Computer Structure & Introduction to Digital Computer: All in One Guide Made Easy

A Digital computer can be considered as a digital system that performs various computational tasks.
The first electronic digital computer was developed in the late 1940s and was used primarily for numerical computations.

And also;
In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implementation of computer systems. Some definitions of architecture define it as describing the capabilities and programming model of a computer but not a particular implementation. In other definitions computer architecture involves instruction set architecture design, microarchitecture design, logic design, and implementation.