Still looking for information on this card! Tell ME! 
@7FAE.ADF - XTEND Renaissance Expansion Board - CPU Upgr. 
C7FAE.ADF - Init file for @7FAE.ADF 

I am guessing that the memory supported is 1, 2, and 4MB SIMMs. Remember, the 50Z was a 286 system- max addressable memory would be 16MB. 

486SLC Daughter Card                                         CPU "Flex Cable"

P/N 301-128919  Side View

JP1-JP3, JP5 Headers to Base JP4  60 pin header to flex cable  U13, U14 BIOS?

U19 TI TX486SLC (25MHz?)  U24 68 pin PLCC socket (Co-pro?)

   I have the tape "CPU flex cable" that fits JP4. It extends towards the rear of the adapter, where it connects to a PLCC header that fits into the 50Z Type 2 board's CPU socket. 

From Frank Sawchuck
   The XTend card works with the 16 bit bus of the Model 50Z, but it also doubles as a 16 bit memory only card or a 32 bit memory only card with the 486 daughter card removed The 486 upgrade cpu complex is a optional XTend daughter card  for the main XTend board. I hope that I'm making sense, anyway it is a card that I've used in the 50Z as a cpu / memory upgrade and on 386 and 486 IBM models as a memory only upgrade card. 

From Xtend's Utility Disk
The Renaissance System upgrage significantly accelerates the CPU functions, including accesses to main memory and to the motherboard resources  (unlike CPU-only modules). 

Some of the older 286 PS/2 models may experience problems with some software due to the processor outrunning motherboard peripherals.  If you are experiencing unusual behavior with your system, the following utility programs will help you identify whether the problem is speed-related by changing the speed of the 486SLC processor. 

ARB.COM     - slows down the processor's cache 
OFF.COM     - turns off the processor's cache 
ON.COM      - turns the cache back on (it is always on after boot-up) 
ENSRVR.COM  - run this before running the Novell SERVER 

If you want the zip file, talk to ME! 

Onboard ROM Location
   If a Renaissance CPU upgrade is installed, select <Segment C000>, otherwise select <ROM Disabled>. 
         <Segment C000-C1FF>,  Segment C800-C9FF, Segment D000-D1FF, Segment D800-D9FF, ROM Disabled