5.25" External, Internal Diskette Drive, and Diskette
189-077 IBM PS/2 5.25-Inch
External Diskette Drive, 5.25-Inch Internal Diskette
Drive, IBM PS/2 5.25-Inch External Diskette Adapter/A
@DFFA.ADF - 5.25" Diskette Drive
Adapter (1.2MB card only!)
4869drve.exe 1.2MB Floppy
Adapter Option disk
4869DRVR files in
IBMDSKT5.EXE Installation Program for the
5.25-inch Diskette Device Driver
$FDD5.SYS DOS Diskette Device Driver
EXT5DD.SYS - OS/2 Diskette Driver
4869 External Diskette Drive
The much beloved "Battle Floppy"
5.25" 1.2MB / 360KB External Diskette Adapter
5.25" 1.2MB /
360KB External Diskette Adapter
8590/95, 486SX-25MHz Diskette Data Loss
External Diskette Adapter Lacks any POS
for 1.2MB Version
Assembly (Plastic "B" Box)
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
||8550 / 8570
||8560 / 8580
1 - > 72X6759 (360KB DRIVE)
4-> 15F7996 (ADAPTER/A CARD)
2 - > 72X6757
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
** 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
- 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
- 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
- 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.
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
5.25" 1.2MB / 360KB External Diskette Adapter
|J1 34 Pin
S1 Unused four
position DIP switch
U1 NEC 72065C
Y1 32.000 MHz
Y2 19.200 MHz
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 &
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
1.2MB / 360KB External Diskette Adapter FRU
U4 15F8072 may be
similar to the Epson SED9420 CMOS Data Separator for FDD
|J1 34 Pin
|U12 NEC D765BC
Y1 19.200 MHz
Y2 32.000 MHz
Allows the 4869-001 or 002 to be attached to the
8550, 8560, 8570, or 8580 system unit or the diskette
drive (6451006) to be attached to the Personal System/2
8560 or 8580 system unit. A device driver is used
with the 4869 or PS/2 Internal Diskette Drive (6451006).
This adapter can accommodate up to two 5.25-inch diskette
drives, one external and/or one internal drive in the
following system configurations:
ONE DISKETTE DRIVE
MODELS 50, MODELS
60, 70, 80 60, 80
4869-001 or 6451006
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
486SX-25MHz Diskette Data Loss
Systems with a 486SX/25MHz [“H”]
complex that use the VERIFY function during
"Diskette-Like Operations" may fail, allowing bad data
to be read from or written to a device without any error
indication or other evidence of system failure.
* "Diskette-Like Operations" are defined as operations on
any device attached to the diskette drive controller and
are "seen" by the system as a diskette drive, such as
some tape backup devices.
Note: Most "H"
complexes have a bad DMA controller [U6 92F1428]. Late
"H" complexes [made early 92 on] can have 10G7808 (known
Good) or 10G4714 (Possibly Good)
H complexes with 48G8042 on sticker below CPU have U23
Complex PCB is 06G6870, BIOS 07G0463, DMA 10G7808
H complexes with 07G3152 on sticker below CPU do NOT have
Complex PCB is 06G4561, BIOS 07G0463, DMA 92F1428
Systems with the 486SX/25MHz [“H”]
processor board and version 1.00 or 1.01 system
partition are subject to this problem. Devices that rely
on BIOS support are [potentially] supported after an
update of the system partition to the latest level.
The 5.25 inch Diskette Adapter/A uses a separate device
driver (not BIOS), and DMA VERIFY. They are exposed to
the problem after updating the system partition.
IBM PS/2 5.25 inch Diskette Adapter/A
IBM PS/2 4869-001 360KB External
IBM PS/2 4869-002 1.2MB External
Note: H complexi
with the good DMA controller, 10G7808, MIGHT not be
This tip replaces expired ECA100
360KB External Diskette Adapter FRU 72X6758
The 360KB adapter has three small ICs to the
left of P3. The rest of the "adapter" is bare. This
adapter is intended *only* for the 360K version of
the IBM 4869-001 external
5.25" drive (embossed "Star" symbol in the faceplate of
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
Sections AdapterID DFFAH
AdapterName "5.25-inch Diskette Drive Adapter"
0280h - 0287h
DMA Arbitration Levels
DMA channel used during data
transfer. Ordinarily, <Level 3> is always
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.