The first truely mechanical calculating machines were devised in the XVII century by a number of computer enthusiasts. Complex systems of levers, gears, wheels and dials were used to perform complex calculations for a wider range of applications, including computer aided design, tax reporting and retirement planning.

While the number of enthusiasts and visionaries grew, the hardware industry was unable to keep up. The fine art of designing and manufacturing the delicate wheels and mechanisms needed by these machines had not been perfected enough.

This resulted in manufacturing flaws which in turn led to numerous bugs. And while programming these devices was no easy task, debugging flawed code and fixing corrupted data and results was even more complicated. All of these added to the already demanding task of operating the machine - some models required operators with significant physical strength for turning the master lever (see photo). The lack of software and hardware standardization compounded problems faced by users. This situation limited the spread and use of these early computational devices. Lack of standardization and bugs basically killed the use of the devices in fields such as tax and accounting reporting. While lacking commercial success, the few models that were manufactured ended up as means of entertainment for children of wealthier families.

As it sometimes happens, progress was driven by a different type of demand: word about the new devices spread among children of wealthier families and owning such mechanical wonders became a must for trendy youngsters in the XVII century. This increased demand was beneficial for the hardware and software technologies of the day, and led to the development of improved models.