Replace register numbers and key labels...
LBL A
RCL 00
x²
STO 01
RTN 
  ...with variable names and procedures names!
#label A au_carré
#reg 00 valeur
#reg 01 carré
LBL au_carré
RCL valeur
x²
STO carré
RTN 

Replace step numbers that you must calculate...
RCL 00
SBR 012
STO 01
R/S
x²
RTN 
  ...with label names calculated automatically!
RCL 00
SBR routine
STO 01
R/S
routine:
x²
RTN 

Replace tests, loops without visible structure...
RCL 00
x%t
RCL 01
x=t 017
RCL 00
+
DSZ 0 008
0
=
R/S 
  ...with structures as IF/ENDIF, or FOR/LOOP clearly defined!
RCL compteur
x%t
RCL reference
IF(x<>t)
FOR compteur
RCL compteur
+
LOOP
0 =
ENDIF
R/S 

Replace a dark key list...
RCL 00
+
RCL 01
=
STO 02
1 0 0 0
SUM 00
SUM 01 
  ...with visible logical units, with multiple affectation, sum or product:
#reg 2 somme
#reg 0 x
#reg 1 y
somme={ @x + @y = }
x,y+{ $1000 } 

Replace indirect addressing in non clearly defined zones...
4 STO 00
9 STO 05
RC* 00 x%t
RC* 05
INV x=t 022
OP 35
DSZ 00 006
R/S
... 
  ...with an array notation!
#ARRAY tab_1 1 4
#ARRAY tab_2 6 9
#reg 00 I
#reg 05 J
I={ TOP tab_1 }
J={ TOP tab_2 }
FOR I
@tab_1(I) x%t
@tab_2(J)
WHILE(x=t) difference
DEC J
WEND
R/S
difference: ... 

Replace codes and printing operations...
6413351713
OP 04
1 0 x² * Pi =
OP 06

  ...with text and clear orders!
"=area line>>
$10 x² * Pi =
MixLine ; this prints
; 314,1592654 =area 

The TI Compiler generates the complete listing for you to program your calculator...
000 76 LBL
001 10 E'
002 43 RCL
003 12 12
004 85 +
005 89 Pi
006 95 =
007 45 y^x
008 05 5
009 95 =
010 22 INV
011 59 Int
012 42 STO
013 12 12
... 
  ... but also the file loadable with the TI59.EXE emulator for a fast test and immediate debugging. (The default file name is TIEMUL.T59 and can be altered using #EMULATOR command). 
Link with TI59ce on Pocket PC
TI59ce is the second emulator supported byTI Compiler. It runs on Pocket PC and SmartPhone and is always updated by its author Alain Zanchetta.The previous emulator suffers from rare bugs that will never be corrected... Try this with TI59.EXE:
8888888888 2nd INT We expect 8888888888 But it returns 298954296.0 This bug doesn't exist in TI59ce that I recommend to you as its author is still active.
Under Windows XP, I use Microsoft's Device Emulator to simulate a Pocket PC and use TI59ce!For Device Emulator setup, please contact me.   TI Compiler outputs the file TIPPC.TI (default name, change it with #POCKETPC command) that TI59ce can load usingINV 2ND WRITE:

  The brand new emulator by Alain Zanchetta for Windows.
Based on his work for the PocketPC, here is his PC version. Numbers format has been totally reviewed to match the 13 digits decimal precision of the calculator.
This emulator comes with a debugger with register viewing and breakpoints!
Great work than you can download here.
TI Compiler outputs the file TIWIN.TI (default name, change it with #AZEMULATOR command) that the emulator can load usingINV 2ND WRITE 