 Most Forth systems include an assembler that allows one to specify words using the processor 's facilities at its lowest level . Mostly the assembler is tucked away in a separate namespace ( wordlist ) as relatively few users want to use it . Forth assemblers may use a reverse @-@ polish syntax in which the parameters of an instruction precede the instruction , but designs vary widely and are specific to the Forth implementation . A typical reverse @-@ polish assembler prepares the operands on the stack and have the mnemonic copy the whole instruction into memory as the last step . A Forth assembler is by nature a macro assembler , so that it is easy to define an alias for registers according to their role in the Forth system : e.g. " datastackpointer " for the register used as a stack pointer . 
