| The computer systems used in the crisis fields such as spaceflight, avigation and national defence must be developed by ourselves for the sake of nations safety and reliability. Though most of them are highly dependable fault-tolerant computer systems, as an important method of dependability testing and capability assessing, fault injection plays an important role in the development of fault-tolerant computer systems.The advantages and disadvantages of some popular technologies of fault injection are compared in this paper. As for the project of design fault injection to 80486 chip, the method of embedded fault injection is embodied and accomplished in the work of 486-fault-tolerant testing machine, the first embedded fault injector of our county. This technique inserts a socket between the target hardware and its circuit board. The inserted socket can inject faults into the target system by forcing the analog signals which represent desired logic values onto the pins of target hardware. Key techniques are embodied in the design, including synchro-control, direction-control, and delay-control.486-fault-tolerant testing machine can inject up to 62 injection points simultaneously, including all address and data signals of 486 chip. 486-fault-tolerant testing machine can inject stuck -0, stuck-1 and bit-flip faults, moreover it can also control the length of fault existence and the frequency through setting time types of faults, including permanent, transient and intermittent types. Based on the random and delay triggering mechanism, a new triggering mechanism, target triggering is proposed. The results of injection are collected and saved automatically. The dependability and capability of target fault tolerance system can be drawn from these data. |
