rf90954a.exe Reference Disk Type 4 Processor Complex v1.34 (zipped image)
rd9095a.exe Diagnostic Disk Type 1 - 4 Processor Complex v2.33 (zipped image)

Pictorial of failed Type 4 P60/P66 upgrades (by Tam Pham)

"P" & "Q" / Upgrade Pentium 60 MHz & 66 MHz
   "P" & "Q" Complex Front (old)
   "P" & "Q" Complex Back (old)
   "Q" Complex Front (new)
   "Q" Complex Back (new)
Memory supported, cache
Complex with no CPU and/or L2 Cache Controller
496 vs. 497 Cache Controller
Intel Pentium Overdrive 133 MHz (POD133/120)
Possible Q Upgrade Success!

"P" / Upgrade Pentium 60 MHz (old) (52G9362, 06H7324, FCC ID ANOIBM586A60)
"Q" / Upgrade Pentium 66 MHz (old) (92F0120, 06H7317, FCC ID ANOIBM586A66)

"P" & "Q" Complex Front (old)

52G9362 and 92F0120 have an early Pentium with the FDIV bug.
06H7324 and 06H7317 come with a fixed processor.

U23 10G3441 Memory Bus Controller? - may be yellow (early) or blue (later). Louis has a ceramic version and Peter has seen a metal capped one.
U25 LT1085CT Adjustable Voltage Regulator with max. output current 3.0 A. The regulator is set to 3.7 (3.75) V and powers the SynchroStream Controller.

"P" & "Q" Complex Back (old)

U70, CR3, L1 (plus some other passives) are part of a local 12 V voltage generator. This additional "programming voltage" (Vpp) is required by the Flash memory to perform erase/write operations. Its general topology closely replicates the "Flash Memory VPP Generator" circuit from the LT1109 datasheet (page 1). A local 12 V generator is necessary because the processor complex is supplied with 5 V only.

"Q" Complex Front (new)

92F0120 has an early Pentium with the FDIV bug. 06H7317 comes with a fixed processor.

Revised layout similar to the later "Y" complex. It's possible that this layout was used for some later 60 MHz "P" boards as well, but this has to be yet confirmed.

RE1 Unpopulated, purpose unknown. Maybe for a component that used four mounting posts to match the pattern. The right pair have thick PCB traces going to them. Maybe a VRM?
U23 10G3441 Memory Bus Controller? - may be yellow (early) or blue (later). Louis has a ceramic version and Peter has seen a metal capped one.
U25 LT1085CT Adjustable Voltage Regulator with max. output current 3.0 A. The regulator is set to 3.7 (3.75) V and powers the SynchroStream Controller.

"Q" Complex Back (new)

Memory

RAM:
   PS/2 72-pin SIMMs, ECC or Parity, 70 ns Presence Detect
   Min/Max on system board: 8/64 MB Parity, 8/256 MB ECC

ROM:
   256 KB (2 x 128 KB) Flash ROM

Cache:
   L1: 16 KB (Pentium 60/66)
   L2: 256 KB write-back

Complex with no CPU and/or L2 Cache Controller

"P" Complex

Look for a non-FDIV P60 HERE.
S-Spec numbers for 60 MHz Pentium CPUs affected by FDIV-Bug:
P5-60 [A80501-60]: Q0352, Q0394, Q0400, Q0412, Q0466, SX753, SX835, SZ949
A A80501-66 will work just fine.

Look for an A82496-60 Cache controller. An A82496-66 works just as well...

"Q" Complex

Look for a non-FDIV P66 HERE.
S-Spec numbers for 66MHz Pentium CPUs affected by FDIV-Bug:
P5-66 [A80501-66]: Q0353, Q0395, Q0413, Q0467, SX754, SX837, SZ950

Look for an A82496-66 Cache controller. An A82496-60 may or may not work at 66 MHz.

496 vs. 497 Cache Controller

From Dr. Jim Shorney:
   Overdrive processors are not compatible with the '496 cache controller on the P60/66 complexes. However... I swapped out the '496 cache controller on mine for a borrowed '497 (well heatsinked) and was able to boot DOS with a POD 133 on my P60 (overclocked to 66). It wasn't entirely stable, and would not boot OS/2 Warp 4.0 or NT 4.0. The PowerLeap PL54C interposer was still dead in this configuration. There may yet be hope, I haven't tried the PowerLeap with anything other than an Intel 166 yet, and I may also downclock the complex back to 60 MHz and see what happens. There may yet be hope...

The '497 has some 3.3 V supply pins, but it seemed to run stable and reliable for several hours with the stock P60 CPU in my system in place of the 5 V-only '496. I briefly looked over the docs this afternoon (712 pages, wow...). Seems the '497 is still a 5 V part, it is the I/O buffers that connect to the CPU that are 3.3 V. This probably explains in part why the chip doesn't self-destruct in the '496 socket. It also seems to invalidate the need for an interposer, since the P60/66 I/O is 5 V anyway and the buffers would have to run at 5 V to interface at all with the CPU. This brings up the question of noise immunity, though - will circuits designed to run at 3.3 V logic levels be more or less sensitive to noise or poor signal quality when run at 5 V? Inquiring minds want to know.

From Tony Ingenoso:
   I suspect noise is going to be less of a problem at higher voltages Jim. In theory, the voltage range for correct operation would be wider (particularly for CMOS). The only reason I ever saw (other than laptop applications) for the drive to lower voltages was to limit heat as the gate counts and frequencies went up. CMOS parts like high voltages -- you can crank clock speeds faster with higher voltages(the standard overclockers trick). Discrete type CMOS parts can often be run as high as 20 V and work fine. The downside is that its power characteristics start approaching those of TTL at the higher speeds (and heat goes up). If the only nominally 3.3 V sections of the cache controller are the line drivers/buffers, there's probably not going to be enough stuff getting overvoltaged to make any significant difference in the power draw.

Intel Pentium Overdrive 133 MHz (POD133/120)

From Al Savage:
> So, CPU gurus, will this work in my 8590-OLF w/Type 4 P60?

From Jim Shorney:
   You need to stop skipping the meetings, Al... I just tried this last week, both with and without an Intel EUCD35 interposer. Didn't work. Sometimes would get as far as CP:8, sometimes wouldn't even post. I friend of mine here in Lincoln who doesn't read the NG has also tried it, and he had even less luck then me; his machine wouldn't post at all.

I'm hanging onto my chip, though, in case Tony or someone else comes up with a solution. I suspect timing loops in the BIOS, but I'm neither a programmer nor an engineer...

Cache Controller/CPU Incompatibility
   From the recesses of my mind- Someone tracked down the fact that the POD133 will not work with the cache controller on the P complex, BUT the individual had swapped that cache controller out with another type. I can't find the details...

From Jim Shorney:
   I can answer that: none. Tam Pham discovered in his arcane book of shadow knowledge that the Pentium Overdrive 120/133 is not compatible with the 496 cache controller on that complex. This seems to be the most likely reason that all interposer upgrades to date have failed as well. Many have tried, all have failed. There is a possibility of using a 497(?) cache controller on this complex, but it appears that it may require a voltage interposer of it's own. This prospect is still awaiting investigation (anyone got a spare 497 they can send me?).

From Dennis Smith:
   Jim, I'll let you *borrow* the 82497-60 from my dead P90 complex.Be advised, Tam found out that the 497 has nine pins set for 3.3 V. I ran a 497 in my P60 complex for about a half an hour with no ill effects though.

From Terminaut:
   I dug through craploads of old Intel documents today, and found my notes from Intel (circa '95) for the Pentium Overdrive 133 MHz (POD133/120) processor.

Written in plain ingles, the Intel doc says: "will not support the 82496 Cache Controller and 82491 Cache SRAM chip set". Additionally, the documentation states that the POD133 is designed to support PCI chipsets.

Some other notes:

• IU, IV, and IBT plus have been removed
• branch trace pins (BT[3:0]) have been removed (no execution tracing)
• breakpoint pins (BP[3:0]) have been redefined such that each assertion of one of these pins indicates that 1 to N BP matches occurred, where N =core/bus frequency ratio
• STI/CLI (restore/clear interrupts) are each 2 clocks shorter

Possible Q Upgrade Success

Tim Clarke said:
   Without going into too much analysis as to WHY its working. I have this up and running reliably, so far. Using a T4-P66 complex previously Flashed to BIOS Level 10, an 82497 cache controller from a T4 P90 complex and a stock PODP5V120/133 Overdrive for Socket 4 (Ed. square 21x21, 237pin PGA (pin-grid-array), stop beating me, Tim!))

It threw the odd "1047000 221" error (cache/memory-related?) early in the power-on, auto-reconfigure, set date&time, auto-reboot song and dance but doesn't seem to do that anymore. Maybe there are some devious POS-stored auto-tuned cache-control/memory-access related parameters, but hey, I'm not complaining.

9595 xPx Server 95 (AKA "Server 95 560")

9595-0PT - P60, 16/256 MB (ECC), 1 GB SCSI-2 F/W, 2.88 MB floppy
9595-0PTF - As above - Canadian French
9595-0PV - P60, 16/256 MB (ECC), 2 GB SCSI-2 F/W, 2.88 MB floppy

9595 xPx Server 95 Array Models (called 95A)

9595-3PG - P60, 16/256 MB (ECC), 3 x 540 MB SCSI-2 F/W, 2.88 MB floppy
9595-3PT - P60, 16/256 MB (ECC), 3 x 1 GB SCSI-2 F/W, 2.88 MB floppy

9595 xQx Server 95 (AKA "Server 95 566")

9595-0QT - P66, 16/256 MB (ECC), 1 GB SCSI-2 F/W, 2.88 MB floppy
9595-0QTF - As above - Canadian French
9595-0QV - P66, 16/256 MB (ECC), 2 GB SCSI-2 F/W, 2.88 MB floppy
9595-PQG - Pentium 66, 16/256 MB (ECC), 540 MB SCSI-2 F/W, 2.88 MB floppy
9595-PQT - P66, 16/256 MB (ECC), 1 GB SCSI-2 F/W, 2.88 MB floppy

9595 xQx Server 95 Array Models (Also called 95A)

9595-3QG - P66, 16/256 MB (ECC), 3 x 540 MB SCSI-2 F/W, 2.88 MB floppy
9595-3QT - P66, 16/256 MB (ECC), 3 x 1 GB SCSI-2 F/W, 2.88 MB floppy

Note: Server 95 -PQG & -PQT models came with MGA Ultima Video Graphics Adapter, CD-ROM-II drive, and 3-button mouse