Mystery Floppy Drive???

[DistantStar001]

I recently obtained a mystery 5.25 in floppy drive from JMR Electronics Inc and I was wondering if anyone could tell me what it goes to?  At first I was told that it was some sort of half-hight Shugart floppy clone? but I have my doubts.  It has an internal power supply, The drive itself is double sided, and came with a 34 pin interface ribbon cable that connected to an edge connector inside the case.  From what I can tell this seems to be a longer version of the same kind of cable used to connect the internal floppy drive on my 486.  I've removed it for now, as the cable was damaged about half way through.  Also, the model number is hand written and I'm having some trouble making it out (1505? 1S05? 1805? Something entirely different???).  Below are pictures, and as always, any help is appreciated!

 

[carlsson]

Why can't it be Shugart? For that matter, the IBM PC floppy drive format is not pure Shugart, they were inspired by it but with a few changes IIRC.

 

I have a feeling that one would nicely connect to e.g. a BBC Micro, but also many other systems I can't name but takes an external Shugart floppy drive.

[DragonGrafx-16]

2 minutes ago, carlsson said:

Why can't it be Shugart? For that matter, the IBM PC floppy drive format is not pure Shugart, they were inspired by it but with a few changes IIRC.

 

I have a feeling that one would nicely connect to e.g. a BBC Micro, but also many other systems I can't name but takes an external Shugart floppy drive.

Being that the drive is from the US I would doubt it was for the BBC Micro. Not saying it wouldn't work though.

[DistantStar001]

1 minute ago, carlsson said:

Why can't it be Shugart?

No reason it can't.  I just don't know enough about it to be sure.  I've never seen a drive like it, and the person who sold it to me thought it was an Apple II clone.  The connector is obviously wrong for that, and I'm not aware of any Apple compatible floppy drives that use an internal power supply.

[DistantStar001]

3 minutes ago, DragonGrafx-16 said:

Being that the drive is from the US I would doubt it was for the BBC Micro. Not saying it wouldn't work though.

Same thought, but if I ever get my hands on one it would be great to have a drive ready for it! ? 

[DragonGrafx-16]

5 minutes ago, DistantStar001 said:

No reason it can't.  I just don't know enough about it to be sure.  I've never seen a drive like it, and the person who sold it to me thought it was an Apple II clone.  The connector is obviously wrong for that, and I'm not aware of any Apple compatible floppy drives that use an internal power supply.

It does look to be a PC floppy drive cable though.

[carlsson]

What about various CP/M systems, did those use Shugart drives? S-100 bus? I agree that it isn't a Disk ][ compatible cable.

[+OLD CS1]

What happened to our sense of adventure?  Used to be a day when we would get hold of some unknown piece of hardware and just start connecting it to everything until it worked or let the smoke out.  Fuzzing hardware can be disastrous, yet fun and invigorating, all at the same time!

[carlsson]

While there were a few external 5.25" drives to IBM PC compatibles, those tended to have D-sub connections, either 25 or 37 pin I believe so the cable wouldn't naturally plug into it unless you feed it through the chassis to the motherboard interface. Probably it could be made to work like a PC drive, perhaps some internal jumper that has to be changed.

[carlsson]

Perhaps for something like PMC-80 or LNW-80, but I'm fishing in deep water now.

[+OLD CS1]

What is inside the box?

[+OLD CS1]

From what I can find, during the era JMR made a lot of custom enclosures for all sorts of drives and peripherals, as well as drives for all kinds of different systems.  Can you get the model number off the drive inside, or a picture of it?

[DistantStar001]

3 hours ago, OLD CS1 said:

What is inside the box?

Thankfully not a severed head!

3 hours ago, OLD CS1 said:

From what I can find, during the era JMR made a lot of custom enclosures for all sorts of drives and peripherals, as well as drives for all kinds of different systems.  Can you get the model number off the drive inside, or a picture of it?

Thanks!!! The sad thing is that I took it apart once, and it didn't occur to me to check the drive for markings.  Looks to be a Mitsubishi drive, Model M48530-112U.  I found the manual.  Still don't know what it was meant to be used with since the manual simply refers to a "Host system" and none of the language used is specific to any operating system or hardware.  Honestly, I can't even tell from the manual if it's low or high density?

 

[carlsson]

The M4853 series are 80 track drives (96 tpi), double sided which equals floppy disks of the QD variety (NOT the 1.2 MB HD variety). It is said to work for 5 years or 20000 hours of operation, whichever comes first.

 

http://www.bitsavers.org/pdf/mitsubishi/floppy/M4852_M4853/M4852_M4853_Specifications.pdf

 

Without having full knowledge of what the personal/micro computer market looked like in America in the mid 80's, I strongly think this belongs to some TRS-80 compatible or other CP/M system. If those took generic drives with Shugart interface, there not necessarily need to be a close tie between drive manufacturer and brand or model of computer. Actually both the PMC-80/EACA and the LNW-80 computers are pictured with external drives of the same type and probably those were not unique in any kind.

 

Edit: I had to double check that it really says "whichever comes first". 20000 hours in 5 years is 4000 hours per year, 11 hours per day if you run it in some industrial system that is running 24/7. Essentially if you keep reading or writing on disks continuously for 12 hours per day, all year around it would give up its ghost before the 5 years have passed. I would assume it breaks much sooner than so with that kind of usage. It also means that after 5 years, you can't reliably expect the drive to work any more. We're more than 35 years past its manufacture date so any operation would be a bonus according to the manufacturer.

Edited August 20, 2021 by carlsson

[+OLD CS1]

21 minutes ago, carlsson said:

We're more than 35 years past its manufacture date so any operation would be a bonus according to the manufacturer.

Pretty much every device we use here is past its life expectancy.  I know I am

[DistantStar001]

25 minutes ago, carlsson said:

Without having full knowledge of what the personal/micro computer market looked like in America in the mid 80's, I strongly think this belongs to some TRS-80 compatible or other CP/M system. If those took generic drives with Shugart interface, there not necessarily need to be a close tie between drive manufacturer and brand or model of computer. Actually both the PMC-80/EACA and the LNW-80 computers are pictured with external drives of the same type and probably those were not unique in any kind.

Interesting.  But as far as I know, the TRS-80 line only used single sided drives?  Maybe with a ROM update?  Or maybe the Model IV?  Still, the TRS-80s I've seen all used edge connectors for the floppy, and this has a pin connector?  

 

A CP/M system is possible.  It came to my local recycler with a fully functional Exidy Sorcerer (tragically out of my price range).  However, there was no port or attachment on the Exidy to indicate that it connected to that particular computer.  Still, if the original owner had started out with one CP/M machine, then it makes sense that they might have upgraded to another.

[glurk]

I actually have a Tandon TM100-1A drive that came out of a Percom AT-88-A1 (Atari) enclosure, where I replaced the controller board on it with a Tandy one, and it's now inside my TRS-80 Model III - and working fine.

 

The drive mechs are not made for any specific computer.  That's a Mitsu drive in a JMR enclosure...  Assuming that the enclosure is just a power supply, and a drive, then it should work with anything you plug it into, assuming the machine has a DOS that supports it.

 

The TRS-80's support DSDD just fine, but you need the right DOS, and some special cable mods.  Same with the CoCo's OS-9.  And I bet that would plug right into my Percom as an external drive as well, with Sparta, or MyDOS, or whatever.

 

All I'm saying, really, is that it "doesn't have to" be made for any specific system.  It's just an external 5 1/4" drive....  I'd like to have that one myself, LOL.  That type of half-height enclosure is rare and hard-to-find!

 

[Turbo-Torch]

Quote

Interesting.  But as far as I know, the TRS-80 line only used single sided drives?  Maybe with a ROM update?  Or maybe the Model IV?  Still, the TRS-80s I've seen all used edge connectors for the floppy, and this has a pin connector?  

 

Nope.  That drive would work fine in my Model III.  My Model III's controller card will even support 8" and 3.5" drives both SS or DS, 4 total.

I've had Texas Peripherals, Tandons, Teacs and others hooked to my Model III...internal and external.  That drive would just need a female edge connector on the cable to plug into the external drive port.  

 

I'm not sure why all the talk about Shugart?  Outside of being a rare 80 track, that's just a typical 1980s floppy drive that could be used in any number of CPM systems, TRS-80s, IBMs and a million clones.  The 80 Mirco magazines were full of ads for those and listed all the systems they were available for. 

If I can find an ad, I'll scan it and post it.   

[+OLD CS1]

Not often I see a head-loading floppy drive.  At least, it shows in the manual but I am not certain I see it in the photo of the drive.