See the Microchip documentation for differences in devices.
IRTCxxxx does have separate code and data spaces as it is compiling for the PIC18F.
The words C@, C!, @, !, 2@, 2!, FILL, ERASE, BLANK, CMOVE, ACQUIRE and RELINQUISH operate on the RAM space. But the code memory space uses MC@, M@, ,-T , C,-T .
$00D, $010 Scratch N
FSR0 DP Data Stack Pointer
$000, $001 TOS Top Stack Item
FSR1 UP USER Pointer
$004, $005 RP Forth Return Stack Pointer