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I have been learning about the basics of electronics, and reverse engineering hardware using UART connected to my computer. I find it interesting how I can access the busybox which is Linux and then make it perform cool and interesting new features.

My question is how consumer devices used to work before they all got shipped with Linux? I understand there may have been other operating systems for hardware, but I assume that there was a point where there was no operating system to control it, if we go far enough into the past?

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    \$\begingroup\$ Discrete circuits > logic ics > basic microcontrollers > computers. \$\endgroup\$ – Passerby Jul 26 at 0:21
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    \$\begingroup\$ The farther back you go, the simpler processors were. The simpler a processor is, the more feasible it is to just hard code everything. The real purpose of an operating system is to allow the programmer to ignore a lot of hardware details when coding and allow that code to run on multiple platforms. \$\endgroup\$ – DKNguyen Jul 26 at 0:39
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    \$\begingroup\$ There were a lot of embedded operating systems around 20 years ago that became less common overtime as things like Linux became more capable and more widely supported. \$\endgroup\$ – user1850479 Jul 26 at 0:42
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    \$\begingroup\$ There are still lots of electronics without Linux. There are many things that use dedicated microcontrollers that don't use any operating system,and lots of thing that don't use any form of "computer". \$\endgroup\$ – Peter Bennett Jul 26 at 2:16
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    \$\begingroup\$ Plenty of things still don't have a full operating system; typically it starts to make sense about where IP networking or large data buffers are involved. However, this question fails the stack exchange requirement of specifity - this is something that belongs on a discussion site, but stack exchange is very purposefully not for discussion, but only for things which can be specifically and definitively answered. \$\endgroup\$ – Chris Stratton Jul 26 at 2:22
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Before embedded microcontroller systems there were application specific ICs like SANYO LM8560 (alarm clock ic) and lumped logic like that used in the ROLAND CR-78 (drum machine)

Once microcontrollers became economial they were embedded with a first a non-hosted application (the microcotntroller boots straight into the application code)

Example pc keyboards and keyboard interface ics.

And later (once there was suffuicient complexitity) with operating syustems hosting the applications software.

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  • \$\begingroup\$ Before microcontrollers had operating systems, what was the difference between a microcontroller and an integrated circuit (IC)? \$\endgroup\$ – securityauditor Jul 26 at 16:11
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    \$\begingroup\$ @securityauditor: "Integrated circuit" is a very general term, covering anything from a couple of transistors in a common package up to the largest microprocessor. The earliest digital ICs may have had one or two simple gates in the packege. Early analog ICs were probably op-amps. \$\endgroup\$ – Peter Bennett Jul 26 at 16:27
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    \$\begingroup\$ microcontrollers are general purpose computers (ie Turing-complete) that execute code this is a subset of IC \$\endgroup\$ – Jasen Jul 26 at 21:21
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how (did) consumer devices used to work before they all got shipped with Linux (?)

Linux was released in 1991 for x86 devices which had UARTs but now is ported to every CPU architecture from A to X which is almost everything under the Sun which followed the path of IBM's development of Unix which started in 1969. The Unix and alike history is shown below gives you an idea of the systems developed for military and business that later went into consumer products.

enter image description here Eraserhead1, Infinity0, Sav_vas / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

This is more of an OS genealogy of systems answer, some of which went into consumer items.

The consumer products, which I helped develop in the early 80's used a proprietary real-time OS with synchronous transmitters and some with UART's for exchanging data with the home computers on a CATV network, using an unused TV line (VITS) with proprietary data rates of 4Mbps used for streaming game files in '83 era to the Commodores, TRS-80, Apple ][ etc. It was demonstrated at a Vegas Cable TV tradeshow but failed to get any orders. (which is why no one has heard of it around then)

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The first electronic items for consumers, with STATE maintained by digital logic, were 4_function calculators about 1975.

Before that, RCA TVs used ultrasonic remote_controls to rotate the channel_selection drum, with the mechanial drum position being the "State".

In a non_consumer system, there was the SAGE Strategic Air Ground Environment system, using numerous dual_redundant computer systems, all networked with phone lines between each other (in days before Internet, or even lasers to drive fiberoptic cables) and with phone lines to/from radar sites (such as BMEWS up in Greenland on land and on long-legged shallow-water platforms off Nantucket) to report incoming USSR bombers to the SAGE system, that then communicated to US air bases for vectoring USAF fighters to intercept the incoming bombers.

SAGE was designed and up and running in the 1950s, and continued operating until the 1980s. SAGE used custom-designed computers, that were ........ vacuum tube logic and spinning drums/magnetic-READ-HEAD state preservation.

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