X68000 5.25" Floppy Drive: Unveiled!

[NFG]

Someone recently asked me for a lot of info on the X68000 drive, so I opened one up and took a couple of quick snaps:

http://nfggames.com/games/X68k/X68Drive1.jpg
http://nfggames.com/games/X68k/X68Drive2.jpg

The ejection mechanism is pretty cool.  It appears to operate more or less independantly of the drive itself.  If you follow along on image one...

1. The disk is inserted, and moves the CLAMP LOCK DISENGAGE out of the way.  This frees the clamp drive assembly to move.

2. The disk interrupts the DISK LOADED SENSOR, signalling that the disk is firmly inserted.  At this point the disk could not be easily extracted from the drive, so it's assumed it's safe to clamp.

3. (Image 2) The motor engages, driving a wheel which forces the clamp assembly towards the rear of the drive.  This assembly simultaneously hub-clamps the drive and lowers the drive head.  Two sensors indicate the assembly's movement: CLAMP LAUNCHED (img 1) and CLAMP LOCKED (img 2).

4. Once the CLAMP LOCKED sensor is tripped, the drive spins up and data reading begins.

It's a very elegant system, IMO.

[Computolio]

     It turns out that Canon made the drive. It's a heavily modified version of the MD 5501 half-height drive, and seems to have mostly been used in early Compaq portables. They don't even seem to be too hard to find.

     Solving the problem of dying drives might have just got easier.

[ken_cinder]

Not quite the same model on that Ebay auction (K-61435 line), but nothing saying parts won't work.

The K-61432-16 and K-61432-61 models look closer, though don't seem as easy to find......and some places want over $200 for one drive!

[Computolio]

     Those prices are from resellers aiming to gank money off of corporate buyers and can be safely ignored, especially since they also charge hilarious amounts for equipment that is truly easy to find.

     I've scanned in some (gigantic) pictures of the specimen I found:

     pic1
     pic2
     pic3

     It does seem a little bit different from all of the drives shown online so far, which is interesting.

[NFG]

That's unquestionably from the same family of drives.  Seems to be a newer model, as it has fewer chips.  I'd be willing to bet it'd work, once you get around the data connector being on the wrong side (The first model X68000 was like that, the rest were reversed).

Interesting that it has empty holes on the PCB for the drive select pins.  Also interesting that it has some leftover mount holes for some of the clamp assembly that was used on the X68, but on this.

[l_oliveira]

Hm ... The drive is built on Fujitsu parts ...
Is the pinout of the MFM bus custom ?

[Computolio]

    Fujitsu parts? Where?

    Also the bus used for standard floppy drives of this type is called the "shurgart bus". On the X68000 it is slightly modified to allow for better disk insert detection and the auto-eject mechanism.

[l_oliveira]

Prefix MBxxxxx for Fujitsu ICs.  The ones on the original X68000 drive even bear the Fujitsu logo.
LB is prefix for Sanyo parts. Which I believe to be the heads stepper motor activator high current driver.

The newer PC drive has a MB88001 Fujitsu chip, an Sony CXA1073Q and some Rohm chip as actuator for the head stepper motor...

So the name of the bus is Shugart ? Interesting. Does it have anything to do with the slightly newer bus used on MFM drives of the PC-XT era ??

[Computolio]

    As I understand, MFM/RLL/ESDI/whatever that ugly horrible ancient thing with the two cables is called is a sort-of extended version of the floppy bus. The 34-pin floppy-style cable is used for controlling the drive heads and the extra 20-pin cable is used for data transmission.