This is my summary of the inventions I learned about in lessons one hundred sixty-one through one hundred sixty-four.

In lesson one hundred sixty-one, I studied the invention of Unix. Before Unix, computers were hard to work with and program. The first computer had about eighteen thousand vacuum tubes and was very time consuming to program. You had to flip tons of switches to load a program, as opposed to now, when you can simply double click an icon. After that, computers functioned using transistors, but they were still pretty slow, and the operating system they used was called Multics. Multics was good, but not good enough, and programmers were hired to improve it.

Two of these improvers were Ken Thompson and Dennis Ritchie. Thompson programmed his own video game that ran on Multics, so when Bell Labs pulled out of Multics, he wanted to rewrite it so he could keep playing. Ritchie helped Thompson with this, and together they wrote a new operating system called Unix. It was similar to Multics, but much simpler. Unix was released in 1969, and made programming easier.

Next, in lesson one hundred sixty-two, I learned about the invention of the microprocessor. Before the microprocessor, computers were huge and could only do one task. If you wanted it to do something else, you needed to rewire the processor. The microprocessor changed this, and it was invented in 1971 by when Busicom wanted a better chip for their calculators. A microprocessor is an integrated circuit that contains the CPU (Central Processing Unit) and memory in a very small space. Before, processors were made for specific computers, but the microprocessor was generic and could be used in various types of computers.

In lesson one hundred sixty-three, I learned about this invention of the video game console. The video game console was invented by Ralph Baer in 1972. Baer was interested in electronics, and this led him to create something that could be hooked up to a television to display videos.

Last of all, lesson one hundred sixty-four was about the invention of the VHS and the VCR. Before either of them, there was no way to record television shows. They were on once, and that was it. The VCR (Video Cassette Recorder) was invented in 1977, and it provided a way to do just that. However, the VCR was mostly used for commercial purposes, and the VHS (Video Home System) was then developed for home use. Both the VCR and the VHS allowed people to record their favorite shows and watch them whenever they wanted.