ABAP Important TCODES

OSS1 SAP Online Service System

SM13 Update monitor. Will show update tasks status. Very useful to determine why an update failed.

S001 ABAP Development Workbench

SE01 Old Transport & Corrections screen

SE10 New Transport & Correction screen

SE09 Workbench Organizer

SE16 Data Browser: Initial Screen.

SE30 ABAP/4 Runtime Analysis

SE36 ABAP/4: Logical Databases

SE37 ABAP/4 Function Modules

SE38 ABAP Editor

SE39 Splitscreen Editor: Program Compare

SE41 Menu Painter

SE51 Screen Painter: Initial Screen.

SE71 SAPscript layout set

SE80 ABAP/4 Development Workbench Object Browser

SM12 Lock table entries (unlock locked tables)

SM21 View the system log, very useful when you get a short dump. Provides much
more info than short dump

SM35 View Batch Input Sessions
SQ00 ABAP/4 Query: Start Queries