Google

PFE-SYSTEM system words - mostly posix

This file exports a set of system words for a posixish OS environment. So should do any alternative wordset you might create for your OS.

CALL-C  

accessing shared libraries - only available for i386-linux

reference: p4_call_c in ../src/unix.c:0427, export CO CALL-C

USELIBRARY  

accessing shared libraries - only available for i386-linux

reference: p4_uselibrary in ../src/unix.c:0369, export CO USELIBRARY

(LOADM) ( bstring -- sucess )  

reference: p4_loadm2 in ../src/unix.c:0783, export CO (LOADM)

LOADM filename ( -- )  

dlmap the shared object (or share an already mapped object) and run the per-thread initialization code. This is the user-convenient function, otherwise use (LOADM) 
 simulate:
   : LOADM  BL WORD 
     HERE (LOADM)  0= IF ." -- load failed: " HERE COUNT TYPE CR THEN ;

reference: p4_loadm in ../src/unix.c:0819, export CO LOADM

DLSYM symbolname ( -- address )   exec-only
immediate
lookup the symbol that follows and leave the address (or null)

reference: p4_dlsym in ../src/unix.c:0832, export CI DLSYM

DLCALL
immediate

no forth documentation available   (p4_dlcall)

reference: p4_dlcall in ../src/unix.c:0857, export CI DLCALL

#! ... ( -- )  

ignores the rest of the line, defining `#!' is used to support forth scripts executed by the unix kernel

reference: p4_ignore_line in ../src/unix.c:0892, export CO #!

CLOCK ( --- ticks )  

return clock()

reference: clock in ../src/unix.c:0903, export CO CLOCK

CLK_TCK  
constant
CLOCKS_PER_SEC - usually one million ticks, but can be very different on a specific system. Exported as a constant. see CLOCK

reference: CLK_TCK in ../src/unix.c:0037, export OC CLK_TCK