Early 5.25" 1.2MB / 360KB External Diskette Adapter
5.25" 1.2MB / 360KB External Diskette Adapter
5.25" 360KB External Diskette Adapter  Lacks any POS circuitry.
ADF Sections for 1.2MB Version

Drive Connector Assembly (Plastic "B" Box)

Personal System/2 External Storage Device Cable (HDI-30 / DB37 used with P70/P75)

4869 External & Internal 5.25” Diskette Drive Compatibility and Part Numbers
5.25” FDD or Adapter	8525 All	8530 All	8550 / 8570	8555	8573	8560 / 8580	8565	8580 A21/A31
4869-001
-001 360K	1	1	1	1	1	1	1	1
-001 Adapter	2	2	3/4	4	*	3/4	4	4
1.2MB
4869-002	N/A	N/A	5	5	5	5	5	5
-002 Adapter	N/A	N/A	4	4	4	4	4	4
1.2MB Int FDD	N/A	N/A	N/A	N/A	6	6	6	6
1.2MB Adapter	N/A	N/A	N/A	N/A	4	4	4	4

1 - > 72X6759   (360KB DRIVE)   4-> 15F7996 (ADAPTER/A CARD)
2 - > 72X6757   (ADAPTER)       5-> 15F7993 (1.2MB EXT DRIVE)
3 - > 72X6758** ("B" BOX KIT)   6-> 15F6912 (1.2MB INT DRIVE)

* The 8573 requires an External Storage Device Cable P/N 23F3230, not a 5.25” Diskette Adapter.
** P/N 72X6758 includes: adapter (72X6757), cable, Drive Connector Assembly (Plastic "B" box, 72X6755 ).

Adapter P/N 72X6757 (attachment group) (Pass-through only, it uses the planar FDC).
- This adapter uses an internal cable to attach to the drive connector assembly in the "B" bay.
- This adapter only supports the 360KB 5.25 external diskette drive.
- This adapter is not supported in 8555, 8580 A21 / A31, and 8565. It is not required for the 8573.
- No ADF or software device driver is required with this adapter. It will NOT show up in a slot.
- System Programs and DOS will show the 5.25 external drive as drive "B"

5.25 INCH ADAPTER/A P/N15F7996 (adds another FDC, needs ADF and device drivers)
- A ribbon cable is used only when an internal drive is attached.
- Both the 4869-001 (360KB) and 4869-002 (1.2MB) External 5.25” Drives are supported.
- Option diskette is required for configuration and diagnostics. The adapter will show up in a slot.
- Device driver and installation program are needed to install it.

- Any external or internal drives attached to it will be seen by the system as logically external. The O/S will assign this drive the next available drive designation. For example: if a 115mb hardfile is installed on a model 8580-111 and it is partitioned as C, D, E, F, the next available drive designation is "G. Your external drive will be booted as "G" during post when the device driver is being loaded.

Device drivers
If the device driver is being loaded during POST, the drive letter will be displayed on the screen.
To verify proper installation of the device driver refer to the section in the PS/2 SIM that discusses the "DASDDRVR" patch installation/verification. Replace the filename of "DASDDRVR" with "$FDD5.SYS" and follow the instructions.

David Beem says
   I was sent an early version (883x & 884x date codes on the chips vs. ~903x on my later versions) of the "Diskette Adapter/A" that has a slightly different layout but with the same FRU & FCC ID.
 
   All switch positions are up ("on") on mine; don't know what they do. Y1 & Y2 are reversed from the later board: Y1 = 32MHz, Y2 = 19.2MHz here. They are also the "full-can" crystals. U1 is a NEC 72065C (the diskette controller chip). U2 is a "SED9420", Epson SED9420 CMOS Data Separator for FDD. J1 & J2 are the same as the later board. Outside the identified components there is SMC TTL chips that fill every available position otherwise.

The switches were used during the development of the adapter. A newer release of the card will not have any switches. The card functions exactly the same regardless of the switch settings.

David Beem weighs in with:
  I have the driver for this board (4869drve.exe). Interesting to note the 34-pin 'J1' is a conventional floppy pinout (no power on the connection)   that gives you a standard 34-pin (read: clone) floppy data connection on the board. This is for the PS/2s that have a 5-1/4" bay & the separate drive power plugs.

   The driver only recognizes the 5-1/4" drive types (360Kb or 1.2Mb), but will read a conventional 1.44Mb drive fine (Identified as 1.2Mb. You can also DRIVPARM it to make it appear like it should.). Can't supplant the regular floppy drives this way though: The attached drive is set up as the next available drive letter. If you have a compressed drive that the host partition is "H:" the attached floppy will be "I:". With both an internal & external drive attached to this board the internal drive is configured first. Only one drive can be on each of the connections. The internal ribbon cable should have no twists.

Tim Clark boasts:
   Anyway, the point of all this is that I found that the 1.2MB could be configured as "Drive B:" by editing the system ADF to add the 5.25" drive codes, provided that the later version of SC.EXE (V2.20?) was being used.

>[The Drive Connector Assembly] 72X6755 is a card fitted to a plastic bracket making it fit into the second floppy bay of the 8570 (Ed. works with 50/60/70/80 card edge floppy) I got it from.  It had a connector on the side (34 pin header), which was connected by ribbon cable to the MCA card using a 34 pin edgecard socket (3M 5934).

David Beem again lays it out by saying:
   Nothing more than a pass-through MCA riser. You have to put in a bay adapter & 34-pin connecting cable too.

FixedResources
         io 0280h - 0287h
         int 6

DMA Arbitration Levels
   DMA channel used during data transfer.  Ordinarily, <Level 3> is always selected.
      <"Level 3">,  1, 5, 7

Drive Connector Assembly 72X6755
   Used on 8550, 8560, 8570, and 8580 models with card edge floppy sockets. Not for use with 8565 and 8580 A21 / A31.

34 position card edge slips into floppy socket and assembly clicks into place like a normal floppy.


Note the 34 pin header on underside of Assembly. The 34 conductor ribbon cable then goes over to the 5.25" 360KB External Diskette Adapter FRU 72X6758, where the card edge socket connector fits onto P2.

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