486 Interposers and Upgrades
AMD 5x86 133 - The whole story (by Jan Steunebrink)
Content created by Sandy. Edited by Major Tom.
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
These interposers usually have jumper blocks for:
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
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 :)
Once sold by Evergreen together with Cyrix5x86 100/4x, 133/4x. A Japanese dealer sold it together with cache driver programs for:
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.
3 pin block beside DC connector for a fan: Clock multiplier
EverGreen 586 Am5x86 QFP
Am5x86-133 QFP package is soldered on the PCB.
4x/3x speed selectable, WB/WT selectable, socket position selectable for Normal/Overdrive.
Left: Socket type select
4x/3x/2x selectable, WB/WT selectable, Will fit both on OD/Main socket.
DC connector for fan assy is placed on the surface of the PCB.
*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.
PowerLeap PL586-133 QFP (manual)
Clock-tripled/quadrupled processor upgrade for 486 systems. A QFP version of the AMD Am5x86-P75 CPU is permanently soldered on the interposer.
JC World 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
I'm not sure about this interposer. It's branded as "Buffalo";
known to you as Melco.
Jumper Block Setting Hacking. updated 2002.11.16
UP# (IN) for SX QFP & DX/DX2/DX4
A13 : FERR# for ODP
Jumper settings (my presumption)
This one is very simple. Really wondered if it could handle 5x86 CPUs but it does.
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). Enlarged picture HERE.
Unknown PGA DX4/2 Interposer
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.
4x/3x/2x capable, Intel/AMD( dx4) selectable, 3.3/3.45 selectable. No jumper block for WB/WT
J1: Multiplier for Intel CPU (but including AMD 5x86 and Cyrix5x86)
Information about the PowerStacker 5x86 Upgrade HERE.
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