|
Great confusion exists from the popular casual use of the
term "memory". Many people think the term "memory" is a
synonym for RAM, or for Disk space. Actually, the term
"memory" is a broad term which is neither a synonym for RAM
nor Disk space, though both may be used to provide "memory".
Apple defined Mac memory as a general term for the
logical working space where software operates; this
definition is illustrated by its use in the "About This Mac"
window of the first Mac. The "Total memory" space is
ususally provided by RAM (which is relatively fast), but may
also be provided by other hardware resources - like disk
space - using virtual memory techniques.
On computers where virtual memory is disabled ,
your "memory" is the same as your RAM; however, when virtual
memory is enabled your "memory" may exceed your RAM
(using other hardware resources - perhaps your disk space,
which is slower than RAM).
So "memory" is a broad term describing the space
available to software, meant to cover a wide variety of
configurations.
This is all so subtle...Why do we care?
The popular misconception that "memory" and RAM are the
same has been exploited by RAM Doubler literature to imply
that RAM Doubler (and thus virtual memory) does the same
thing as RAM Charger, and that RAM Doubler is functionally
different than Apple Virtual Memory. Because Connectix
substitutes the word "memory" in its literature where the
term RAM is appropriate, there is confusion in the market
about what RAM Doubler is, and why RAM Charger is
fundamentally different. In truth, since the issue appears
subtle, there might be confusion even if the proper words
were used; however Connectix appears to have gone out of
their way to add confusion rather than remove it.
RAM Doubler's virtual memory use of RAM in a dynamic way
is not the same as using memory in a dynamic way. The
issue is important because RAM Charger solves problems by
using memory in a dynamic was, that are not solved by just
having more traditional memory as provided by RAM Doubler.
By stating that they use memory in a dynamic way, when in
fact they mean RAM in a dynamic way, they mislead users into
thinking that RAM Doubler accomplishes things that it does
not
In fact, RAM Doubler propaganda is so convincing that
they have even fooled themselves into making false claims.
The FALSE RAM Doubler
(virtual memory) "Reclaim" Myth
RAM Doubler is documented to reclaim "memory" not in use
by an application (p11 of the RAM
Doubler Manual: RAM Doubler 2 dynamically reclaims any
unused memory and makes it available to run additional
applications). Since this is what RAM Charger does,
by allowing applications to start using less memory, many
people think the same thing is going on. Since this issue
is at the very core of RAM Charger's purpose, it is
understandably an important issue.
In fact RAM Doubler does not reclaim "memory".
This is apparent if you start two applications each having a
preferred size of half of your memory. In such case, you
will see that RAM Doubler documents the unused memory as
being reclaimed, yet none is available to start other
applications. For example, make two copies of the
application "SimpleText". Next, set the preferred size for
these applications to half the size of your Total Memory.
Now open both applications and examine About This Mac.
Here are screen shots of this example with
RAM Doubler. Note that
RAM Doubler says 31 megs are reclaimed to start
applications; however there is actually almost no memory to
start applications. This example may seem contrived, but it
is not. This example accurately represents the common real
world situations that RAM Charger was created to solve.
Of course, you must do this test with RAM Charger
disabled for these applications, since RAM Charger does
reclaim "memory". If RAM Charger is enabled for
SimpleText under the same configuration, each SimpleText
application will start small, yet each will have access to
the unused "reclaimed" memory. Here are screen shots of the
same sitatution with RAM
Charger. Note, in this case there really is 31 megs
available.
RAM Doubler does reclaim RAM in exactly the same way
Apple Vitual Memory does; however this does not help you in
the way they claim. It reclaims RAM this by taking the
"unused" memory and moving it to
"backing storage", making
"faster" RAM available for memory that is in use. This is
also what all virtual memory systems do, including Apple
virtual memory. What is important is that reclaiming RAM
does not allow application's to grow and shrink dynamically,
and thus they can still run out of memory prematurely. In
fact, even RAM Doubler's own liturature suggests that you
start applications in the same fixed "preferred" sizes you
used before RAM Doubler.
All of this is not to imply that virtual memory is not
valuable, only that it does not do what RAM Charger does.
Each technique has its own value.
More details about RAM
Memory is not a synonym for "RAM", which is a very
specific term which refers the physical hardware. RAM refers
the volitile physical hardware which is able to store and
retrieve information relatively quickly. RAM stands for
Random Acess Memory, meaning that computers can store and
retrieve information at any random location. The memory is
volitile, since the information stored is lost if power is
turned off.
Applications can only operate from within real RAM, since
the CPU can only obtain instructions from RAM. When virtual
memory is disabled, all "memory" is in real RAM. However,
when virtual memory is enabled, some "memory" is in real RAM
and other memory is in "backing
storage" since there is insufficient RAM. As a result,
to perform operations in backing storage all processing must
halt while the operations are moved from backing storage
(relatively slowly) into real RAM. This is why virtual
memory can cause slowdowns, or jerky operation.
More details about Disk space
Memory is not a synonym for "Disk space", which is
a very specific term which refers the physical hardware.
Though it is technically correct to call disk space
"permanent memory", or "disk memory", or some other
"qualified" kind of "memory", "memory" by iteslf refers to
the working space for applications as shown in the Finder's
"About This Mac" window and not your general hard disk
storage space. Unfortunately, this leads to confusion,
allowing users to think "memory" may refer to their disk
storage space.
Disk storage space is where applications and information
are permanently stored. Also, disk space is often used as
"backing storage" when virtual
memory is enabled. Disk memory retains the information even
when no power is applied to the disk, and disk space is
cheaper than RAM. However, accessing information stored on a
disk is magnitudes slower than accessing information in RAM.
| 
