It Made Sense in 1978

Programming in the 21st Century - James Hague - March 04, 2010

Whenever I see this list of memory cell sizes, it strikes me as antiquated: 

BYTE = 8 bits
WORD = 16 bits
LONG = 32 bits

Those names were standard for both the Intel x86 and Motorola 68000 families of processors, and it’s easy to see where they came from. “Word” isn’t synonymous with a 16-bit value; it refers to the fundamental data size that a computer architecture is built to operate upon. On a 16-bit CPU like the 8086, a word is naturally 16-bits.




Now it’s 2010, and it’s silly to think of a 16-bit value as a basic enough unit of data to get to the designation “word.” “Long” is similarly out of place, as 32-bit microprocessors have been around for over 25 years, and yet the standard memory cell size is still labeled in a way that makes it sound abnormally large.




The PowerPC folks got this right back in the early 1990s with this nomenclature: 

BYTE = 8 bits
HALFWORD = 16 bits
WORD = 32 bits

That made sense in 1991, and it’s still rational today. (64-bit is now common, but the jump isn’t nearly as critical as it was the last time memory cell size doubled. The PowerPC name for “64-bits” is “doubleword.”)




Occasionally you need to reevaluate your assumptions and not just cling to something because it’s always been that way.



Categories: Blogs  Programming in the 21st Century  

Comments

anonymous avatar

На сайте компании “АВЕРС” http://www.aversnpk.ru/ представлена информация о фототерапевтических устройствах компании “АВЕРС”. Физиотерапевтические приборы компании: соска “Доктор Свет”, “АВЕРС-Душ”, “АВЕРС-Лайт”, “АВЕРС-Сан”. Соска “Доктор свет” - лечение ОРЗ, лечение ОРВИ у детей раннего возраста. Физиотерапевтический прибор “Доктор Свет” (патент № 55293) эффективен при лечении и профилактики ОРЗ, ОРВИ, лечении кашля.

Posted by avers on 05 Mar 2010 at 18:47



 
anonymous avatar

http://www.web-bpro.ru/ Веб-студия “Бизнес-Профессионал” - создание интернет сайтов, создание интернет магазина по разумным ценам, быстро, качественно, профессионально. Создание интернет сайтов с индивидуальным дизайном сайта. Поддержка и продвижение сайта в интернете.
Компания Бизнес-Профессионал оказывает риэлторские услуги в сфере коммерческой недвижимости: аренда офисов, складов, магазинов в Москве. http://www.business-pro.ru/

Posted by Сергей on 05 Mar 2010 at 18:50



 
anonymous avatar

I always just thought of a “word” as whatever the word size of a specific machine’s word was. So, machine specific, rather than being “right” or “wrong” if it’s different between machines.

Posted by Paul Bonser on 07 Mar 2010 at 01:32



 
anonymous avatar

I agree that word size is machine specific, but it becomes language-specific once it’s in a language definition. In Java an int is defined as 32 bits, and a long as 64 bits. But now the computers I use most often are 64 bit machines, and so there is a case for considering an int 64 bits and for introducing a longlong type, though there is BigInteger. Changing the definition of int would introduce incompatibilities such as the C and C++ folks are used to. This isn’t an issue on planet Erlang, though, because the coupling between the integer type and the underlying architecture is weaker.

Posted by Jeff Martens on 09 Mar 2010 at 16:25



 


Add comment

Name:

Email:

URL:

Smileys

Remember my personal information

Notify me of follow-up comments?