RS6K SCSI I/O Controller 4-1
8D77  (4-1) SCSI SE High Performance Internal/External I/O Controller FC 2828

WD33C93A  WD33C93A Datasheet (from Romania!)

SCSI I/O Controller 4-1, FRU 31G9729
D1 Diode
DL1,2 PE 23111 Delay Line
F1 1A, 125v Littlefuse (fast blow)
J1 High Availability Jumper
U1,5 Sony CXK58257AM-12L
U2 31G9727 SCSI BIOS?
U3  31G9725 SCSI BIOS?
U11 80C186-16
U13 31G9723 
U17 81F8929ESD
U36 WDC WD33C93A
Y1 31.9500 MHz Osc
Y2 39.95 MHz Osc

Interrupt levels 3, 4, 5, 7, 10, 11, 12, 14

J1 (also called P3) High Availability Jumper
  Must be out of the circuit for high availablity ("Y") configuration. Put the jumpers over one row only so you don't loose them. There are 13 pairs of pins. You will need a 6 and 7 pair berg jumper (ganged jumper) in order to use this for normal SCSI configuration..

  OK, what do we got?
o   Accepts multiple commands per device  SCSI chain
o   SCSI burst 4.0MB per second (synchronous) SCSI-1 transfer
o   SCSI initiator (command issuer)
o   SCSI parity support                  IBM standard
o   One adapter per system               Software issue?
o   Micro Channel Interface
    -   4-byte (32-bit) Bus Master        Look at the MCA connector...
    -   Streaming data support            Good for a SCSI-1 adapter.
    -   Address and data parity support   Fine

Stephan Goll says:
   To make a summary: AIX has a database called ODM. In this database there are the definitions and suggestions for configuring all the cards not configured before IPL. Cards where AIX can boot from, well, shold be configured somehow, I believe by the ROS (or BIOS). Makes sense, because only the ROS knows from where the box can IPL. And remember, AIX uses a two stage boot process, first it boots in minimal mode, configures the cards using the ODM, and then it boots again with the system fully configured (so it is written in my AIX survivel guide).

Overload Protection and Terminator Power (Term Power)
   The SCSI controller provides term power for the SCSI bus; connect devices to the bus so they do not provide term power. The controller uses a fuse that must be replaced after failure.
   Do not connect or disconnect any SCSI device while power is on. Such “hot plugging” is forbidden because this practice may blow the controller fuse, corrupt data or permanently damage SCSI controller chips in controllers or devices.
  The fuse on an SCSI controller protects the external and internal SCSI bus. The fuse may be blown by a defective cable, terminator, or device attached to the controller, but not by a defective controller.

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