Mukashi
Creative Language in the Software Age

Adapted  from 101 Words I Don't Use by Paul Niquette
Copyright ©1995 by Paul Niquette, all rights reserved.

 
 
mukashi Of or pertaining to an item, usually information, that has not been used recently. Distinguished from oldest, least useful, or least valuable. [From Japanese mukashi, an introductory expression similar to the English "Once upon a time..." and connoting "Here begins a story which has not been told for the longest time..."]

Ironic, isn't it. Everybody has a memory, but nobody can explain how it works. Memories in brains differ from computer memories. Most people finally understand that. Brains learn, for one thing. You don't load them, they learn. They forget, too, even when the power stays on. Information inside a human memory fades away over a period of time. Not all information, though. Everybody has -- well, memories. Fond or otherwise.

Computers find information inside their memories mostly by addressing, sometimes by scanning, never by thinking. Brains work by association, we think. Units of information are coupled together by invisible, elastic bonds. There are dynamic processes at work, too. Circulating within a baffling neuronic structure are electrochemical impulses linking one idea to another -- by relevance or by common attribute or by whatever it is that nourishes familiarity. Brains recall a memory by consciously stimulating the content of the memory itself, or part of it. Stirring things up in there somehow. The recalling process reinforces the content, selectively preserving the memory.

  • Hence commercials and the marketing concept 'share-of-mind.'
Most memories are formulated from sensory information. Recollections, too, are often stimulated from outside. Three sense organs (eye, ear, and nose) are especially influential in accumulating memories and recalling them.
  • A face, a song, a whiff can set off an avalanche of associations.
Thus, the invisible, elastic bonds transcend the boundaries of the brain itself forming 'extrasomatic' (outside the body) links to other brains. Individual thinking has little sovereignty. People depend on Socialized Memory.

Brains work fast. We can recognize a face quicker than any computer. That will probably be true until well into the 21st century. With all their 'megaflops,' computers cannot process visual information fast enough to catch a fly ball -- cannot even tell a left hand from a right hand at a glance. Computers have an awful time recognize individual words embedded in continuous speech -- especially accented speech, heard over a noisy telephone line -- in realtime.

Our central nervous systems operate at a speed sufficient to keep us out of most kinds of trouble. But, when it comes to capacity, human memories, like everything else, are limited. Along comes writing, which makes for extrasomatic storage of information. Reading puts it back into a brain for processing. That takes time, though. Sometimes too much.

  • You can't expect your audience to be looking things up during your comedy routine (see Cultured Laughter).
  • You can't be reading a flight manual while landing a plane.
  • Nor a rulebook while umpiring.
As a practical matter, some items of information have to be kept handy within our brains. Others can be left outside in books. Or in computers, come to think of it -- and now at far-away websites. Computers, not surprisingly, have the same problem.

Only persons who have been living in a cave since the middle of the Twentieth Century would not know that computers have various kinds of memories. To describe three: First there is ROM, for read-only memory. ROM contains information which was built into the machine at the factory. ROM provides the computer primitive capabilities -- unchanging procedures for interpreting the keyboard, for shaping the characters on the screen, things like that. Human ROM, one might say, gave us two things...

  • the sucking instinct and
  • the fear of loud noises.
MukashiThe computer has a second kind of memory, called RAM, for random-access memory. This is most commonly the working memory into which the machine can electronically write variable data. Fast and transient, RAM is most like our own memory, although, as has already been said, not much.
    By the way, 'random' does not really mean 'without order' here. It means that the access time for any item in memory is the same as that for any other item, regardless of the order of accessing. A distinction worth noting, as we shall see.
Finally, there are the disks: 'floppies' (an embarrassing term that was first use to distinguish their flexible plastic media from the earlier rigid devices) and 'hard' disks (an equally embarrassing term that would be unnecessary had not someone coined 'floppy'). The typical floppy holds a megabyte or two of information; a half a dozen of them would hold the King James Version of the Bible; it takes hundreds to fill a typical hard disk. Enter the CD-Rom with the ability to replace stacks of floppies.
    Capacious indeed are disks -- but slow. Not as slow as looking things up in a book, but hundreds of times slower than RAM or ROM.
When the word 'cache' was first applied to memory, it needed to be pronounced in seven syllables: "cash, spelled c-a-c-h-e." The word was borrowed from the French cacher, to hide, and means 'hiding place,' a term familiar enough to explorers or pioneers for they used the word to describe the storage of provisions in the wilderness. {SideBar}

Cache memory is a special form of high-speed memory. The first cache memories appeared in the early sixties. That was back when computers filled a room and were still called "giant brains." RAMs were slow and expensive in those days. A RAM in the sixties comprised gazillions of tiny Cheerio-shaped cores made out of iron strung together with hair-thin copper wires, forming blocks the size of bricks. Core memories were slow, and the bigger you made them the slower they operated. The cache memory -- also called a 'cache buffer' -- made 'large core storage' operate faster. Later cache technology was used to buffer disks, increasing their effective speed.

The cache idea is based on an attribute of information itself, whether stored in chips and floppies or in brains and books. At any given instant, an item of information possesses a kind of 'vitality,' which is based on the likelihood that it will soon be needed either for computing or for thinking. Obviously, if an item in memory is about to be used, you want it to be available fast. Its access time is more significant than that of other items, which may not be needed for a long time.

  • A public figure reads his or her briefing documents just before a press conference.
  • A pilot reviews the chart for an airport just before initiating an approach for landing.
So too, in a computer, you would like to have the machine automatically upgrade information into higher speed memory just before it is needed. But how does a mindless machine figure out ahead of time which items should be thus 'promoted'? In other words, what does a cache do?

Computers, as mentioned earlier, don't make references to memory in a 'random' order, despite the R in RAM. If they did, cache buffering would not work. Instead, computers tend to access information in blocks (items in a record) and repeatedly (loops). The cache exploits both of these tendencies.

    For example, whenever the machine shows an interest in a given item by deliberately addressing it, the cache automatically promotes that and adjacent items -- often associated information -- into a high-speed form of memory.
A subsequent access is first directed to the cache, where, more often than not, the needed item will be found quickly. Only when the requisite information is not found in the cache, does the access get re-directed to the slower form of memory.
    Ah, you exclaim, but the cache will fill up!
True enough. As a practical matter, to be fast and cheap, cache buffers cannot be large. With the cache full, the whole machine decelerates. The pace is then set by the slowest memory devices, as accesses become increasingly re-directed to them.

Something has to give. Information must be thrown out of the cache ('demoted') to make room for newly accessed strings of items. The mindless machine must be endowed with the ability to decide which items to demote. What is the most 'reasonable' (to use a brain-like term) basis for that decision?

    Your intuition is probably telling the answer: Throw out the information that has been accessed the longest time ago.
That's roughly what your own brain does. Thus, do repeatedly accessed memories -- recollections -- stay fresh. Information not recalled often enough gradually will fade into oblivion.

As applied in web browsers, the 'cache' improves the apparent performance of the Internet -- which is essentially a gigantic disk memory distributed all over the world and accessed by a communications protocol.   The cache stores on your own hard drive a copy of each page and image as you acquire them from various websites.  If you click "Back", you will get that same information not from the web but from your own memory -- a whole lot faster. The cache software is smart enough to recognize that what you are accessing is available locally.  If you come back to cached pages or images before they get shoved out of your computer's memory, then you will enjoy the high performance that caches were invented to provide.
 

Nota bene: Websites have visitors, not residents. New visitors to a given site will suffer the download delay that I like to call 'network viscosity'.  A short time later, when they come back, visitors will reap the benefits the cache.  Now, the people who design or manage each website, naturally, come back again and again, each time enjoying cache-supported performance. This may be an explanation for some of the more viscous sites that sprinkle graphics and Java-jive all over your screen -- the worst being pages bombarding you with 'banner ads', which peremptorially fill up caches. Heck, the owners of those sites ('webmasters', they call themselves) don't ever see just how stultifying those delays can be to the first-time or infrequent visitor. Browsers provide commands for emptying the cache, and I think every website manager needs to give his or her own cache a good flushing every once in awhile.

Lack of creativity in computer language bothers me a whole lot, hence my habitual coining of neologisms, which seldom do more than torment my readers. {Footnote}  Still, inventing a new word is easy compared to instigating public usage. Better, it seems, to adopt a word that is already accepted -- preferably from English (like 'memory') or another language (like 'cache').

Consider the expression 'least recently used.' It is not the same as 'oldest.' An item that is 'least recently used' may be neither 'least useful' nor 'least valuable.' And 'obsolete' misses the point altogether. For 'least recently used', I found nothing that even came close. It's a little bit like trying to find an English word for chutzpah.

    Until a Japanese friend gave me mukashi.
But I was unable to stir up much interest in the term before moving on to other work. I shall never have an opportunity to say something like, "Performance of the cachecade memory depends greatly on the details of its mukashi algorithm."
 
 
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SideBar

One of my small contributions to cache technology, memorialized in U.S. Patent No. 3,938,097, is a hierarchical cache. Groaner Alert: I called it 'cachecade.' Hey, at least it was an attempt at inventive language. {Return}

Footnote

Check What's Not in a Name? for lamentations about the language of The Software Age. A related feature article in S:TM led to a memoir Softword: Provenance for the Word 'Software', which gives the ironic history of what is arguably the most important word coined in a hundred years.  The sophisticated reader may want to review Software Does Not Fail to become disabused of language-intensive cyber-myths. {Return}