The original real-time system, hardware, is still the go-to for extremely tight tolerance and/or fast timing requirements. It can be implemented with discrete digital logic, analog components, programmable logic, or an application-specific integrated component (ASIC). Programmable logic devices (PLDs), complex programmable logic devices (CPLDs), and field-programmable gate arrays (FPGAs) are the various members of the programmable logic device portion of this solution. Hardware-based real-time systems can cover anything from analog filters, closed loop control, and simple state machines to complex video codecs. When implemented with power saving in mind, ASICs can be made to consume less power than an MCU-based solution. In general, hardware has the advantage of performing operations in parallel and instantly (this is, of course, an over-simplification), as opposed to a single-core MCU, which only gives the illusion of parallel processing.

The downsides for real-time hardware development generally include the following:

• The inflexibility of non-programmable devices.
• The expertise required is generally less commonly available than software/firmware developers.
• The cost of full-featured programmable devices (for example, large FPGAs).
• The high cost of developing a custom ASIC.