The BIOS 1.20L from 1993 works in the REV-C modell as I tested.  
With the 1.20L your 1522 will work with HDs greater 1GB. The first bios 
don't recognize them even you set the Jumper -R for >1GB.

AHA-1522A_REV-C_Bios100_1990#1.eprj
AHA-1522A_REV-C_Bios100_1990_V1.4#3.eprj
AHA-1522A_REV-D_Bios120L_1993_V1.20L#2.eprj

The *.eprj is a zipped file for my ELNEC memprog. Please extract the *.bin for 
use it with any other epromer than from ELNEC.