Reference disk for PS/2 P75 486 luggable
System P75 (8573) IBM Parts ($$$!!!!)
P75 System Board
Indicator Port Pinout (J17)
Storage Device Cable Source
Remove Floppy Drive (H1 Model)
Hard Drive Removal
System Unit Fan (Remove/Install)
Power Supply Unit Checkout
Remove Power On Password
Built-in Features ADF
|15F OKI 15F7917
4464 Hitatchi 4464S-08LL
82077 82077AA Floppy Controller
8032 80C32-1 CPU
Even, Odd SCSI BIOS 79F3214 E,
F1-3 Fuses in power traces
F4 Fuse for floppy?
I7 Hitatchi 4464S-08LL
IC5F DMA Controller 90X8134ESD
J4 RS232C DB25
J5 External Floppy
J7 Bus riser
|J9-12 72 pin SIMMs
J13 SCSI internal
J14 External SCSI C60
J21 HDD Power
JP1 Power On Password
SCSI3 OKI 33F6910
SI outline for 5 pin header, "SCSI
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
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.
1-2 Power LED
3-4 HD LED
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 2 (Long)
32-bit AVE 32-bit
Slot 5 (Short)
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
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.
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
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
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.
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)
Storage Device Connector
Shared with the P70, look HERE
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.
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.
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.
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.
PN 64F8775 FRU 64F8789
OSC1 66.6666 MHz
ROM PN 64F9924
Upgrade (Dr. Jim Shorney's site)
PN 78F9895 FRU 78F9897
|44256 Hitachi 44256S-10LL
CN1 Plasma panel
CN2 External video
J1 Not a clue
J2 Not a clue
|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
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!
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
To have standard text brighter than emphasized text, type "BRT /H"
and press Enter.
P75 System ADF
0E0FFh AdapterName "Built In Features"
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
The built-in parallel port connector
can be assigned as Parallel 1 through Parallel 4 or disabled.
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
Allows the system board processor to preempt continuous
data transfers by other devices for its use of the Micro Channel.
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.
2160h - 216Fh>, Instance 1: 2110h - 211Fh, Instance 2: 2120h - 212Fh,
Instance 3: 2130h - 213Fh, Instance 4: 2140h - 214Fh, Instance 5: 2150h
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.
13>, 12, 11, 10, 9, 8, 14
Video Fairness indicates
whether or not the video sub-system coprocessor will follow the fairness
algorithm for bus usage.
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.
20 Minutes, 30 Minutes, 60 Minutes, 120 Minutes, 1 Minute,5 Minutes
There are two ways to turn on the display again:
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>.
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
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.
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