uae_a3000mem_size

The option documentation is properly formatted yet

Description: Size in megabytes of motherboard fast memory Default: Range: 0 - 65536 Type: integer

A3000 and A4000 models use 8MB of motherboard fast memory by default.

Implementation: UAE code refers to this as mbresmem_low_size.

Code:

if c.uae_a3000mem_size.explicit:
    value = c.uae_a3000mem_size.explicit
elif c.motherboard_ram != "":
    value = str(int(c.motherboard_ram) // 1024)
# elif c.int_model == "A3000":
#     value = "8"
# elif c.int_model == "A4000":
#     # FIXME: should PPC / OS4 models be excluded?
#     value = "8"
else:
    value = "0"

Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/uae_a3000mem_size