Data terminal with capability of checking memory storage capacity as well as program execution parameters

A data input/output terminal includes a central processing unit, a random access memory (RAM), a display unit, and various data entry devices for inputting and outputting data to a host processor. The terminal includes the capability of setting program execution parameters which are necessary for the proper execution of various programs, and stores check sum codes of the parameters into an area of the RAM. Upon initial turn-on of power, the terminal determines the correct storage of the parameters in the RAM by re-calculating the check sum codes and comparing the re-calculated codes with the codes previously stored in the memory. The terminal also determines whether the RAM contains additional data storage capacity and indicates whether the RAM is capable of storing additional data or whether the RAM is full.