Justifications and trade-offs of historical hardware and software designs, and their possible alternatives.
You can use this tag to ask why a historical item of hardware or software was designed a certain way and how else it could have been designed: what were the design considerations, which use cases were targeted and what trade-offs constrained the design.
Keep in mind that design choices that may seem obvious now need not have been so at the time the choices were made. Be aware of hindsight bias.
Additionally, objective, explicit evidence of design justifications is, unfortunately, often enough scant to nonexistent. This means that answers will often necessarily be speculative to one extent or another. Even if you are willing to accept this, you should encourage answerers to provide evidence for their claims, and to appropriately mark the extent to which their answers are speculative or rely on incomplete evidence.