One of the most important invention in the design of digital circuits is that of the general- purpose "stored program" computer or device. Computers are a particular type of digital circuits that are used as general purpose: the same actual circuit can operate any transformation between its outputs and its inputs. Which particular transformation it operates is governed by a program, which is some parts of physical switches, or information given on an external physical memory, such as tapes or a cards, or information saved in some sort of internal physical memory.
Exactly what operations a computer can do relays on the amount of memory it has; and also on the time you want to wait. So, although a general-purpose computer may do anything a special-purpose digital electronics circuit may do, in the information processing sense, the computer can be slower or use more power. However, operating general-purpose computers can save effort and time. It is much simpler and easier to debug and change and manufacture software than hardware. The abstractions and modularity that software PCAP systems provides us are even more powerful than those given from the digital circuit abstraction.
Again, we may see how abstraction divide use from information; we don't require to know how the circuits inside a computer machine are designed, we just have to know the methods by which we may use them and the constraints under which they operate.