70_FLASH.EXE  8570 planar upgrade flash BIOS v1.18.02
rf70plan.exe  8570 planar upgrade reference diskette

486DX and BL2-66 use same system board.

Reply 8570 OEM Planar
32-bit Mode under W95

Two Planar Upgrades Available
486DX 33MHz, Option P/N70G8988 This includes an integrated memory cache controller and Math Co-Processor support.  The clock speed operates at 33MHz for the internal and external operations. 

486BL2 66MHz, Option P/N32G3300   The IBM 486 BL2-66 includes an internal memory cache controller and 16KB memory cache.  The clock speed operates at 66MHz for the internal operations and 33MHz for external operations.

U35-U36 Supports 4MB or 16MB 70ns and 80ns Industry standard SIMMs. Up to 32MB memory support (31MB addressable)

006 Error
 006 error occurs after adding memory to 8570 with either system board upgrade installed:
                     - 486DX 33MHz, Option P/N70G8988
                     - 486BL2 66MHz, Option P/N32G3300

The 8570 upgrade only supports 4MB and 16MB Industry Standard Memory SIMMs.  Memory transferred from previous system board will not function on upgrade boards.

   IBM's 4MB Industry Standard SIMM, Feature Code 7634, Option P/N92G7201 and a 16MB Industry Standard SIMM, Feature Code 2011, Option P/N92G7204 or P/N60G1622. Memory must be identical in size and speed if using both memory SIMM sockets.

   Rich Wolos grabbed a 16MB parity from his Lacuna 77 and it worked fine.

Just to Show this Means Business
Billy Wong wrote:
   BTW I also tried to upgrade the board's 8 megs of RAM (two 4 meg modules are on it already) with the two IBM 8 meg 70ns true parity SIMMs and it gave me the 006 error.

Memory Expansion Adapters Supported
   The following  memory adapters are supported:
o   2-8MB 80386 Memory Expansion Option (#5211, 6450605)
o   Enhanced 80386 Memory Expansion Option 2MB Kit (#3077, 34F3077)
o   Enhanced 80386 Memory Expansion Option 4MB Kit (#3011, 34F3011)
       The PS/2 80386 Memory Expansion Option (6450367) is not supported

33 MHz Clock Source  

Alfred Arnold identifies source of 33MHz:
   You asked where the 33MHz clock is coming from.  I am quite sure they come out of U113.  This is a so-called 'clock synthesizer' chip that typically gets a 14.31818 MHz clock (Y1) as input and uses programmable frequency dividers and multipliers to generate arbitrary output clock frequencies (J13 might be a jumper to select between two frequencies, haven't checked that so far).  Such synthesizers first became popular with Super VGA boards since they needed a lot of different clocks for the different resolutions and you were able to replace half a dozen discrete oscillators with one crystal and such a synthesizer chip.  These days, they're a standard component on every PCI man board.

Standard IDE/ESDI Hard Disk Controller (Change to manual settings)
Basic Config 0
I/O 01F0-01F7
I/O 03F6-03F6
IRQ 14

   This will enable the HDD in 32-bit mode and has also allowed the use of a 4x Toshiba CD-ROM.  To get the floppy to work, install the Standard Floppy Disk Controller after getting the HDD working.  The other thing to note is that the floppy had to be a Sony for me to get it working.

W95 Experiences
Al Brandt sez:
    I loaded mine up with Windows 95 and with the Cirrus Logic video, you can get up to 800x600 at 16-bit color. I don't know if the W95 driver does that, but I know that it at least does 640x480 at 16-bit.