Lecture 3/12: Bits, Bytes and Words

Prof. Harry Porter
Portland State University
cs.pdx.edu/~harry

[@smoothbeak]

You're a computer wizard Harry!

[@Nobodyyoucarabout]

i read harry potter as well the first time hahaha

[@Kor1134]

Octal is used in Linux to set file and directory permissions: 1 = x, 2 = w, 4 = r; 6 = 4+2 = rw; 7 = 4+2+1 = rwx.

[@ideaparkcc]

A master does not make you lost by complexities, but make you more clear by simplicities. Harry is absolutely a real master.

[@Kor1134]

I've never heard of a half-word, I see 16-bit integers in Linux called characters, and in Windows called words. Windows still denotes 32-bit integers as dwords, as evident in the registry. C++ and C# represent dwords as 32-bit integers

Really liked this one. I try using LEGO to explain Bits and Bytes, let me know what you think. I do like your "white-boarding"method of explaining.

[@ranjithvengala2412]

Danielle Thé me too like this kind of explanation...

[@dominicgaraycochea704]

I like the flow of the lecture.. Subscribed!

[@arielspalter7425]

Super clear. Thanks for the video.

[@mithunkumarv2321]

1 word = 8/16/32/64/... bits depending on memory word size. But here you have mentioned that 1 word = 32bits Is it applicable only for 32 bit machine?

[@saratmondal2000]

Yes, in ladder programming 1 word =16 bit and 1 double word=32 bit..

[@edwardgoldentooth4491]

@@saratmondal2000 loada nonsense. Obfuscating the issue

[@KabelkowyJoe]

This tutorial Is applicable to virtual world of non existing machines it means - WRONG> In x86 terminology/documentation either 32bit and 64, a "word" is 16 bits PERIOD because x86 evolved out of 16-bit 8086. Same on ARM cause it's both 32 and 64 bit also contain 16 bit Thumb mode. In WIndows programing DWORD = 32 bit, QWORD is 64 this tutorial is worthless. I quote stackoverflow now "Changing the meaning of the term as extensions were added would have just been confusing, because Intel still had to document 16-bit mode and everything, and instruction mnemonics like cwd (sign-extend word to dword) bake the terminology into the ISA.x86 word = 2 bytes x86 dword = 4 bytes (double word) x86 qword = 8 bytes (quad word) x86 double-quad or xmmword = 16 bytes, e.g. movdqa xmm0, [rdi]. Also in the cqo mnemonic, oct-word. (Sign-extend RAX into RDX:RAX, e.g. before idiv) And then we have fun instruction like punpcklqdq: shuffle together two qwords into a dqword, or pclmulqdq for carry-less multiplication of qwords, producing a dq full result." To avoid confusion, SIMD mnemonics tend to be AVX vextracti128 or AVX512 (with optional per-element masking) vextractf64x4 to extract the high 256 bits of a ZMM register." - therefore in REAL life WORD is 16 nobody else uses other definition.

[@amansouravsrivastava2405]

A real Harry Porter!!

[@treimar]

Video was very helpful eventho in the PLC world a word is 16 bits.

[@vvvv-pb5qk]

No spells??? How are we going to defend against the Dark Lord?!!?!?

[@kqvanity]

14:43 can be used as a type modifier with other specific data types to add a modification to it

[@guliyevshahriyar]

Thx

[@dwl.sinamurye208]

How many bytes in the following sentence " Is you, who broke my phone" henry said to betty

[@anelectrician]

A Nibble is 4 bits

[@infotothecitizens2117]

very interesting

[@jmpbus5086]

Thank you, this is a very helpful video.

[@JaffarHussain]

Please solve this questions 1- What is the computer system components? 2- Please give a few examples of Application programs, Hardware Computer System Components. 3- Are following attributes true for I/O Structure? A. Each device controller has a controller. B. Each local buffer is in charge of a particular device type. C. CPU moves data from/to main memory to/from local buffers D. Each device controller is in charge of a particular device type 4- What is default unit of computer storage size that contain one of two values, 0 and 1? A. One bit B. One word C. One byte D. Gigabyte 5- What does the Caching exactly do? 6- List the Advantages of Multiprocessors systems? 7- What is Bootstrap program designed for? A. bootstrap program is loaded at ROM or reboot B. Initializes all firmwareof system C. Loads operating system kernel and starts execution 8- What is the responsibility of Secondary storage, Symmetric Multiprocessing, Asymmetric clustering, Timesharing? 9- Please give the parallel systems types for Computer-System Architecture? 10- What does the cluster system exactly do? 11- What is Operating System Definition? 12- What are the (CPU scheduling, swapping, Virtual memory, job scheduling) are used for? 13- What is the kernel? 14- How a Modern Computer Works draw and explain?

[@infinitesimotel]

Why don't you, try to solve them buddy?

[@TheTechnicalman]

*Word* consists of 4 letters and 4 bytes ;)

[@kefrensmegademo]

I think "longer int" data type can be shortcut for "long long int" in C . lol.

[@edwardgoldentooth4491]

do you mean "integer", this bloke is a nutter

[@ArsArcanum]

can you do your lectures in snake tongue... plz Harry?

[@edwardgoldentooth4491]

he is lol (numpty)

[@PravinJanjal92]

So great!

[@drwblkfact7286]

Thank you !!!

[@sakirdag2976]

thank you

[@vpetevotov]

Thank you!

[@rashidmhr]

"Harry Porter and the chamber of bytes"

[@Thank_Me_Later]

DWORD IS 32BIT ?

[@mr.latief2728]

Sorry correction, 1 Word = 2 byte = 16 bite, double word = 4 byte = 32 bite, Thanks

[@warlockzone9596]

Good video! ... Octal is used in networking - IP addresses - IPv4 xxx xxx xxx xxx

[@Kor1134]

Those are byte-sized decimals, 192 and 168 are not valid octals since octal can only count from 0 to 7 in one digit. You will never see an 8 or 9 in an octal number. You're thinking of octets, not octals.

[@edwardgoldentooth4491]

1024 bits to a kilo byte. why confuse? loada bollix lol

[@yank3656]

thanks for sharing hhp3

[@jamespottex5197]

Good video very helpful for poor class students

[@thepeach12345]

They want to contact alien life in outer space so they use numbers but did anyone tell the aliens that hey we decided to start from the right to left and in a specific 4 number order this means counting up and not down? What if the aliens had 1 byte deciding it would be I dont know lets say 9 characters like out social security numbers in the US? How would they know what they are looking at? lol.

[@muhammadshaheer1648]

How a 32bit Architecture can store (longlong or double) datatype as size of long long or double is 8byte=64bit? I am confused. Can anyone please clear my doubt.

[@codedbyjordan]

32bit means that 2^32 memory addresses are able to be used by the CPU. each memory address stores 1 byte of data in it.

[@RATANAGARWALITINFORMER]

thx

[@rajadurai1483]

super

[@Killputin777]

mukay?

[@KabelkowyJoe]

WORD 32, WAIT WHAT! WHAT?! In what realm!? In Windows and Linux programing world WORD was always 16 bits, Double WORD is 2x 16 bits 32bits, Quad is 64 bits, Double QWORD is 128. This tutorial Is not applicable to REALITY it means - WRONG. Except for bits to octal calculation. In x86 terminology/documentation, a "word" is 16 bits PERIOD because x86 evolved out of 16-bit 8086. In WIndows programing DWORD = 32 bit, even on 64 bit architecture. Same on ARM documentation. In ARM there is Thumb mode 16 bit this is why WORD is ALWAYS in real life reffered to 16 bit. I quote stackoverflow now "Changing the meaning of the term as extensions were added would have just been confusing, because Intel still had to document 16-bit mode and everything, and instruction mnemonics like cwd (sign-extend word to dword) bake the terminology into the ISA.x86 word = 2 bytes x86 dword = 4 bytes (double word) x86 qword = 8 bytes (quad word) x86 double-quad or xmmword = 16 bytes, e.g. movdqa xmm0, [rdi]. Also in the cqo mnemonic, oct-word. (Sign-extend RAX into RDX:RAX, e.g. before idiv) And then we have fun instruction like punpcklqdq: shuffle together two qwords into a dqword, or pclmulqdq for carry-less multiplication of qwords, producing a dq full result. But beyond that, SIMD mnemonics tend to be AVX vextracti128 or AVX512 (with optional per-element masking) vextractf64x4 to extract the high 256 bits of a ZMM register." - even AVX instruction sets uses 32,64bit as basic building blocks.

[@samuca101]

Actually, I think the most important thing is to understand the concept. If you grasp it, you'll know that 'double' will always be twice the size of the given 'word,' depending on the system and all these stuff. But i agree with u, would be better if he used the most common terminology, so it would be less confusing when you start programming...

[@goldfish8196]

THANK YOU!