@DDFF.ADF - IBM ESDI Fixed Disk Controller 
     (ADP CDDFF.ADF not required / rename to @DDFF.ADF) 
@DDFF.ADF - IBM ESDI Fixed Disk Controller 
CDDFF.ADF - Init file for _DDFF.ADF 
@8EFF.ADF - IBM PS/2 SCSI Adapter w/Cache 
                 (modified, needs no ADP, ROM selectable / German comments) Use this for IBM ESDI and SCSI Controllers in the same system. 
Early MFM Adapter 72X8540
Later MFM Adapter 90X8643 

ESDI Hard Disk Attatchment
   ESDI EPROM  
   Install Second ESDI Drive  
   Using Non-IBM ESDI Drives   
   8560/8580 HD Cabling Schematic (Signal and Data)
   MFM/RLL Cable Source  
Is the IBM Integrated HD Adapter ESDI?

U30 is covered with a grey-black resiliant compound that has a heatsink? pushed into it?? The edgecards at the top are not labelled. U4 and U7 have the metal can/ceramic construction you love so much. 

Card Identity
From Peter 
   This "Mystery Card" is also a MFM controller, IBM P/N 72X8540. It is a early downlevel card, which has been withdrawn with ECA 002, service  code 33 available from 87-06-17 / IBM Boca Raton. This adapter has been used in early PS/2 Mod. 8560-041 with serial No. range  from 8001342 - 8009651 (US production only). 
   The ceramic shield has been obsolete on the new redesigned MFM adapter for Mod. 60 & 80. These adapters were already a "factory reworked" card - first  series cards had the U30 module without the shield and experienced "sudden death" due to some sensibility against electrostatic discharge. Therefore the shield. The P/N for the various cards stayed (untypically) unchanged. 
   [Source: IBM Engineering Changes Group 819 - PC-Family / PS2 Family Service Information Manual, IBM Doc.No. SR28-0280-2 / 3rd Edition Nov. 1987] 

MFM Controller 90X8643 

From Anarcho-Hacker Peter
   From the principle the stuff IBM used there is the usual Western Digital stuff ... with the major difference of a "BIOS type look-ahead" table with fixed values and no "User Type". Back in the glorious old days we used to solve this problem with a software called "SpeedStore". You enter the BIOS type of a drive which comes closest to the one you want to install and then override the CMOS settings with the software and a boot-sector resident driver. 
   Another significant difference: IBM has castrated the 4-device ST-506 interface down to 2 devices with altering the device adressing a bit. All drives have to be set to "second drive" (DS1 when counting "0"-based from DS0 to DS3). The two possible drives are adressed with the motor-on and drive select lines - and a twisted cable for the first drive, which "corrects" the false adressing logic. The IBM PS/2 BIOS also and consequently supports only two MFM drives (and two ESDI as well ... they repeated the mistake there again). 
   This part is still missing in the PS/2 Reference PDF section. I *think* I have the MFM controller HITRM or TRM anywhere ... but I might be wrong. I PDFed the ESDI and SCSI controllers - which seemed the more important to me. 

U25 appears to be the Even BIOS, U13 the Odd BIOS
Y1 is a unique flat, square clear plastic cased crystal. 

How Many Drives are Supported?
   Two are supported. ESDI natively supported 7 to 8 drives - but IBM (and others) cut that down to 2 or 4 ... the original IBM / WD controller has two ports for drives.

DOWN - level U16
   P/N 90X7399, P/N 90X8635, P/N 15F6587, P/N 15F6807 and P/N 91F7430. 

15F6587 :caused a diagnostic formatting problem and an intermittent hardfile delay during system operation (the hardfile light would remains "on" for approx. 13 seconds). also, in rare instances, a write fault could result in a data shift problem during error recovery, which would be detected during read operations and during diagnostics as a "10473" error (ECC error; read error). 

15F6807 : caused a highly intermittent problem of undetected write faults on the last 1/3 of the last sector written (detected during system read operations and by diagnostics as error code 10473, ECC read errors). 

91F7430 : experienced a highly intermittent system "HANG" only on 115MB ESDI fixed disks. 

NOTE
   Some older versions of direct driver software, which bypass BIOS (basic input/output system) may experience failures accessing the Fixed Disk after the installation of this ECA. This may occur because changing this module may alter how the Fixed Disk subsystem "appears" to the software. Software which uses BIOS is not affected and will function normally. DOS and OS/2 use BIOS. 
If the user software fails after this module is changed, the original module should be re - installed, and the appropriate software support function should be contacted for any possible software patches or updates. 

After Replacement
   After replacement of the module, FRU P/N 92F0062 (P/N 04G3759) advanced diagnostics ESDI fixed disk(s) routine should be run to insure proper hardfile operation. 

Using Non-IBM PS/2 ESDI Drives
>- Will the HD run in my 8580 even if it is nothe original IBM-HD ? 
   As I understand it, the ESDI drives for the 80-class machines had identity data stored on the drive itself. If it's not an original equipment  ESDI drive, or if it *IS* an IBM drive but has since been low-levelled in another (non-IBM) machine, it can't be put back in an 80 unless the Reference Diskette is "cooked". For Peter Wendt's recipie, look HERE

8560/8580 Harddisk Wiring Schematic 
Thanks, Peter!
                    to Power Supply
                      |        |
  +----------------+  |        |    +----------------+ 
  |                |H-+        |   H|                |
  |                |        +------H|                |
  |                |H       |  |    |                |
  |     HD #1      |H-------------\H|      HD #2     |
  |    (Rear)      |H       |  |  /H|     (Front)    |
  |                |      +------/ H|                |
  |                |H     | |  |    |                |
  |                |H---+ | |  +---H|                |
  +----------------+    | | |       +----------------+
                        | | |
                        | | |
                        | | +---------+
                        +-|------+    |
                          |      |    |
         Rear             |      |    |        Front
         L_U-----------HHHHHHH--HHH--HHH-------+---+
          |            J1       J2   J3        |   |
          |                                    |   |
          |                                    |   |
          |    IBM HD-Adapter (MFM or ESDI)    |   |
          |                                    |   |
          +-+HHHHHHHHHHHHHHH+------------------+---+
            +HHHHHHHHHHHHHHH+
 

Cable from J1 to HDs #2 and #1 is  twisted for 5 lines 6 to 10 between HD#2 and #1
The segment between J1 and HD#2 is wired 1:1
Cables from J2 to HD#1 and J3 to HD#2  are both wired 1:1 with no twists

MFM/RLL Cables from RadioSchlock
Dual MFM/RLL Drive Kit   950-0325
28" dual data cable and a 28" dual control cable (?)
MFM/RLL Replacement Cable   950-0326
18" 20-pin IDC to edgecard socket
MFM/RLL Replacement Cable   950-0327
28" 34-pin IDC to edgecard socket

From Peter
The IBM ESDI controller is a 10MHz controller that has a limit on the speed (10Mb/s disk-to-interface) and the sectors (36). So most likely the XT-8760E will not work with that controller. It is a 52-sectors drive and seems to be an ESDI 15Mhz device as well. 

Peter 
   1. The ESDI controller has *not* been announced for use in the later  models after Mod. 80 - so it is no good idea to use it in a 77 of any  flavour. 
   2. If any ESDI drive is recognized during setup the machine BIOS handles it directly on the BIOS-Int Level as system hardware extension (INT 80h device) just like an MFM-drive. The SCSI-Bios is in this case "one step behind" and the MFM (if any), IDE (on "Lacunas") and ESDI-drives like in your case will called first and attached to the Int80h device-call. 
   3. It *might* be possible to use the "Selectable Startup Sequence" in the machine setup ("Features" in the main menu) - but I truely doubt that the startup will "know" the ESDI-drive *because* the adapter is notsupported in that machine. However worth trying and looking atanyway. 
   4. The 16-bit MCA Stage 1 ESDI-Adapter will most likely have some influence on the systems performance. I would recommend to remove it - in case you really plan to do something with the machine and not only do that for curiosity only. The investment in a new faster and larger SCSI hardisk (like the IBM DCAS-32160, 2.16GB Ultra-SCSI) is not wasted money. The system acts a lot more lifely with that. 

>Thank you anyway for your helpful information. 
   Nothing to thank for. I even forgot to mention another nasty effect of this combination: you cannot run Win95 or WinNT with it. Both adapters, the IBM SCSI and the IBM ESDI are hardwired to use IRQ 0Eh (14) and are tied up at the same time. This interrupt-sharing is a technical feature of the MCA - and causes no problem under DOS / Win 3.x or OS/2 ... but Win95 / 98 or NT cannot handle that, because it runs against their "one device / one ressource" strategy. So much for the "guys in Redmont" and their understanding of modern technologies. 
    So if you just tried it for curiosity - you better leave it. I tried something similar back in 1989 with the Mod. 80-311 to add an SCSI adapter for larger drives and wanted to boot from the SCSI ... did not work. The ESDI always started first. This misbehaviour is (as far as I know) buried in the different handling of ESDI and SCSI from the BIOS. 
   If anyone else finds a way - okay - I am interested. But as far as I know - and from my own experimenting - it does not work. (Also: Mod. 70 with IBM SCSI and SCSI-HD: also starts from the DBA-2 ESDI drive first) 

(Ed. Peter points out the 16 bit compatability mode the SCSI and ESDI controllers create. So you can run W95 with this setup, but...) 

>You are right it will be much better to invest some money for a new SCSI drive. 

  Please keep in mind that the 9577 with the onboard-SCSI is limited to a drive size of 3.94 GB (corresponding to IBM) for the "first drive to boot from and which holds the system partition". This point was topic on an older (or: several older) threads in this group. Therefore I recommended the 2.16GB IBM and not the 4.2GB ... ! But any modern 2GB - 3.5GB drive will do fine. Quantum makes (made ?) a Fireball with 3.5GB capacity. This would mark the maximum installable in the Mod. 77. The "over 4GB" appear to be installable, are even recognized with the exact capacity - but the IML-partition will not be installable. Now: will install - but will not work. And then you ran in a nasty IML-error of the I999 00nn category. 
     That for completeness. 

Secondly the DF9F HD / controller combo was primarily designed as "single device". The later @DF9F.ADF allowed to set one as "primary" and one as "secondary". But as far as I know this has been included to match an early draft of the PS/2 Mod. 90 hardware .... which *had* two integrated harddisk controller ports at the front end of the sysboard. These however had been made non-functional in the later platform BIOSes and don't work. I have played around with them in the early 90s but found no clue to get them working with any Type 1 - 3 platform. As well as Alfred Arnold tried recently - don't know if he gave up yet.

I hadn't been that desperate to try installing the 386DX-20 (Type-0)
platform in my 8590 and see if I get the front drivebays going with that.

Due to the lack of appropriate connectors none of the PS/2 machines support two integrated harddisk adapters. These *are* MCA connectors. The 72-pin layout of these drives is basically a slightly stripped-down 16-bit MCA connector. And the planar ADF for e.g. a Mod. 55SX says "4 slots" where the Slots 1 - 3 are for expansion cards and Slot 4 is at the end of the riser card - extended with a flat-ribbon cable over and down to the harddisk. 

And - No - you cannot just crimp another 72-pin connector in that cable.
There are signals that select the slot number - and that for this "cable port" is fixed set to Slot 4 ... so any other connector on that cable would signal
"Slot 4" to the sysboard.  It is -as said- "stripped down" ... means: apart from some DC- and GND-wires also "other unimportant signals" are not passed over to the HD-connector.