3.4.2 Z80/Z180 Storage Class Language Extensions

3.4.2.1 sfr (in/out to 8-bit addresses)

The Z80 family has separate address spaces for memory and input/output memory. I/O memory is accessed with special instructions, e.g.:

sfr at 0x78 IoPort;  /* define a var in I/O space at 78h called IoPort */

Writing 0x01 to this variable generates the assembly code:

3E 01      ld a,#0x01 
D3 78      out (_IoPort),a

3.4.2.2 banked sfr (in/out to 16-bit addresses)

The keyword banked is used to support 16 bit addresses in I/O memory e.g.:

sfr banked at 0x123 IoPort;

Writing 0x01 to this variable generates the assembly code:

01 23 01   ld bc,#_IoPort 
3E 01      ld a,#0x01  
ED 79      out (c),a

3.4.2.3 sfr (in0/out0 to 8 bit addresses on Z180/HD64180)

The compiler option --portmode=180 (80) and a compiler #pragma portmode z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructions in0/out0 instead of in/out. If you include the file z180.h this will be set automatically.