"N" 486DX2 66/33 MHz 61G2343
"P" Pentium 60 MHz  52G9362
"Q" Pentium 66 MHz   92F0120
"Y" / Upgrade Pentium 90/60 MHz   06H3739

Memory supported, cache, features 
Support for Convenience Partition on >3.94GB Drives
Synchrostream Chips
BIOS releases
    Flash BIOS 05 from BIOS 03 or less
    BIOS Level Revison Features
FDIV Replacement
Diagnostic LEDs
Flash ROM Bank (JMP5)
Serial Link (J5)
Serial Data Link (J3)
"Bad" Memory Reported in Same Positions

>Does this also apply to the P90 complex as well?
   I don't think so. I guess they can be found on very early versions only- if ever. I don't think that the "silver capped" version was intended for general marketing. The chip itself looked a lot like a lab proto. Usually the "silver capped" chips have the pins undersides in a sort of PGA arrangement with IBMs' patented ball-contact soldering - the SSC is a SMD ship with very dense pins along the sides. The IBM ESD cap there wasn't a can like usually, but more a shield only glued on top of the ceramic chip carrier. Had the usual engraved lettering with IBM ESD54 {7-digit P/N} {date of mfg/sequence number}.

The God Emperor speaks: 
   I got a P90 complex from Ralph Plewe up in Canada and it had a ceramic SSC. Tested fine with advanced diagnostics. I have also had a P60 or P66 with a yellow SSC.

Flash Bios 10   Resolves an ABIOS time/date defect for OS/2 ONLY.
Flash BIOS 09 Seems to have an OS/2 bug. Not on PCBBS anymore...
Flash Bios 08
Flash BIOS 05
Flash BIOS 02

   Got a 8595-OKD that came with a Type 4 (P60) complex. Every time I start it up, Win 95 comes up with the 1980 date. I can take the ref disk and use "Set Time and Date" and it will show the correct day and month, but the year will be 2799. Is that Y2K complient or what? You can change the date and exit back to the Main Menu, then go right back in Set Date and Time and it is back to the "2799" thing. It has revsion 08 bios. Any ideas?
   Level 10 cured the problem. It seems Win 95, at least SR2, has the same date problem as OS2 when upgrading a 8595 Type 1 or 2 complex to a Type 4 (P60/66).

BIOS 09 Trivia
   If BIOS revision 9 is being used in a OS/2 system, the system date is required to correct manually every time the system is shutdown and restarted during the year of 1999. It works fine in year 2000 and beyond. Use the System Setup utility to set the correct date.

  Details:  A defect in the ABIOS within BIOS 8 and 9 could cause invalid system date when boot to OS/2; the defect is caused by mis-handling of Real Time Clock register's information, and it affects only OS/2. Update to BIOS 10 will fix the problem. Although it's not required, BIOS 10 can be installed in systems using other supported operating systems beside OS/2.

Flashing to BIOS 5 and up from 03 or Lower
   If you need to flash a complex, you can use either 08 or 10. You do not need to configure the complex with a refdisk before flashing it. Boot with the BIOS update disk, flash it, and when the update is complete, you can use the latest refdisk and diags disk to configure the system.

>Peter, whatthehell is each level bios actually supposed to fix?

  Ugh ... have some trouble to recall the changes.
      The earlier levels (prior to 03) were designed for the original P60 / P66 and "enhanced 486DX2" Type 4 platforms. 
   Level 00 / 01 was the first shipment level but had some trouble with the SCSI adapters (F/W SCSI-2 and Server 95 Raid), especially under OS/2.
   Supports 16MB Memory SIMMs
    Level 02 (rel. 02-23-94) was a first "quick & dirty" attempt to fix it - which was not that successful. 
   Added support for 32MB ECC SIMMs.
     Level 03 (rel. 09-15-94) finally got it, but had other trouble (cannot remember). OS/2 2.0 required new IBM2SCSI.ADD and DELIVERY.SYS for support of the Server 95-Raid adapter. Older IBM2SCSI trap the system if used with Level 03 and above (no longer a topic anyways  ). This level adds Fast/Wide SCSI-2 support within the OS/2 drivers.
   3.00 Note:  requires Refdisk ver 1.31 and Diags  version 2.31+.
Supports the 90MHZ complex, FRU P/N06H3739, for 9595 & 8641 and CD-ROMs as a bootable device.
     Level 04 (rel. 02-28-95) was supposed to fix all Raid-, Time/Date-, FDD and CD-ROM (boot) problems under OS/2 - but had a major problem with the memory - was withdrawn and replaced against Level 05 within a month. 
     Level 05 (called "Version 1.24 Level 05", rel. 03-22-95) had major changes, especially for OS/2 2.x and required a new, later reference / diags disk version. Level 05 was the first level to support the Y complex  regularly. (previous levels might display wrong cpu info in diags / setup).
Note: requires Refdisk ver 1.33 / Diags ver 2.32 +.

Supports 4 GB hardfile, Enables the VPD  to display the processor ID and Step level (shows if a Pentium processor with the FDIV fix is installed). Allows disabling of the error reporting log POST error which is useful during RIPL under some conditions.

Resolves the following problems:
Bootable CD-ROM attached to the RAID controller, with an additional non-RAID SCSI adapter installed.  diagnostic problems related to the CD-ROM being attached to the RAID controller. running SCSI fixed disk diagnostics with the "read verify" option selected.
     Level 06 Never seen. Either not issued or superseeded before release.
     Level 07 (rel. 10-27-95) ... no idea. Has been an intermediate release May have contained a "work-around" for the P90 FPU-bug (not sure). 

BIOS code was added to support switching a single keyboard and monitor between multiple systems.
      Level 08 (rel. 01-16-96) came to fix "various problems" with the P90 platform and the IBM Fast / Wide Streaming Raid Adapter /A - which came with the Server 500. Level 08 was mainly intended to be used with the 8641 (Server 500) only, since the F/W-SR was not generally announced for the 9595A (but works though - the number of drives however was limited to 3 due to power- and heat-problems).
      The Level 08 might have various sublevels (avoided to write "subversions" ... some people might get that wrong :-) ), which differ by date of announcement but aren't explained anywhere. Most likely they fix some typo-errors / different language support.
       Level 09 (rel. -funny-  01-16-96 still) now - as it seems - is the last Level 08 with integrated Y2K rollover fix. Rem.: The (rel. mm-dd-yy) refers on the date the $000x000.IML files have.
       Level 10 Resolves an ABIOS time/date defect for OS/2 ONLY.  But-. It seems Win 95, at least SR2, has the same date problem as OS2 when upgrading a 8595 Type 1 or 2 complex to a Type 4 (P60/66). 

        Would say that Level 05 was the first BIOS that really worked. If your machine has a downlevel BIOS - use at least 05 if you have an IBM Fast/Wide SCSI-2 Adapter /A or the IBM SCSI adapter with cache /A. If your machine has the Server95-RAID adapter /A (codename "Passplay" without external port) or the IBM Fast/Wide Streaming Raid Adapter /A (codename "Cheetah" with external port) you should have Level 08. 

Flash ROM Bank (J5)

      This jumper on the processor complex is used to select which bank of flash memory is accessed as ROM. The ROM subsystem consists of 256KB of flash memory in two banks of 128KB. If the jumper is in position 0 when the system is powered on, bank A is mapped to addresses hex 000E0000 to 000FFFFF and hex FFFE0000 to FFFFFFFF.  The system is shipped with the jumper in position 0 (bank A selected). 

Note: Don't move jumper while system is powered-on; unpredictable operation will occur. 

Access to ROM or RAM at address space hex 000E0000 to 000FFFFF is controlled by the bits in the memory controller registers. When ROM is enabled, it is not parity checked. If the jumper is in position 1, bank B is mapped to these addresses. 
 

Peter said:
   Originally planned for a sort of "emergency mode". Once you screwed up the Flash-BIOS you could toggle the bank, insert any working flash update in the FDD A: and restart the  machine, which takes the flash-image from the floppy drive and recovers (as it can be done on the 704 in the "Bios recovery mode"). However: the base boot-BIOS lacked the required routines to delete the loused up bank of the Flash-ROM ... and as far as I know the loading of an image from Floppy  does not work. Another useless feature.

Serial Link (J5)
   Serial Link Intended for use with an earlier system management adapter, which didn't made it to the salesroom. The idea was to supply a sort of status-link to the processorboard and the  SCSI- adapter(s) and the (possible) backplanes on the later servers. 

July 1994      ... IBM TECHNICAL DISCLOSURE BULLETIN 
Personal Computer Processor Upgrading

Serial Diagnostics Link
Nov. 1994      ... IBM TECHNICAL DISCLOSURE BULLETIN
Serial Diagnostic Link for PS/2 Model 95 Processor  Cards 
  Disclosed is a Serial Diagnostic Link (SDL) for the PS/2* Model 90 and 95 information panel, allowing the main system processor direct access to the alphanumeric display. This display is used during Power-On Self-Test and during error conditions, as information regarding the execution of the processor is reported to the user. With the SDL, the main processor does not have to rely on the operational condition of any other system function to display information on the alphanumeric display.
    Without the SDL, the Model 95 information panel interface can be used by the main processor only when the Micro Channel*, the planar board VLSI, and the processor complex card interface are the functional. The SDL is a three-signal interface. Output signals from the processor card, which are input signals to the information panel used to program the alphanumeric display, are DISPLAY_STROBE, and DISPLAY_RESET. The DISPLAY_SENSE signal is an input to the
processor card from the information panel, which is the logical NOT of the DISPLAY_STROBE. The DISPLAY_SENSE signal is used by the processor to determine the presence of the SDL and to provide a real-time mechanism for monitoring the SDL itself. The interface is operated in a uni-directional mode, with all information emanating from the processor card. 

  Fig. 1 is a schematic diagram showing the address/write contol logic and the read back latch used to provide this function. 
   Fig. 2 is a schematic diagram showing the data deserializer used to provide this function.

   The support hardware on the processor card and on the information panel for this function is minimal. On the processor card, this logic provides two bits in an I/O WRITE port, corresponding to the DISPLAY_STROBE and DISPLAY_RESET signals, and one bit in an I/O READ port, corresponding to the DISPLAY_SENSE signal. The operation of these signals by the processor is done entirely with software. On the display panel, logic transforms the incoming SDL bit stream into the existing parallel interrace to remain compatible with the alphanumeric display. 

   Fig. 3 is a timing chart showing the timing of each signal to display a character on the alphanumeric display. The duration of signal levels for this interface are defined only by minimums. Since these minimums are less than the times available in processor card bus cycles, in effect
these signals are timing-independent. No clocking mechanisms are required for this interface.  While the timing of the signals is thus independent, the sequence of their operation is not. 
   As shown in Fig. 2, five stages must be performed in the following order---initial, count/latch, validate/reset, write character, and validate/hold. The initial stage is entered on a high-to-low transition of the DISPLAY_RESET signal. The state of DISPLAY_STROBE is a "don't care" condition when entering this stage. Upon entering this stage, all logic on the information panel and processor card is reset, awaiting the transmission of the output character information. The count/latch stage is entered when the processor produces a high-to-low transition of the DISPLAY_STROBE signal. In this stage, every high-to-low transition is considered a "count," and every low-to-high transition is considered a "latch." The logic on the information panel sequences the "counts" through a 74F393 ripple counter, the outputs of which are defined as the parallel interface signals necessary to operate the alphanumeric display. In this way, a simple serial to parallel interface conversion is performed by the ripple counter. The "latch" is used to latch the previous parallel output of the ripple counter into a 74F373 register, so that the ripple counter may be reset in the next stage without destroying the "count" data. 
    The write character stage is entered on a high-to-low transition of DISPLAY_STROBE while DISPLAY_RESET is high. Upon entering this stage, the data is written to the display, and a character appears at the correct address location. The validate/hold stage is entered on the
low-to-high transition of the DISPLAY_STROBE signal while DISPLAY_RESET is high. Upon entering this stage, the data is written to the display, and a character appears at the correct address location. The initial stage is re-entered from the validate/hold stage by the high-to-low transition of the DISPLAY_RESET signal. At this point, the SDL and information panel are ready for the next output character. 

   Programming, by the system code, for the stages described above is straightforward. The following pseudo code shows the general flow of the stages, with character data values necessary to display ASCII characters at each address location of the alphanumeric display: 
Ed. Not cleaned up, see link to original article!

 OUT DISPLAY_STROBE,1   ; Power on reset
 OUT DISPLAY_RESET,1    ; These three statements are done at first power
 OUT DISPLAY_RESET,0    ; on to get into the initial stage
 TOP:
 Move CX, Character     ; place the data to be displayed in a
 Begin:                 ; decrement register.  Enter Count/Latch 
                        ; stage first time thru loop.
 OUT DISPLAY_STROBE,0   ; Provide a "count"
 OUT DISPLAY_STROBE,1   ; Provide a "latch"
 LOOP Begin             ; Decrement the data, loop until done.
 OUT DISPLAY_RESET,1    ; Enter validate/reset stage
 OUT DISPLAY_STROBE,0   ; Enter write character stage
 OUT DISPLAY_STROBE,1   ; Enter validate/hold stage
 OUT DISPLAY_RESET,O    ; Enter initial stage
 ; Go to TOP to output the next character.

Peter has a flashback and says-
   Sounds odd - but ... replace the CMOS buffer battery. And toggle the "Clear Power On Password" Jumper once when you do that. Pull out the battery, wait at least 20 minutes, toggle the jumper, install the new battery and fire the thing up - reconfigure ... and .... ??? 
   I had exactly the same problem back in the mid-90s when I upgraded an 8595-AKD with a T4 P60 platform. Occasional memory errors always on the same memory connectors. We'd sprayed them - we swapped and replaced memory modules (which ran fine in e.g. a 9577 afterwards) - we did everything you could think of.
   Then we replaced the CMOS battery (that CR-2032 3V lithium cell) ... and the error disappeared. Unexplainable otherwise and not logical.