Ardent Tool of Capitalism

Type 4 "Y" Processor Complex

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)

194-360 IBM PS/2 90MHz Processor Upgrade Option with Pentium Technology

Upgrading the P90 Complex

"Y" / Upgrade Pentium 90 MHz
   "Y" Complex Front
   "Y" Complex Back
"Q" vs "Y" Comparison
Memory supported, cache
Complex with no CPU and/or L2 Cache Controller
178 Error
06H3739 vs. 06H7095
Upgrade Information

"Y" / Upgrade Pentium 90 MHz 06H3739, 06H7095, FCC ID ANO6H3729

"Y" Complex Front "CUBRUN"

06H3739 has an early Pentium with the FDIV bug. 06H7095 comes with a fixed processor.

U23 10G3441 C5C/C8C to SSC data iface. May be yellow or blue with exposed die or with a ceramic heat spreader. Peter has seen a metal capped one. No known issues with any variant.
U24 50G8192 (older?) or 8190587 (newer?). The 8190587 is only seen on the "Y" complex. Not sure if there are internal differences or it is just a part number format change.
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. (The "U25" designator is hidden under the heatsink.)
U75 LT1084CT Adjustable Voltage Regulator with max. output current 5.0 A. The regulator is set to 3.36 V and supplies Vcore (core voltage) for the Pentium 90 processor and Vcc3 voltage for i82497 Cache Controller and i82492 Cache SRAM chips (i82497 and i82492 are 5 V parts, but I/O buffers interfacing with the processor are 3.3 V biased).
U76 10-bit bus switch - CBT3384 (TI's A variant), Pericom PI5C3384 or equivalent. Together with CR4 creates a level-shifter for the 3.3 V CPU inputs. The diode is used to drop 3384's supply voltage by 0.6-0.7 V which in turn limits the logic high voltage to the range required by the CPU. Some manufactures offered a "level-shifter" variant of the 3384 chip with the diode already integrated — e.g. TI 74CBTD3384.

"Y" Complex Back "CUBRUN", "THE DELIVERY BOYS", "YELLER DAWGS"

U3,5 The Flash ROM chips are AMD Am29F010-120JC (128 KB, 5V Vpp).
Note: This complex can program 5V parts only, as it doesn't have a local 12 V Vpp generator.

"Q" vs "Y" Comparison (by Major Tom)

The "Y" PCB is based on the revised Type 4 "Q" layout. The differences between the two boards are fairly minimal — even the trace routing remained largely identical outside of the CPU area.

Obviously, the original PGA CPU socket (Socket 4) used by the P5 chips was replaced with a slightly smaller SPGA part (Socket 5) employed by the P54C CPUs. The inner-layer power island underneath the CPU (3.3 V here) was extended to cover the newly defined Vcc3 pins of the revised C5C'/C8C' cache chipset. The unpopulated VRM area (RE1) to the right of the CPU was replaced with a 3-pin low-dropout regulator (U75). Additionally, a 10-bit bus switch (U76) and a discrete diode (CR4) were added to create a level-shifter for the few non-C5C'/C8C' CPU inputs signals. This was necessary because the I/O is no longer 5 V-tolerant on the P54C CPUs. The only exception is the CLK input that is connected directly to IBM's 5 V clock driver chip (U13).

Aside from this, there are only some very minor layout changes, mostly related to bypass caps and other passives.

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 90)
   L2: 256 KB write-back

Complex with no CPU and/or L2 Cache Controller

Look for a non-FDIV P90 HERE.
S-Spec numbers for 90 MHz Pentium CPUs affected by FDIV-Bug:
P54-90 [A80502-90]: Q0542, Q0543, Q0611, Q0612, Q0613, Q0628, SX679, SX874, SX885, SX909, SX921, SX922, SX923, SX942, SX943, SX944, SZ951

Look for an A82497-60 Cache controller. A82497-66 works just as well...

178 POST Error

Laust Brock-Nannestad cried:
   I managed to get hold of one of the much sought after P90 complexes (FRU 06H7095), but when I put it in my 9595A (replacing a P66 complex), it gives me error 0001 7800 and halts.

God Emperor of Microchannel replies:
   Flash to 05 or higher. The update flash disk doesn't depend on any level of refdisk in order to work.

Laust does cartwheels and says:
   Success! This was exactly what I did. I booted the 8595 with the flash disk and it proceeded with the upgrade. Upon the next reboot, I got the friendly IBM SurePath boot screen and then errors about the invalid complex (which were at this point, to be expected). Configured with the Ref disk, rebooted.

Everything was fine. Then I put the complex back in the 9595A and it booted, completing POST for the first time. After reconfiguring, the machine now boots like normal (and the 90MHz on the front looks rather sweet ;-) Next is adding back the cards (It's currently stripped down to just the XGA-2 and processor complex), but it seems to be working OK.

Oh yeah, QCONFIG told me the old BIOS revision level was 03.

06H3739 vs. 06H7095

There are two FRUs for the P90 complex. If you go to the EPRM it says:

(wrong Pentium® 90MHz Processor Card !) - 06H3739
Pentium® 90MHz Processor Card - 06H7095

Oliver Schweizer said:
   I once called the spare part hot line and they told me that the 06H7095 is intended just as a replacement for a crashed complex. According to them the number change came because the original complex could contain the bug-ish P90 and the replacement unit not. If I remember correctly they asked about $ 1500-2000 for the 06H3739! A real tempting offer ;), but after weeks of sleepless nights I decided to stick with my Type 2 complex (and got the Pentium power now for about 5% of that price).

Upgrade Information

Please see the Upgrading the P90 Complex page.