Tomasz Wojtowicz
Schedae Informaticae, Volume 24, 2015, pp. 179 - 195
https://doi.org/10.4467/20838476SI.16.016.4357Transistor level simulation of the CPU, while very accurate, brings also the performance challenge. MOS6502 CPU simulation algorithm is analysed with several optimisation techniques proposed. Application of these techniques improved the transistor level simulation speed by a factor of 3–4, bringing it to the levels on par with fastest RTL-level simulations so far.
Tomasz Wojtowicz
Schedae Informaticae, Volume 24, 2015, pp. 197 - 210
https://doi.org/10.4467/20838476SI.16.017.4358Deep understanding of microprocessor architecture, its internal structure and mechanics of its work is essential for engineers in the fields like computer science, integrated circuit design or embedded systems (including microcontrollers). Usually the CPU architecture is presented at the level of ISA, functional decomposition of the chip and data flows. In this paper we propose more tangible, interactive and effective approach to present the CPU microarchitecture. Based on the recent advancements in simulation of MOS6502, one of the most successful microprocessor of all times, that started the personal computing revolution, we present the CPU visualisation framework. The framework supports showing CPU internals at various levels (from single transistor, through logic gates, ending with registers, operation decoders and ALU). It allows for execution of real code and detailed analysis of fetch–decode–execute cycle, measurement of cycles per operation or measurement of the CPU activity factor. The analysis means provided by this framework will also enable us to propose the transistor level simulation speed improvements to the model in the future.