Program conversion - One successful paradigm

The continuing rapid development of computer hardware over the years has been both a blessing to the user who sees his computing power increase and cost decrease over time, and a disappointment to those who have found that the cost of converting existing software outweighs the advantages of the new machines. For any proposed change of hardware, there are at least three options whose cost the user must carefully weigh-( 1) the option of remaining with older hardware, (2) the option of completely redesigning/rewriting existent software and (3) the option of converting those portions of the existing software which are portable and rewriting the rest. At BBN we have recently carried out the transfer of a large body of programs from one hardware environment to another. In the process of this task, we have developed an analytical approach to the problem of conversion of programs written in a partially independent higher-level language. Our technique consists of several distinct phases: