Shortcomings of array structures of the modern pipeline computer systems are analyzed, including information managing directors of system of critical application. Feasibility of abbreviation of array structures justifies need of development of resources – models, methods and means – for on-line testing of bitwise pipeline system. On the basis of resource approach the models determining further enhancement of methods and means of on-line testing of bitwise pipelines including models of data and a result, an operation and data access are offered and develop. The data model which gained development from integer numbers to approximate ones in floating point formats distinguishes most and least significant bits in which faults of digital circuits cause respectively essential and inessential errors in relation to trustworthiness of result. In order to detect essential errors, the models are developed for methods checking the calculated results by inequalities. The model of operation determines accessibility of result to its assessment by methods and means of on-line testing. Result models, serving for it by the lower and upper boundaries, are defined and evaluated, following from restrictions which are superimposed on operands by the used data formats. Models of data access formalize procedures of a choice of operands and results for verification of check ratios in bitwise pipeline systems. Models are considered for key operation of approximate calculations – multiplication, and also for inverse operation of division.