Software Systems and Middleware

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[karlisberkolds]

What is Software ?

Programmable Hardware and the Emergence of Software Systems

The previous chapter introduced electronic hardware and the role of electronic components in implementing system functionality. However, the physical nature of hardware—and the inherent complexity of designing across mechanical, electrical, and logical domains—places fundamental limits on the speed and flexibility with which new system capabilities can be developed. To address these limitations, hardware platforms evolved to support programmability after fabrication. This programmability enables a separation between physical implementation and functional behavior, allowing systems to be adapted without redesigning the underlying hardware.

1. Configuration: In many modern systems, hardware components can be configured after silicon fabrication to support multiple operating modes or product variants. For example, parameters such as bus widths, cache sizes, or feature sets may be selected through configuration registers or firmware-controlled settings.
2. Hardware Function Realization: Certain hardware platforms support the post-silicon realization of hardware functionality through programmable logic structures. A canonical example is the Field Programmable Gate Array (FPGA), which enables designers to implement custom digital circuits after manufacturing. These devices are programmed using hardware description languages (HDLs), such as Verilog or VHDL, and have become foundational in embedded systems, prototyping, and specialized computing.
3. Programmable Processors: A broad class of stored-program computing engines based on the von Neumann architecture, including microprocessors and microcontrollers, falls into this category. Historically programmed in assembly language, these devices are now predominantly programmed using high-level languages such as C, along with higher-level abstractions in more complex systems.