https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Mobile_App_Development_2022W_Lecture_21 2026-04-06T01:53:55Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Mobile_App_Development_2022W_Lecture_21&diff=23974&oldid=prev 2022-04-01T17:46:02Z

<p>Created page with &quot;==Video== Video from the lecture given on April 1, 2022 is now available: * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec21-20220401.m4v video] * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec21-20220401.cc.vtt auto-generated captions] Video is also available through Brightspace (Resources-&gt;Zoom Meetings (Recordings, etc.)-&gt;Cloud Recordings tab). Note that here you&#039;ll also see chat messages. ==Notes=...&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on April 1, 2022 is now available:<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec21-20220401.m4v video]<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec21-20220401.cc.vtt auto-generated captions]<br /> Video is also available through Brightspace (Resources-&gt;Zoom Meetings (Recordings, etc.)-&gt;Cloud Recordings tab). Note that here you&#039;ll also see chat messages.<br /> <br /> ==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 21<br /> ----------<br /> <br /> Sending out emails today for randomized interview requests<br /> - will message on Teams when all emails have been sent<br /> <br /> Please try to sign up for slots on Monday or Tuesday<br /> - I&#039;ll add slots if needed<br /> <br /> You can sign up for interviews right now if you want to volunteer<br /> - on Teams, under the Annoucements channel, there&#039;s an &quot;Interviews&quot; tab which connects to a spreadsheet<br /> - if you want to ask about the grading of a question, please sign up for an interview<br /> <br /> <br /> Remember the final exam is cumulative<br /> - so it will have SwiftUI &amp; Android (so Swift &amp; Kotlin)<br /> - bit more Android than SwiftUI<br /> - no Storyboard except perhaps in extra credit<br /> - expect there to be questions connecting the two<br /> <br /> <br /> Operating systems<br /> -----------------<br /> Both Android and iOS are built on UNIX-like systems<br /> - Linux, MacOS/BSD UNIX<br /> <br /> First versions of UNIX were built in the 1970&#039;s<br /> - around 50 years ago!<br /> <br /> Still has same basic architecture<br /> <br /> Key terms:<br /> - kernel<br /> - process<br /> <br /> What is a process (in an OS context)?<br /> - running program<br /> <br /> A program on disk (program binary/executable) is loaded into a process in order for it to actually run<br /> - as part of this, it gets a certain amount of memory and some time to run on the CPU<br /> <br /> Processes are the abstraction that allows multiple programs to run on one computer at the same time<br /> - RAM is partitioned so each process can get some<br /> - the CPU is multiplexed<br /> - one program runs for 1/100 of a second, then another runs for 1/100 of a second, and so on (they take turns)<br /> - nobody gets to run for more than their alloted time<br /> <br /> For a process to take up multiple cores, it must be multithreaded<br /> - each thread runs on one core<br /> - all threads of a process together share memory, together they make a process<br /> <br /> The OS kernel is the program that facilitates sharing between running programs<br /> - it implements the process abstraction<br /> - it thus is &quot;in charge&quot;, can create and destroy processes at will<br /> (and can create and destroy any data, communicate with anything)<br /> <br /> How can the kernel be &quot;in charge&quot;?<br /> - well, it ran first! (It was started first, it then lauchches all the processes)<br /> - it runs in a special CPU mode, supervisor mode<br /> - regular processes run in user mode, and so have more limited access<br /> <br /> This is why when regular programs crash, they don&#039;t take the whole system down<br /> - but if your GPU driver crashes, it can kill your whole system, because<br /> it runs in the kernel<br /> <br /> Mobile operating systems are mostly the same as desktop ones (and server ones)<br /> - same basic kernels &amp; processes<br /> <br /> But mobile ones have some extra restrictions<br /> - processes tend to be more sandboxed (isolated from other processes)<br /> - especially on iOS<br /> - extensive &quot;permission&quot; infrastructure for gaining access to special resources<br /> - location, camera, address book<br /> &lt;/pre&gt;</div>

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