{"id":1003,"date":"2016-09-18T13:45:08","date_gmt":"2016-09-18T08:15:08","guid":{"rendered":"http:\/\/abhinav.spsdarj.org\/?p=1003"},"modified":"2016-11-22T03:12:53","modified_gmt":"2016-11-21T21:42:53","slug":"whats-with-32-bit-systems-supporting-max-4gb-of-ram","status":"publish","type":"post","link":"https:\/\/abhinavkr.com\/musings\/2016\/09\/whats-with-32-bit-systems-supporting-max-4gb-of-ram\/","title":{"rendered":"What’s with 32 bit systems supporting max 4GB of RAM?"},"content":{"rendered":"

So you know that RAMs contain storage space. Common sense. Every byte<\/strong> of memory on RAM requires to have an address allocated to it.\u00a0A 32-bit machine uses 32 bits long address to designate each byte of memory. And a memory that does not have an address allocated can not be seen by the machine<\/em>.<\/p>\n

Now let’s understand how these addresses work.<\/p>\n

Each bit has a value of 0 or 1. If you have 1 bit long address, you have two possible addresses: 0 or 1. A two-bit system has four possible address: 00 =0, 01=1, 10=2, 11=3. 2^2=4. Three bits have 8 possible addresses: 000=0, 001=1, 010=2, 011=3, 100=4, 101=5, 110=6, and 111=7.<\/p>\n

Each bit doubles the potential address space, which is why 2^n tells you how many addresses you use for a given number of bits. 2^1 = 2, 2^2 = 2*2 = 4, 2^3 = 2*2*2 = 8, etc.\u00a0By the time you get to 32 bits, you\u00a0have allocated address to 2^32 =\u00a04294967296 bytes of RAM space which is equal to 4GB<\/code>.<\/p>\n

(((2^32bytes\/2^10)KB)\/2^10)MB)\/2^10)GB = 2^2GB<\/em><\/pre>\n
\n
Okay, so if the processor, and the operating system designed for that processor, can only handle 4GB, why can’t your PC (if it’s 32-bit) see that much practically?<\/p>\n
Because not all of those addresses are available for RAM. There are other pieces of hardware inside your computer that need addresses, such as the PCI bus and the USB host adapter, Graphics card, etc.<\/p>\n
\n
Whenever you store something in the memory, you need to save the address to be able to read or manipulate it. Usually, the CPU uses only one register (32 bit in size) to store this address. Since there are only 2^32<\/code> different addresses, anything exceeding the 4GB<\/code> mark remains unused.<\/p>\n
However, there are techniques like Physical Address Extension (PAE) that allow a 32-bit OS to address more than 4GB<\/code> of RAM.<\/p>\n
\n
Source of some info<\/a>, More Source<\/a><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
So you know that RAMs contain storage space. Common sense. Every byte of memory on RAM requires to have an address allocated to it.\u00a0A 32-bit machine uses 32 bits long address to designate each byte of memory. And a memory that does not have an address allocated can not be seen by the machine. Now…<\/p>\n","protected":false},"author":1,"featured_media":1007,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[189],"tags":[215,216,217,214],"class_list":["post-1003","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tech","tag-32-bit","tag-64-bit","tag-memory","tag-ram"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/abhinavkr.com\/musings\/wp-content\/uploads\/2016\/09\/Memory_module_DDRAM_20-03-2006.jpg?fit=2304%2C1728&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p4KGvB-gb","jetpack-related-posts":[{"id":849,"url":"https:\/\/abhinavkr.com\/musings\/2015\/10\/does-the-size-of-ram-affect-speed-of-computer-if-yes-how\/","url_meta":{"origin":1003,"position":0},"title":"Does the size of RAM affect speed of computer? If yes, how?","author":"Abhinav","date":"October 21, 2015","format":false,"excerpt":"Answer by Prasannjeet Singh:Well, in some cases it does and in some, it does NOT affect the speed of the computer.Let me explain this metaphorically: (I think Indian readers will understand this better!)There is a street food in India called as Pani-Puri (also Golgappa).\u200b\u200bLittle about this street food (Skip this\u2026","rel":"","context":"In "Quora Post"","block_context":{"text":"Quora Post","link":"https:\/\/abhinavkr.com\/musings\/category\/quora-post\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1419,"url":"https:\/\/abhinavkr.com\/musings\/2017\/12\/how-to-redirect-base-url-addresses-to-another-base-url\/","url_meta":{"origin":1003,"position":1},"title":"How to redirect base url addresses to another base URL","author":"Abhinav","date":"December 11, 2017","format":false,"excerpt":"Say you have\u00a0http:\/\/abhinav.spsdarj.org\/2017\/12\/how-to-redirect-base-url-addresses-to-another-base-url\/ as a url on your old website (abhinav.spsdarj.org) and now you want the link to redirect to new website. Say\u00a0abhinav.ga\u00a0but the url following abhinav.ga should stay the same and when typing the old url, should magically redirect with rest of the link intact to the new website.\u2026","rel":"","context":"In "Tech"","block_context":{"text":"Tech","link":"https:\/\/abhinavkr.com\/musings\/category\/knowledge\/tech\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1298,"url":"https:\/\/abhinavkr.com\/musings\/2017\/02\/do-you-have-a-simple-childhood-memory-that-you-could-never-forget\/","url_meta":{"origin":1003,"position":2},"title":"Do you have a simple childhood memory that you could never forget?","author":"Abhinav","date":"February 16, 2017","format":false,"excerpt":"Do you have a simple childhood memory that you could never forget? by Corey Herbert Answer by Corey Herbert: Yes. It\u2019s 1986, I\u2019m 9 years old and I come downstairs to get ready for school. My dad is reading the paper and he says, \u201cHey Corey, what do you know\u2026","rel":"","context":"In "Life stuff"","block_context":{"text":"Life stuff","link":"https:\/\/abhinavkr.com\/musings\/category\/life-stuff\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":677,"url":"https:\/\/abhinavkr.com\/musings\/2015\/02\/gettysburg-address\/","url_meta":{"origin":1003,"position":3},"title":"Gettysburg Address- Abraham Lincoln","author":"Abhinav","date":"February 8, 2015","format":false,"excerpt":"Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal. 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