I looked into two approaches with getting more memory into the Audrey, using DIMMs and removing the existing chips and replacing with them with larger ones.
This approach would be very difficult, because I have found that the you can not simply solder wires/leads from the exiting oins/CPU to the DIMMs. They length of the wires/leads from the CPU to the DIMM is very important, because timing is very critial for memory.
Note, one reason why you can pop in many different memory DIMM configurations into a DIMM slot, is because the parameters or config data in located in an EEPROM on the DIMM memory board with the SDRAM chips. This includes CAS, RAS, and memory size among others. In the case of the Audrey, these settings are hard coded in the IPL and the memory controller is configured by the IPL code.
Replacing the memory chips:
Replacing the memmory chips with larger ones seems more promising. I will do this soon. However, I'm not sure we can get any larger than 64 MBytes total. Its seems that chips larger than this have a 8K refresh size which is not compatible with the 4K refresh of the Audrey. But, I'm not sure about this, so I'll have to try it after I do an Audrey with 64 Mbytes.
The IPL code in the Audrey tells the memory controller how much memory there is in the system. I do not believe this is set in QNX OS. There is a way to set different values in the memory controller registers, this includes the memory size. So, after IPL, the first thing I'll do is tell the memory controller that there are 64 Mbytes. But, this may be too late, because QNX may have already queried the memory size. So, I may have the use the solution SafariJack noted above.
I am also concerned about the amount/type of memory you can put on the Audrey. Because next to the memory chips, I believe are the Row and Column decoders. These chips are associated with the memory but I don't know how. Does anybody know? They are also present on DIMMs modules as well.
You mention you used Micron memory chips. Do you have the part num by any chance? Have you tried larger memory sizes? Where's a good place to get memory chips? Most places don't sell by the chip, but by the DIMM.