The only model supported is Flat 24.
This generates code for the 24 bit contiguous addressing mode of the
Dallas DS80C390 part. In this mode, up to four meg of external RAM
or code space can be directly addressed. See the data sheets at www.dalsemi.com
for further information on this part.
Note that the compiler does not generate any code to place the processor
into 24 bitmode (although tinibios in the ds390 libraries will
do that for you). If you don't use tinibios,
the boot loader or similar code must ensure that the processor is
in 24 bit contiguous addressing mode before calling the SDCC startup
code.
Like the --model-large option, variables will by default
be placed into the XDATA segment.
Segments may be placed anywhere in the 4 meg address space using the
usual --*-loc options. Note that if any segments are located
above 64K, the -r flag must be passed to the linker to generate the
proper segment relocations, and the Intel HEX output format must be
used. The -r flag can be passed to the linker by using the option
-Wl-r on the SDCC command line. However, currently the linker
can not handle code segments > 64k.