8573 P75
rfp75a.exe Reference disk for PS/2 P75 486 luggable
Mobile System P75 (8573) IBM Parts ($$$!!!!)
P75 System Board
   Indicator Port Pinout (J17)

Floppy Drive
   Floppy Controller
   2.88MB Capable?
   External Storage Device Connector
      External Storage Device Cable Source
   Remove Floppy Drive (H1 Model)
Battery Pack
Processor Card
Video Card
Brightness Program
Hard Drive Removal
System Unit Fan (Remove/Install)
Power Supply Unit Checkout
Remove Power On Password
Built-in Features ADF

P75 Planar  78F9896

15F OKI 15F7917
4464 Hitatchi 4464S-08LL
82077 82077AA Floppy Controller
8032 80C32-1 CPU
Even, Odd SCSI BIOS 79F3214 E, 3213 O
F1-3 Fuses in power traces
F4 Fuse for floppy?
GA2 64F8781
GA3 79F3196
GA4 79F3242
GA5 79F3202
I7 Hitatchi 4464S-08LL
I56 79F3200
IC5F DMA Controller 90X8134ESD
J1 Keyboard
J2 Mouse
J3 Printer
J4 RS232C DB25
J5 External Floppy 
J6 Display
J7 Bus riser
J9-12 72 pin SIMMs
J13 SCSI internal
J14 External SCSI C60
J15 Speaker
J16 Floppy
J17 Indicator
J19 Processor
J20 MC-2
J21 HDD Power
JP1 Power On Password 
MC146818 MC146818AF
SCSI3 OKI 33F6910
SCSI7 33F6715
SI outline for 5 pin header, "SCSI ID"
TP 8 pin Term Packs IR6-8
uCode PN 79F3212
X1 20.0000 MHz osc
X2 32.768k? xtal
X3 14.31 MHz osc
X4 24.0000 MHz osc
X5 20000 xtal KHz?
X6 12500 xtal KHz?

J8 Wire Colors
Pin1 on left, pin 10 on right (silkscreened on board)
Blue (9), Orange (10), Red (11), R (12), R (5), Black (8), Bk (1), Bk (2), Bk (3), White (4)
Numbers in parentheses are the corresponding power supply connector

Indicator Port (J17) Pinout
   This is the Indicator port- three LEDs are driven off this header, Power, HD, and Floppy. Note that the header on the system board and the display card (PN 65X1569) are keyed, so the pins match from 1 to 1, 2 to 2, and so forth.

Pin   LED
1-2   Power LED
3-4   HD LED
5-6   FDD

Slot Numbers and Widths
   The two upper slots are 32 bit. The slot next to the rear cover has the AVE (dow! case is shut!) connector. The bottom two slots are 16 bit, and they are short. FWIW, Slot 1 is the internal SCSI controller.
Slot 4      Slot 2 (Long)
32-bit AVE  32-bit
Slot 3      Slot 5 (Short)
16-bit      16-bit

This is a mix of the Adaptec AIC-6250EL, the OKI 15F7917, 33F6715 , 33F6910  and the N80C32-1 cpu. To me, it resembles the short SCSI /A.

SCSI BIOS PN 79F3214 (even) / PN 79F3213 (odd). SCSI microcode PN 79F3212
It uses three 8 pin SIPP term packs.

Up to six SCSI devices can be attched to the SCSI controller.

DMA Controller
  90X8134ESD, just like on the K and 0 complexes and the 50Z planar.
J17 six pin header for floppy drive, power, and hard drive LEDs
J20 MC-2 14 pin header that connects to riser card.

   2MB, and 4MB 70nS parity SIMMs are supported, maximum 16MB on the planar.

Load SIMM sockets from top to bottom, largest SIMMs (memory size) first, smaller simms last. The notch in the SIMM goes to the left (towards the outside of the case)

NOTE: If (4) 4MB SIMMs have been installed, it may take up to 10 minutes for the IBM screen to come up when reconfiguring with system programs. Or just using the system. Damn, it counts slow...

Floppy Drive
   The floppy can be used in the open or closed position. It is recommended that it is operated in the closed position so the chance of  foreign material dropping in the drive is greatly reduced.

The floppy in my P75 is a ALPS DFP723D15C, 12v .47A, 5v .16A

Floppy Controller
  It's a 82077AA. Probably supports 2.88MB floppy drives (yea! got to love the dust shutter), but NOT the " * " marked 2.88MB floppy drives.

2.88MB Capable BIOS?
This is from the HMM- note the reference to a "4MB Media Sensor"....
3.5-Inch Diskette Drive  38F5936
3.5-Inch Diskette Drive  38F5936 (with 4MB Sensor)

External Storage Device Connector
  Shared with the P70, look HERE

Floppy Drive Removal
  I finally got Dr. Jim to speak in a way you can all understand (Cult of Personality).

From Dr. Jim (I'm an engineer, not a doctor)
   OK, this is not rocket science, especially if you have an H1 floppy. 

Reach in behind the display panel with your left hand. Slide your index finger in behind the floppy housing on the left side  about 3/4 of the way up.  Then slide your finger downward along the edge of the housing until it stops on the catch.  At this point, hook your finger behind the left side of the housing and pull the side of the housing to the left, maybe 1/4" or so.  Once the little post on the floppy cover clears the catch, the floppy will flop forward. 

Continue to rotate it until it is level, then pull it straight out.

Removing Floppy from Drive Carrier, H1 Model
   Warning! There is a aluminum ground shield across the bottom of the floppy drive. It is attached with four screws through the bottom mounting holes (which are not used by the plastic "rails"). It is coated on one side with a plastic non-conductive coating. To properly attatch this shield, the grounding strap "tab" MUST be on the same side as the motor! A simple test- use an ohmeter on the shield, one side conducts, the other, not.

Battery Pack PN 79F3198 (Entire assembly)  Battery Card, PN 64F8794
  The P75 uses a 6V battery pack, with two Panasonic CR2477 3v cells soldered to a circuitboard.
The battery header (J18) is a four pin header with one pin missing. The plug on the end of the battery card cable has one position plugged. 
 -  |    +
 O  O  X  O
Battery Card plug  "X" is plugged. "|" is open.

Processor Card PN 64F8775 FRU 64F8789

IC5 486DX-33
OSC1 66.6666 MHz
ROM PN 64F9924
P75 CPU Upgrade  (Dr. Jim Shorney's site)

Video Card PN 78F9895 FRU 78F9897

44256 Hitachi 44256S-10LL
CN1 Plasma panel
CN2  External video
DAC32 37F0842
J1 Not a clue
J2 Not a clue
PDPC 53F8674
TC524256 Toshiba TC524256J-10
VRAM Toshiba TC524256AZ-10
Y1 25.175 MHz PC 640x480/ 400 modes 
Y2 41.539 MHz PC 132-columns mode 
Y3 28.322 MHz VGA / Text mode
Y4 44.900 MHz PC 1024x768 43.5Hz (I) mode 
Y5 40.000 MHz DMA Clock / 2 
   PC = Pixelclock

A lot of these are used on the XGA adapter.

Any further info on the jumpers or chips? Tell ME!

Brightness Program 
 To install Brightness program, run Brtinst.com from the refdisk. This installs brt.com.

To have emphasized text brighter than standard text, type "BRT" and press Enter. 
To have standard text brighter than emphasized text, type "BRT /H" and press Enter. 

P75 System ADF 0E0FFh AdapterName "Built In Features"

Serial Port
   The built-in serial port connector can be assigned as Serial 1 through Serial 8, or disabled.

   <SERIAL_1  03f8-03ff int 4>, SERIAL_2 02f8-02ff int 3, SERIAL_3 3220-3227 int 3, SERIAL_4 3228-322f int 3, SERIAL_5 4220-4227 int 3, SERIAL_6 4228-422f int 3, SERIAL_7 5220-5227 int 3, SERIAL_85228 -522f  int 3, Disabled

Parallel Port
      The built-in parallel port connector can be assigned as Parallel 1 through Parallel 4 or disabled.
     <PARALLEL_1 03bc-03bf 1278-127f int 7>, PARALLEL_2 0378-037f int 7, PARALLEL_3 0278-027f int 7, PARALLEL_4 1378-137f int 7, Disabled

Parallel Port Arbitration Level
   The built-in parallel port connector can be assigned any one of the available arbitration levels 0 through 7. Select <Disabled> to use the parallel port in compatibility mode. 
   <Level 6>, 5, 4, 3, 1, 0, Disabled, Level 7

Preempt Enable/Disable
   Allows the system board processor to preempt continuous data transfers by other devices for its use of the Micro Channel.
     <Enable>, Disable

Video I/O Address
   This selects a particular I/O address range for the Display Controller Registers. This field also affects the exact location of the video coprocessor registers.
      <Instance 6: 2160h - 216Fh>, Instance 1: 2110h - 211Fh, Instance 2: 2120h - 212Fh, Instance 3: 2130h - 213Fh, Instance 4: 2140h - 214Fh, Instance 5: 2150h - 215Fh

Video ROM Address Space
    This defines the memory address range used for the system video ROM.
      <C0000 - C1FFF>, C2000 - C3FFF, C4000 - C5FFF, C6000 - C7FFF, C8000 - C9FFF, CA000 - CBFFF, CC000 - CDFFF, CE000 - CFFFF, D0000 - D1FFF, D2000 - D3FFF, D4000 - D5FFF, D6000 - D7FFF, D8000 - D9FFF, DA000 - DBFFF, DC000 - DDFFF, DE000 - DFFFF

Video Arbitration Level
       The video sub-system can be assigned any one of the available arbitration levels 8 through 14.
     <Arbitration level 13>, 12, 11, 10, 9, 8, 14

Video Fairness
        Video Fairness indicates whether or not the video sub-system coprocessor will follow the fairness algorithm for bus usage.
     <Fairness On>, Fairness Off

Auto-Dim Time
        Auto-Dim function automatically turns the plasma display off after a specified period if no input from the keyboard or auxiliary device is received. Auto-Dim Time can be assigned from 1 to 120 minutes.
     <10 Minutes>, 20 Minutes, 30 Minutes, 60 Minutes, 120 Minutes, 1 Minute,5 Minutes 

Auto-Dim Reset
   There are two ways to turn on the display again:
           1. Pressing SHIFT
           2. Clicking the mouse.
        If the mouse picks up vibration on a desk which turns on the display again, change Auto-Dim Reset from <Keyboard and Aux. Device> to <Keyboard Only>. 
        <Keyboard and Aux. Device>,Keyboard Only

Color to Gray Mapping
     There are some applications that are developed for color displays but can be used on monochrome displays. When using such applications, reset Color-to-Gray Mapping to <Green Signal Only>. Setting <RGB Mixed Signals> may result in an unpredictable display image.
  <RGB Mixed Signals>, Green Signal Only

Turned-on Display
      Primary turns on only one display that is considered by the   system to be the primary display.  When no external PS/2 display is connected to the system unit, the plasma display is considered as the primary display. Only VGA mode is supported.  When the external PS/2 display is connected, it is considered as the primary display. VGA or XGA mode is supported for the external PS/2 display.
         Plasma and External turns on both the plasma display and the external PS/2 display. Only VGA mode is supported. 
   <Primary>,  Plasma and External

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