1. A PROM writer, comprising: (a) first memory means for storing a system program and a first writing algorithm; (b) second memory means for storing data to be written into a PROM; (c) CPU means operatively coupled to each of the first and second memory means and the PROM for executing the system program, the system program including a command which causes the CPU means to write the data stored in the second memory means into the PROM according to the first writing algorithm; (d) third memory means coupled to the CPU means for storing a second writing algorithm; and (e) interface means coupled to the CPU means for supplying the second writing algorithm to the CPU means, the system program causing the CPU means to store the second writing algorithm in the third memory means; wherein the system program includes a command which causes the CPU means to write the data stored in the second memory means into the PROM according to the second writing algorithm.