This refers to the command-line tools found in lc3tools/ which include the lc3sim
simulator and the lc3as assembler. lc3as accepts ascii text files
containing LC3 assembly code, eg. foo.asm, and produces LC3 object files, eg.
foo.obj.:
lc3as foo.asm
The simulator loads the .obj files to its simulated memory and simulates
LC3 execution.
NOTE--lc3sim starts up by reading the lc3os.obj operating system code into its
simulated LC3's memory.
The LC3 design specifies that execution starts at x0200 on power on.
The initial OS code would print a message and jump to
x3000 to begin execution of a user program (if one is there; otherwise, begins
executing whatever garbage is there.)
However, the simulator acts as if it has a
breakpoint set at address x0454. It halts execution and issues the simulator's
command prompt. This command-line version of the simulator does not seem to
simulate the display device (but see lcsim-tk).
Commands for lc3sim:
Command Description
------------- ----------------------------
lc3sim ---- start simulator
lc3sim file.obj ---- Load program and start simulator.
lc3sim-tk ---- start graphical simulator.
lc3sim-tk file.obj ---- Load program and start graphical simulator.
h show all commands
quit quit simulator
l LIST words of memory w/ disassembly
l -- from PC
l loc -- from loc = address or loc = label
l loc1 loc2 -- ranging from loc1 to loc2
l more -- from last location displayed (or just hit [RETURN])
t label TRANSLATE a label to its symbol table value,
and show memory contents at that address.
p PRINT register values, and show memory word at PC
r reg val REGISTER assignment: reg <== val.
m addr val MEMORY assignment: Mem[ addr ] <== val.
c CONTINUE execution: start machine cycle running
b BREAKPOINT: manage execution stops
b set loc -- set breakpoint when PC == loc (address or label)
b list -- list all breakpoints
b clear loc -- remove breakpoint at loc
b clear all -- remove all breakpoints
n NEXT execute instruction or subroutine or trap at PC.
s SINGLE-STEP execute single instruction at PC.
f FINISH execution of subroutine or trap, including RET.
d DUMP memory as hex words
d -- from near PC
d loc -- from loc
d loc1 loc2 -- from range
d more -- from last displayed location (or use [RETURN] )
f filename FILE read into memory at loc specified by ".ORIG".
reset RESET LC3 and reload the last file.
execute filename EXECUTE script file.