Abstract: A converter and method (10) for converting an assembly language computer program (12) into a high-level language computer program (20, 22) includes the steps of reading and storing the assembler listing (18) into an array in memory (102), logically tracing said assembler listing (112), determining which lines are reachable logically, and marking reachable and unreachable lines accordingly, and further determining an instruction type for each reachable line and identifying each line by type accordingly (114). A data table having a hierarchy of data elements in said assembler listing is built (118), a data division from said data table is generated (134), and an hierarchy of sections of code caused by perform instructions in said assembler listing are identified and labeled (122, 124). The assembler listing is converted into a source program in said high-level language and unloaded as the high-level language source program from memory.