for a while, and I was not happy to hear that I probably won't be able to use it with my old Catweasel.) Fortunately I have a few Model II/12/16 computers, and an external Model II drive chassis. I have a box of floppies (some RSX-11!) that I've been wanting to read for years.

Edited by Bruce Tomlin
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10 hours ago, Bruce Tomlin said:

Be aware that there are some versions of NEC PCs which use 8" drives that don't conform to the normal connector standard. Adrian's Digital Basement had one a few months ago, and it ran MS-DOS.

Thanks for the reminder; I'd completely forgotten about those.  For reference:

 

 

 

 

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  • 3 weeks later...

Oh hey look, a thread on these chunking idiots and mention of NEC drives! Here's a third of what I have scattered around my house:
20230329_123315.thumb.jpg.74ed3e27d45a16a9bdcd8d5f331f8c94.jpg


I've been pretty big into NEC-related gear for the past year and a half or so, mainly focusing on earlier machines. As y'all have posted with Leaded's mention of the 9811K/the NEC N5200-05 (APC), those NEC FD1165s are beefy. They do adhere to a relatively normal Shugart standard but require TG43 signal control, the simple adapter board described above doesn't work amazingly well for writing these disks out (I have one of the ones you can buy off Tindie for hooking 5.25"s to my Greaseweazle). You'll preferably want something like the fdadap to get any serious jobs done. On the 9801 side, you have a "1MB Floppy Drive" connector with a pinout that follows the picture below (From the PC-9801M User's Manual):
20230329_124314.thumb.jpg.737f7827c4e2badd9def48a78e61f578.jpg

Regarding power, drives (as-mentioned in the link above) just need +24VDC and +5VDC to function. On original PC-9801s, and only original PC-9801s, there's a SRCN6A16-7 connector (Female on the PC, Male on the FDD) built onto the power supply which carries what you need. I can't find my original PC98 manual to save my life, but whenever I do I'll come back and add what the pinout is:
1808338276_srcnfunny.thumb.png.c8d416112440206807c5f89a1cc90109.png

With the PC-8811 (8" FDD for the PC-8801) and all later 9811 models (9811K, 9811N, 98H81, any third-party drive, etc.) you'll have an internal box that does your AC-DC conversion. I just plug it into one of the daisychain ports on the back of whatever 9801 I'm using at the time, if you wanted to replace it with a more modern supply then that wouldn't be too tough as you have a ton of room. Same as the SRCN, whenever I come back with my manual I'll get the color code for what wire is what voltage down. I don't have any good photos but you can see it along the bottom here:
big.thumb.png.cb1918658f2670501c2ecd351313f9c7.png


I'm currently in the process of getting a Greaseweazle setup going as I have a pile of about five games, four PC-9800 system disks, and a whole box-set of Mitsubishi Multi16 system disks and industrial control software which I'd love to get dumped sooner rather than later. Whenever I get it going, I'll try to remember to get it posted here for y'all.

 

On 3/5/2023 at 7:11 PM, leaded solder said:

I might try to find some blank ones and figure out how to hook it up to the PC-98’s external floppy interface. 

Remind me to mail you a box of 8"s with your NABU xD

Edited by BurritoBeans
You *can* do TG43 with the simple board, derp, I just remember the FDADAP being easier because it's automatic.
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