7552 Processor Module
7552 Resource Module
7552 DASD Module
7552 Extended Memory Module  (16MB with 2MB SIMMs))
7552 Memory Expansion (512KB - 3MB with ???)
7552 Power
7552 (maybe 7568) DO BIOS

Early 7552 Keyboard Pinout
Digital Output

This is the little brother to my beloved 7568-D40. It shares the same case and shroud setup.

The 1784-KT2 Communication Interface Module can be inserted into any 8- or 16-bit mca expansion slot. The 1784-KT2 : makes your PS/2 computer an active node on Data Highway Plus provides single cable connection to a PLC-2, - 3, or -5 family programmable controller
operates with 6200 programming software
when combined with Allen-Bradley 6001-F1E2 software, allows you to
create your own custom interface to Data Highway Plus

The 1784-KT2 has been verified for the following computers:
Allen-Bradley 6123, 6124
IBM PS/2 7541, 7561, 8550, 8555, 8560, 8570, 8580

6123/6124 User’s Manual (publication 6123-2.1).

The following sections provide directions for connecting a 1784-KT2 to a
PLC-2, PLC-3, or PLC-5.

Required Cables for Connecting to a Programmable Controller

Use this cable:	When connecting to:
1784-CP2	PLC-2 Family Programmable Controllers
1784-CP3	PLC-3 Family Programmable Controllers
1784-CP	PLC-5 Family Programmable Controllers
1784-CP6	PLC-5/40 and PLC-5/60 Programmable Controllers (pub 1784-2.26)
1784-CP7 Adapter with 1784-CP Cable	PLC-5/40 and PLC-5/60 Programmable Controllers (pub 1784-2.29)

Computer Oddity 2001
David Bowman saved one and his statement to the world-
   I've got it too boot, used a screwdriver to bybass that "locked" keyboard feature.  It runs to a screen telling me to hit F1 to continue (looks like the Setup feature might be bios based?).

Early 7552 Keyboard Pinout 
Pin    Connection
  1     Clock
  2     Ground
  3     Data
  4     +5v Detect
  5     -KB Detect
  6     -RTI
Ring  Shield Gnd
 

   The only problem so far is the lack of a Keyboard, or at least a suitable
one.  Its the size of an AT keyboard, but one of the pins is in the middle of the DIN.  I didn't see a keyboard and not till it was too late to go looking for the original, noticed this particular port.  I hope IBM's done this before and the pinout is known and a standard keyboard CAN be fitted to this one
   Keyboard offers separate typewriter and numeric keypads. Depending on the application program, from 10 to 40 special function keys may be supported.  The keyboard is attached to the 7552 via a 12-foot coiled cable, permitting a variety of workspace configurations.
 (Ed. The late models used a "standard" keyboard, either AT or PS/2)
   When the 7552 is configured without diskette, keyboard, or display, an IBM 5531, 7531 or 7532 Industrial Computer or another 7552 configured with a diskette, keyboard, or display is required as a remote terminal to load programs and to provide an operator interface for the 7552.  A Remote Terminal Interface (#6078) is required in the 5531, 7531, 7532, or other 7552 to provide an interface to the 7552 through its keyboard port.  IBM program product 5601-053 provides program utilities to support the remote terminal interface functions.

   It does have what appears to be a card slotted in with a 9 pin monitor
output and 2 composite outputs (assuming its video)   (Ed. EGA?)

Data Output Point Circuit

   These points are optically isolated. They are active "on" or "closed" opto-coupled outputs. Each point is capable of switching a voltage source of 5 to 30 Vdc at 30mA load. The voltage drop across the DO point depends on the load, but is typically about 0.8v.
   The DO points are driven by a Texas Instruments TIL157A Optocoupler, with an input- diode forward current of 15mA.

Data Output BIOS Function Calls are HERE

IBM PC FEATURE ADAPTER (#6077): One required for each IBM PC feature adapter to be plugged in the 7552. It provides an interposing card and other hardware to mount the IBM PC feature card in the 7552 card shroud. (Ed. Yes, this is the mythical ISA card interposer foretold of by Brother Tony)

Floor standing feature (#6098) or a rack mount feature (#6097) can be purchased. The floor standing feature provides all necessary hardware to mount the 7552 in the floor standing position and provision to bolt the system unit to the floor.  The rack mount feature provides all necessary hardware to mount the keyboard in a standard 19" rack. The rack and/or panel mount hardware for the system unit is a standard component of the 7552 and is shipped with the system.

MEMORY ADAPTER (#6074): Permits the addition of up to 3Mb of memory. The first 512Kb increment of memory is included with this adapter and five 512Kb Memory Expansions (#6075) can be added, for a total of 3Mb of additional memory.
512K MEMORY EXPANSION (#6075): Each #6075 adds 512Kb of memory to the Memory Adapter (#6074).  Maximum: Five.