991209    6886  ( PC750 MCA ) 

      Got a 6886-45H .  It was treated as " used computer" but seemed to be new .
 

 Specifications
  CPU         ;  P-90MHz
  SIMM        ;  16MB ( 8MB x2 )
  HDD         ;  720 MB ( DSSA 3720 )
  CD ROM  ;  ATAPI  2x speed

Got a latest BIOS flash program and reference/diags from IBM FTP site.  Flashed up to N2JT50A ( now updated to N2JT52A .  50A is only available at IBM FTP site. see below   ) and put a K6-II/300 using  PowerLeap interposer PL-Pro/MMX-Plus.  Installed Win95B.  Worked fine. 
Later on I added Madge Smart 16/4 and S3 Virge DX ( now the video has been changed to Matrox Millennium-II 8MB ) ,  6GB Seagate hard drive then  I  hooked an external 36.6K  modem.  Thus 6886 became a internet service machine in my room. 

Related files
  Product Index
  Software and Device Drivers
  N2MT28A.EXE   Refference Disk for PCI/MCA models
  n2jt50a.exe        Flash Update utility
  n2jt50a.txt          readme txt for above utility 

PC 730/750 Series (Type 6875, 6876, 6885, 6886) - Pentium 75/90/100/120/133 MHz System Board: 

Outline was stolen from IBM manual       Bus/CPU Speed MHz Setting:  Jumper  50/75  60/90  60/120  66/100  66/133  J26  2-3  2-3  1-2  J27  2-3  1-2  1-2 Cache Jumper Settings:.   Cache  J21  J22  J23  J24  256 KB  1-2  1-2  1-2  1-2  512 KB *1  1-2  1-2  2-3  2-3  1 MB    *2  2-3  2-3  2-3  2-3   Never seen a Cache RAM for 512KB nor 1MB.

1    Riser connector 2    Modem Ring Detect connector ( J15 ) 3    Diskette drive write protect jumper ( J29/ WP ) 4    Diskette drive connector 5    Hard disk drive connectors        0=Primary, 1= Secondary 6    On/Off Switch power supply connector  (J38 ) 7    On/Off Switch connector  ( J37 ) 8    Power supply connectors 9    L2 Cache size jumpers 10  Processor connector 11  Bus/Core Ratio  ( J19 ) 12  Cache connectors 13  Memory connectors (Bank 2) 14  Memory connectors (Bank 1) 15  Memory connectors (Bank 3) 16  Video memory connectors 17  Power-on password jumper ( J40/PWD ) 18  Battery 19  Display connector 20  Parallel connector 21  Serial connector 22  Serial connector 23  Mouse connector 24  Keyboard connector 25  Audio jack ( Input jack ) 26  Audio jack ( Output jack ) 27  IDE CD-ROM audio connector 28  Mouse jumper ( J28 ) 29  Bus/CPU - Speed select jumper (J26/J27)  30  Hard Disk (1-2) / Power LED (3-4)  31  Fan 32  Front-Panel (Audio)  33  Speaker (3-4)  34  Power Connector 35  Mute (Audio)  36  Mute (Audio)  37  AUX1 (CD-ROM)   The jumper setting information.   Upper RED is default.  Jumper  Setting  Description  J19  Open  Short  2/3 Bus/Core Ratio  1/2 Bus/Core Ratio  J28  1-2   2-3  Mouse enabled   Mouse disabled  J29   (WP)  2-3  1-2  Enable writing to a diskette  Disable writing to a diskette.  J40  (PWD)  1-2  2-3  Password enabled.  Password reset.

*1  Option Guide doesn't mention about 512KB  setting.       It's written in  Product Index stored in IBM WEB Site. *2  TAG RAM:  Socket  #10 is vacant for stock 256KB        configuration.       According to Manual, One more "TAG RAM" should be      installed in socket #10 for 1MB cache configuration. Originally 8x cache chips are installed in socket 2 to 9.  Each cache chips should be installed like illustlated right.

 

Tips 
OPTI- DUAL PCI IDE Controller can not be properly recognized under Win95.
This symptom observed on some 6885 and 6886 ( not on every machines ). To solve this problem you need to rewrite Win95 system registry by  following steps. This instruction was once available in OPTI's web site. 

   1.  From Windows 95 click Start
   2.  Click Run
   3.  Type in "regedit"
   4.  Click OK
   5.  Double Click HKEY_LOCAL_MACHINE
   6.  Double Click System
   7.  Double Click CurrentControlSet
   8.  Double Click Services
   9.  Double Click VxD
 10.  Double Click IOS
 11.  Double Click NoIDE 01
 12.  Change the value to 00
 13.  Close regedit
 14.  Restart the system 1)  From Start > Run execute with file name

If you get into the trouble at the final stage of  installation and Win95 breaks into  blue screen and the system can not go further to complete installation. then choose safe mode operation to do above modification.   Hit F8 key to get  boot menu so that you can select  Safe Mode operation . Once the system get booted in safe mode,  you can apply above mentioned steps.  In some case Win95 may be installed properly  without above error. Don't know why. 

HD limitation
BIOS may not recognize HD > 4.2GB 
If the drive is larger than 4.2GB and it's a 16 Heads logical drive,  BIOS can't recognize it properly. EZDRIVE may help you..

If  the drive is a 15 Heads logical drive, then  you can use 6GB drive ( I suppose  8 .4G is it's limit but  these days there are no such 8G drives with 15 heads  ).   I've used a seagate 6.4G drive without Seagate Disk Wizard utility.

SIMMs
You can use 32MB 60ns/70ns Parity SIMMS.
6885 ( PCI/ISA version ) can take EDO SIMMs but I have not tested EDO on mine.
Sander Fransen wrote in his page that 6863 could  take EDO SIMMs. 6886 could do that too.
Watch SIMM socket layout. BANK 1 sockets are the two in the middle ( # 14 in above layout ).

Video
Onboard video chip is S3 Vision 868.  Video Disable jumper is not ready on the planar. 
If you want to use a PCI video card under Windows 95, disable S3 video under device manager section in the Control Panel.

PCI Video card known to be usable on this machine
     S3 Virge DX4 based card
     Matrox Mystique
     Matrox Millenium
     Matrox Millenium II

CPU upgrade
The Planar itself supports Classic-Pentiums rated upto 133MHz. VRM socket is not ready on the Planar. 
In order to use CPU rated higher than 133MHz,  you need an interposer. Fo MMX CPU, you need a voltage interpser.
   K6-II/III-400 can be used with an appropriate interposer. PowerLeap interposer is my favorite one.
   Connect the power connectors FIRMLY or your interposer ( and your K6 CPU ) will get toasted.

I've tested following CPUs and all of them worked nicely on an PowerLeap Interposer ( PL-ProMMX Plus) 
    MMX166 and 233
    K6-300
    K6-II/400
    K6-III/366 and 400.   K6-III series require PL K6-III.  PL-ProMMX Plus doesn't work ( for me ). 

   AMDK6UPD.EXE  is required to use K6-2/350 or faster on Windows 95B/95C reffered 
   as OSR2/2.1/2.5.
   Japanese explanation is HERE. 
   Also refer Knowledge Base Q-235249 if you use M$ Backup. 

   For Japanese reader
    PKK6.ZIP      IO DATA PK-K6H series support software Ver. 1.02
    HK6_2.EXE   BUFFALO ( known as Melco ) HK6 series cache utility disskette ( requires 
                          1.44MB floppy )

HDD carrier 
When you disassemble the HD structure from the box, UNPLUG  the AC power cable from AC inlet    connector .
System board and the Riser card are "alive" even if the main power is "OFF" and the AC power plug  is connected to the wall outlet ( I mean DC current is supplied always even though the main power   SW pushed off ) .   If the metal structure touches the solder side of the riser card,  the riser will get damaged very  easily. 
So again,  Please Take my Advice.   I fried riser cards in my 6885 ( PCI/ISA ) twice. 
After that  I affixed a sheet of vinyl onto side wall of  HD structure facing to the solder side of the riser. 

What to do if wrong BIOS Flash applied 
I myself have not examined but it was reported to the news group 2 or 3 years ago. 

If you applied  wrong BIOS version for 6885 PCI/ISA system on your 6886/6876,  you need a BUS Riser card  for 6885.
Install PCI/ISA BUS Riser on your 6886 and once configure it as a PCI/ISA system.
Then apply CORRECT BIOS FLASH program ( N2JT50A ).  Pull off the PCI/ISA Riser and change it to original  PCI/MCA  riser card.