Interposer , "Geta", For Processor Upgrade

For 486/5x86 CPU 
 General  Information 
PGA DX4/2      4x,  JC World  ? 
EverGreen586   4x, 
EverGreen        4x,   AMD/QFP
PL586              4x,   PGA Type 
PL586              4x,   AMD/QFP 
JC World          4x,   AMD/QFP 
HAS-33T         3x,   Melco 
ACE486DX       3x,   Taiwan Made 
            Pin Assignment

         For Pentium class CPU 
          386 Processor Upgrade


Interposer,  geta,  for 486 class CPU 

General Infomation
486 CPUs  in  SX/DX/DX2 line made by intel work in 5V I/O voltage.  Intel DX4 and other High Power CPUs sold by Cyrix and AMD work in 3.3V to 3.45V  I/O voltage. 
In order to use such CPUs on PS/2 or PS/55, you need to use an interposer  which switches down planar 5V to required voltage for those CPUs.
If you put a plain DX4-100 in your Bermuda or K/H complexes,  your CPU will get toasted in someday  ( not  immediately but slowly. I myself didn't imagine that DX4-100 would  work with 5V supplied but it could work actually.  Not tested with Cyrix or AMD though ). 

These interposers usually have jumper blocks for  
   1)   Multiplier selection, 
   2)   WT/WB selection, 
   3)   I/O voltage selection,
   4)   socket type selection
   5)   Intel/AMD selection. 

Appropriate setting of an interposer for each CPU is needed to get full potentiality of these high  powered  CPUs. 


But so far, your CPUs will not get toasted with *wrong* jumper setting unless you put your
CPU onto the interposer with wrong orientation of pin #1 ( as far as I know,  486/586 CPU will not  get toasted with it. 386 and pentium will immediately go to heaven ) or you erroneously set CPU off on "one-row" beside  correct position ( this will also send your CPU to heaven at once ) .    Of course I'd like to advice you DO not test such stupid trial, OK ?

According to old PC magazines sold in 486DX100 era, there were compatibility issue for interposers and DX4 and /or AMD/Cyrix.  An interposer worked OK with DX4-100 on a system A  but not good on system B. The other was OK on B but not on A.  
One of PC upgrade shops sold various versions of  AMD upgrade interposers  which were arranged to work with specific model-types.   I got one from
the shop for my 5551-NAB and it was designated as  "tested on ....... PS/55 5551-NXB.... ".   There was another model designated  for IBM PC Master 100 and such.  These kits were cosmetically  all same.
The shop did some tric or magic ot  their products.  Because I didn't know much about IBM products and model numbers of  PS/55s,  I really worried if the kit for NXB might suitable for my NAB or not. 

Now I really feel strange  that all of my interposers I had bought very cheep or got free in as-is condition  or as  "junk" not knowing about their specification worked fine on my PS/55s. 

By the way, in Japan we commonly refer interposer as  "GETA". GETA means Japanese wooden made sandals.  That's way I put it on the index.

Don't know correct name of this product.  I think  this one was contained in a CPU upgrade kit sold  by JC world, one of famous PC upgrade shop back in '97, but not so sure.  
There were similar kind of interposers which looked like very close to each other back in those days.   I got mine to upgrade my 5551-NAB and I am not sure if this is the one or not. 

   4x/3x/2x capable,  Intel/AMD( dx4)  selectable,  3.3/3.45 selectable.
   No jumper block for WB/WT 


Top View

Bottom View  

am5x86/Fan on DX4/2 

      Jumper Block
       J1: Multiplier for Intel CPU ( but including AMD 5x86 and Cyrix5x86 )
            1-2 for 2x and 4x,  2-3 for  2.5X,  open for 3x

       J2: Multiplier for AMD DX4-80/100
            1-2  for 2x ,  off ...dunno have no  AMD486-120

       J3: Voltage select
            1-2 for 3.45V,   2-3 for 3.30V 

EverGreen 586
Once sold by Evergreen together with Cyrix5x86 100/4x, 133/4x .
A Japanese dealer sold it together with cache driver programs for
   1) Windows95,  
   2) DOS/Win3.1 and OS2 ( Ver. unknown but most possibly Warp3 ).
   Seems et9603.exe by EverGreen contains same drivers set. 

4x/3x/2x selectable,  WT/CB( Cache Back?) selectable,  Will fit both on OD/Main socket.

Mine was given to me as-is condition, most of the outer pins were bent. When I straighten pins,
4 pins around the corner were torn off !!  Yo can see my poor soldering work in the picture.
Due to this soldering rework. I can't use this one on LIF sockets on complexes( any type but of course except  Y ),  on Bermuda or on 9585.

Top View  Bottom View  Cyric5x86-100/4x and EG Fan

      Jumper Block
        3 pin block beside DC conecter for a fan ; Clock multiplier:
        Set jumper as designated on the PCB

       3 pin block in the middle position ;  Cache back setting.
        CB for W/B cache  and W/T for Write-through 

       3 pin block at  the corner ( opposite to pin #1 ); Socket type select: 
       OD for Overdrive socket and the other for standard ZIF or main socket.

EverGreen /am5x86 QFP
am5x86-133 QFP package is soldered onthe PCB.
4x/3x speed selectable, WB/WT selectable, socket position selectable for Normal/Overdrive.

Jumper block from left to righ
    Left ; Socket type select: 
            OD for Overdrive socket and the other for standard ZIF 
            or main socket.
    Center; Clock multiplier:  left-center for 3x,  center -right for 4x
    Right  ;  L1 Cahce status, left-center for  WT, center -right for WB


PowerLeap PL586

      4x/3x/2x selectable,  WB/WT selectable,  Will fit both on  OD/Main socket.

Top View  Bottom View am5x86 with PL a  heatsink/fan 

   Switch Setting
   DC connector for fan assy is placed on the surface of the PCB.  
   Micro Switch block is placed in the middle of pin side.


Position 1 Position 2 * Position 3
Socket type WB/WT Select Clock Multiplier
( Upper )
Standard or ZIF socket Wright-back        2x,  4x *2
 ( Lower )
O/D or 487SX socket         Wright-through 3x

           *1 Position 2 is ignored for a TI486DX4 and Cyrix 5x876 CPU. 
             WB/WT function selection for the TI486DX4 and Cyrix 5x86 CPU
             is auto-detected by a system BIOS. 
             If your system board doesn't support the WB function ( without a
             socket 3CPU socket ),  the system BIOS will automatically set the
             CPU to to run in WT mode.

           *2 Clock-quadrupled for AMD-5x86-133 and Cyrix6x86-133 or higher.
             Clock-doubled for  Intel/AMD/ST 486DX4-100 and Cyrix5x86-100
             or lower.


PL586 with am5x86 QFP ( newer type )
    Not available now.  

JC World Version of am5x86 QFP


This one is supposed to be a modified version of PL586.  There isn't  any jumper blocks for speed selection or voltage. selection,  This one is fixed to 4x operation.
Special ROM is mounted inside pin block.  JC world made several versions for their products so that their interposers could be used on various systems.  Probably the ROM contains some implement to tease the system ( CPU ID or something like that ? ) so that the Overdrive kit can be used in various systems.
Due to presence of this ROM/Socket, This Overdrive kit  doesn't fit in several systems.
For example,  ZIF socket in 5551-N or LIF socket on Type-4 N can't accept this one.

              Top View

I'm not sure about this interposer.  It's branded as "Buffalo"; known to you as Melco.
Designed to be used on ODP socket with a key pin ( 169 pin PGA  layout. see piture below in the middle ).
I think this one is mainly used for NEC PC98 series PCs.  I don't know how the jumper block works. But so far,  it works on my PS/55s.
asically this is 3x capable interposer but there is unused register block  connected to R17 at the bottom side. It should be possible to remake it to 4x(2x)  capable interposer.
Top View Bottom View Cyrix5x86 GP120/Fan
Jumper Block Setting Hacking.  updated 2002.11.16
If my observation is correct, jumper Blocks JP3 & JP4 should be set in combination of 1-2/1-2 and 2-3/2-3.
This interposer has no Voltage Selection jumpers nor Speed Selection jumper.  
Probably this was designed to  use an Intel DX4-100 and other 5x86 CPUs  for 
 1)   system which has only one ( MAIN ) socket ( doesn't matter if it is a
      169-pin socket or 168-pin socket ) 

 2)  system which has a soldered QFP SX CPU with an ODP socket. 
JP4 Pin 1  NC
Pin 2 Connected to B14 at PIN side
Pin 3  Connected to Vss
B14 : UP# ( OUT ) for OverDrive CPU ( ODP )
        UP# ( IN    ) for SX QFP & DX/DX2/DX4 
JP3 Pin 1  Connected to C14 at PIN side
Pin 2  Connected to C14 at CPU side
Pin 3  Connected to A13 at PIN side
  C14 : FERR#  for DX/DX2/DX4
  A13 : FERR#  for ODP
 Jumper settings ( my presumption )
 CPU  JP3  JP4  CPU layout & Socket Type
 CxDX4, 5x86 
 Pins 1-2 Closed  Pins 1-2 closed   Main without SX CPU
 Pins 2-3 Closed  Pins 2-3 Closed  ODP Socket with a QFP SX


ACE 486
This one is very simple.  Really wondered if it could handle 5x86 CPUs but it does.
Basically this is 3x capable unit.  But it is easy to remake it 4x operation with a simple soldering rework. 
Top View  Bottom View am5x86/heatsink/fan
Green rework wire observed in the pics is not for 4x speed. It's for ODPR CPU to be set in ODP socket.   B14(UP#) was connected to Vss.  Then  A13 should be connected to C14 but I left it undone( I noticed  most of PS/55 ODP socket can take ODPR thus the rework was not completed  ).

4x rework can be observed in middle pic.  R17 connection to Vcc  was disconnected and rewired to Vss. ( usually R17 is left open for  3x operation and  is internally pulled up within CPU )
   Click here for enlarged pic in 77KB jpeg.


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