At the present time, with the high reliability and performance of computer hardware, computer systems applied in any field must be judged more by the quality of the software provided. Thus it is highly relevant in an investigation of the use of computers in a field such as animal production, to concentrate on aspects of the software.

Software provides the computer with the ability to obey instructions and to do as the user wishes. However, before arriving at these ‘machine instructions’ a number of steps have to be covered. First, it is essential to design the software — that is, to establish the requirements to be achieved on the computer. This design stage is followed by the implementation phase, in which the requirements as stated in English are transformed into such instructions as the machine can read and obey. The final phase is testing, in which it must be determined whether the requirements have been met, and to modify the design and iterate until the performance is satisfactory.

Software in general can be divided into three classes — systems, utility and applications software. The systems software drives the machine and its associated peripherals such as a VDU and printer. The systems software also includes a file system for organization of the data on the relevant storage media (floppy disks, cartridges, magnetic tape). Also considered part of the systems software are the assembler, interpreters and compilers for high level languages such as BASIC and FORTRAN and for programming aids such as DEBUGGERS. Systems software is normally supplied with the computer and needs to be evaluated along with the hardware by any prospective purchaser of a computer system.