Speed path
In the production of main processors , these are classified in the final inspection with regard to their cycle stability, with physical properties such as signal levels at different clock frequencies being checked using a test program developed individually for each processor type . Here, especially in term of critical paths on the CPU The respected. If a signal above a certain signal path does not run fast enough to meet the logical requirements of the CPU design, it is called a speed path English or speed Path . Put simply, this means that if the clock frequency were increased further, the signal would no longer arrive in time where it is needed. Such speed paths limit the clock frequency of all complex logic modules , just like a CPU is. Smaller production structures reduce the signal propagation time between the transmitter and receiver, which means that higher clock rates are possible without malfunction. However, it can happen that other interference effects, such as leakage currents or crosstalk between adjacent lines, occur as a result. Thus, no general relationship between structure size and maximum cycle can be formulated.
If such a speed path remains undetected, it can have fatal consequences: for example, various revisions of the AMD K6 showed an error in the MMX unit caused by an overlooked speed path due to variations in the manufacturing quality, which corrupts the transferred data and, for example, when unpacking JPEG images could lead to data garbage. In addition to production, the design of the CPU also plays a decisive role in the occurrence of speed paths. The company Intel had similar problems. In 2001, the recently introduced Pentium III with a clock frequency of 1.13 GHz had to be recalled because Intel had overlooked a speed path .