A more and more important area — even if not all cases contain a computer (i.e. laptop / desktop) today, “all” cases have a mobile phone.

With the advent of the “internet of things” (i.e. “the internet of crappy insecure things”) except to find “gadgets” in most / all / majority of cases in 5-10 years.

Embedded systems are like a normal computer but:

• often have stricter constraints on memory, storage, processing power, lower power consumption
• Often a realtime system (soft), with limited keyboard (buttons), screen (status lights), sensors rather
• Many smaller systems are SoCs (System-on-ac-cip) with CPU, memory (RAM/Flash), peripheriphals, etc.. al on one die.

System on a chip

C.f. Arduino based on e.g. Atmel AVR ATMega328.

The AVR architecture was conceived by two students at the Norwegian Institute of Technology (NTH), Alf-Egil Bogen and Vegard Wollan

The original AVR MCU was developed at a local ASIC house in Trondheim, Norway, called Nordic VLSI at the time, now Nordic Semiconductor, where Bogen and Wollan were working as students. (Wikipedia)

Says to retain data for over 20 yeras at 85°C or 100 years at 25°C with probability of loss less than 1 PPM.

Power 328P 0.2mA when active, 0.75uA when power-save.

Other (more) popular architectures are e.g.

• 8051 — Old as the hills, dirt cheap, everywhere (like cockroaches)

• ARM —- More modern, 32-bit RISC, in every phone in this room

  Architecture reference manuals are a mess.. many different variants

Example: every hard drive today typically contains an 8051 and two ARM cores (+ memory etc…). It’s a pretty decent computer in its own right - an 80s supercomputer in fact.

Mobile phones

There are a couple of popular OSes for mobile phones:

• Various proprietary OSes for “cheap” non-smartphones — ISA for Nokia phones etc..

• Android (Google) — smart phones from many different manufactures and tablets etc…

  ARM, Linux kernel, but not Linux userland