IRTCxxxx does have separate code and data spaces as it is compiling for the AVR.
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 and C,-T.
ZH r31
Scratch ZREG Scratch, IJMP
ZL r30
DPH r29
DP YREG Data Stack Pointer
DPL r28
TOSH r27
TOS XREG Top Stack Item
TOSL r26
SECH r25
SEC Intermediate Second Stack Item
SECL r24
UPH r23
UP USER Pointer
UPL r22
N+5 r21
Scratch
N+4 r20
N+3 r19
Scratch
N+2 r18
N+1 r17
Scratch
N r16