https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Operating_Systems_2020W_Lecture_4 2026-06-02T22:28:27Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2020W_Lecture_4&diff=22569&oldid=prev 2020-03-20T02:30:26Z

<p>Created page with &quot;==Video== Video from the lecture given on January 17, 2020 [https://homeostasis.scs.carleton.ca/~soma/os-2020w/lectures/comp3000-2020w-lec04-20200117.m4v is now available]....&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on January 17, 2020 [https://homeostasis.scs.carleton.ca/~soma/os-2020w/lectures/comp3000-2020w-lec04-20200117.m4v is now available].<br /> <br /> ==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 4<br /> ---------<br /> <br /> What is a assembly-language view of a computer?<br /> <br /> * hardware registers<br /> - general purpose registers<br /> - special purpose registers<br /> - status/flag registers<br /> - access and manipulate by specifying register directly or<br /> registers change behavior indirectly<br /> <br /> * memory (RAM)<br /> - each memory location has a unique address<br /> - get value or change value by specifying address<br /> <br /> * (maybe) I/O ports<br /> - access to devices<br /> <br /> <br /> This assembly-language view is implemented in UNIX processes<br /> <br /> registers<br /> - &quot;variables&quot; that can be manipulated by instructions<br /> - size varies, but 64-bit computers generally have 64-bit registers<br /> <br /> modern computers mostly follow a load-store architecture<br /> - load value(s) into registers from RAM<br /> - manipulate values in registers<br /> - save registers to RAM<br /> <br /> (cache (L1, L2, L3)<br /> - faster memory to make register&lt;-&gt;memory operations faster<br /> - cache not visible to programs)<br /> <br /> To add two numbers together in two variables x and y and store in z<br /> - load x into a register<br /> - load y into another register<br /> - add registers together, store result in one of them<br /> - save result register to z<br /> <br /> <br /> Modern CPUs have very few registers<br /> - at most 64 registers<br /> <br /> Hennessey &amp; Patterson, Computer Architecture, a Quantitative Approach<br /> - read this to learn more about computer architecture and the performance<br /> tradeoffs<br /> &lt;/pre&gt;</div>

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