-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
1. Can you explain Fast Page/EDO RAM?
Reader: I wish to upgrade a Pentium 133
MHz rig having only 16MB of RAM by adding two 32MB
72 pin EDO SIMMS. I have noted some suppliers list
these as Fast Page/EDO, quoting a speed in
nanoseconds. Is this crucial?
Computer Doctor: You should install the
type of memory supported by your system, and most
P133 systems (depending on the motherboard
chipset) can use either FPM or EDO memory of a
given speed (EDO is a little faster). You can
normally install faster memory than is required,
however you shouldn't install slower memory than
your board requires.
I recommend you purchase memory upgrades from
http://www.crucial.com. They can suggest the
proper memory guaranteed to work in your system.
Note that FPM and EDO memory is obsolete, so don't
be surprised if you have to pay more than double
for that type of memory as compared to much faster
modern SDRAM! In many cases I feel that it simply
isn't worth installing expensive obsolete memory
in otherwise relatively worthless obsolete PCs,
opting for a motherboard/CPU/memory upgrade
combination instead.
2. Will PC100 SDRAM work with a Pentium 4
processor?
Reader: I was wondering how long you
think that PC100 SDRAM will be a current memory
type? Do you think if I bought another 128MB SDRAM
that I would be able to use it with a future CPU
such as the Pentium 4 series?
Computer Doctor: No, PC100 has just
become obsolete as far as being "state of the
art". Most newer systems today need either PC133
SDRAM, PC800 (RDRAM), or PC1600/PC2100 (DDR-SDRAM).
The Intel 850 chipset (currently the only chipset
for the Pentium 4) supports only RDRAM, however
Intel and others are busy working on new chipsets
that will support DDR-SDRAM. There probably won't
be a Pentium 4 chipset that supports either PC100
or PC133 SDRAM since they are too slow for that
processor.
3. Can I install PC133 memory in a system that
requires PC66 or PC100 memory?
Reader: I am planning to upgrade my
PC's memory. I currently have a 128MB PC100 memory
module. I have one slot free. I want to get a
256MB module, giving me 384MB. Will Windows 98SE
work with mixed-size memory modules? And, can I
use PC133 instead of PC100 memory modules?
Computer Doctor: Win98 SE will handle
any memory that is compatible with your
motherboard/chipset. And, you can use PC133 in
place of PC100 or PC66 SDRAMs. Since PC133 modules
are used in many new PCs, buying PC133 modules
today allows you to reuse your memory upgrade in
the future on new machines. That's why I have only
been purchasing and installing PC133 memory in my
systems lately, even for those that only require
PC66 or PC100 memory.
4. Some of my DIMM sockets
don't seem to working properly. Can you help me
track down the cause of this problem?
Reader: I have a board with three DIMM
slots. I have two 128MB PC100 tested DIMM modules.
Either one works OK alone in slot 1, but they will
not work together as 256K in any combination of
slots 1 and 2 or 1 and 3 even though made by the
same manufacturer. My system is using all current
drivers, 300 watt power supply and good cooling.
Do you have some possibilities I could test?
Computer Doctor: Check these
possibilities:
-
Memory that's not really PC100-compliant.
How do you know these are really PC100 memory
modules? There is a lot of bad or counterfeit
memory floating around, so if you didn't get
these from a reputable source they could be
suspect. Note that real PC100 modules
require 8ns (8 nanosecond) chips or faster.
Unless the chips have been remarked (which does
happen) you can tell the speed of the chips by
decoding the part numbers on them.
-
Problems with your motherboard
configuration. If your board supports memory
timing parameters in the chipset setup screens
in the BIOS Setup, then try resetting to factory
defaults or in general slower settings.
Also make sure your motherboard has the
latest BIOS, and that it does support the type
and size of modules you are installing (check
the documentation).
-
Defective PC100 memory. Replace your modules
with known-good modules and retest.
-
Defective motherboard. If you have
known-good modules, the memory timing parameters
are correct, and it still fails, then you
probably have a bad board. Replace the
motherboard with a known-good spare and retest.
5. How do current memory
modules, such as PC100 and PC133, compare to PC66
modules in terms of nanoseconds?
Reader: I remember when memory modules
were rated by nanosecond (ns) speeds such as 70ns,
60ns, etc. How do the current PCxx speeds such as
PC100, etc. compare to ns speeds? I want to make
sure that when a buy a so-called "PC133" module
that its memory chips are the right speed.
Computer Doctor: The current SDRAM
standards are PC66, PC100 and now PC133. Note the
speeds generally work out as follows:
PC66 = 10ns (100MHz)
PC100 = 8ns (125MHz)
PC133 CL3 = 7.5ns (133MHz)
PC133 CL2 = 7ns (143MHz)
In other words, to be rated as a PC100 module,
the chips will be rated 8ns, which technically
equals 125MHz. PC133 CL2 (Column Address Strobe
[CAS] Latency of 2 cycles) memory is generally
rated 7ns, which technically equals 143MHz.
6. Can you explain the differences between
segment addresses and linear addresses?
Reader: Just for clarification: For
IDE/ATAPI CD-ROM and tape drives, are their
respective controllers on the devices itself or on
the motherboard? Also, a book I read at the
library mentioned that you must have an ATAPI
driver when installing a CD ROM drive. Is this
true?
Computer Doctor:Unfortunately anything
else I could reference is much more technical and
even harder to understand! I often explain this
further in the PC hardware classes I teach, but
currently we are running them only for larger
companies.
The best analogy is to think of a hotel. Each
floor can be thought of as a segment, and the room
number on the floor is the offset. Thus room 541
would be segment 5, offset of 41. The confusion
comes from the fact that both segment and offset
overlap in the PC. So to be more accurate, my
analogy would have to say segment 50, offset 41 to
refer to room 541. This means that technically you
could start a new segment every 10 rooms. Thus it
would be possible to refer to room 541 also as
segment 54, offset 01, or segment 52, offset 21,
or segment 53, offset 11, etc.
I hope this helps, memory is the most difficult
aspect of the PC to fully understand. Thanks for
your interest, and I hope you like the new
upcoming 10th anniversary edition! The memory
chapter has been significantly enhanced.
7. Should I install parity memory?
Reader: I keep wondering if I should
replace the non-parity SIMMs (4 x 16 x 32) with
the (4 x 16 x 36) I have bought to see if this
makes any difference.
Computer Doctor: It's probably not worth
replacing what you have, but make a pact with
yourself that your NEXT system must have ECC.
8. Should I believe salespeople when they tell
me the parity memory isn't necessary?
Reader: All the computer stores in town
tell me that the "new systems" don't need parity
memory. I know that it is a newer memory
technology, but some stores carry it and some
don't. When I ask questions about it, no one can
explain it to me. So, how can they tell me I don't
need it if they can't explain it? I always thought
parity memory was better/safer because at least
one gets a warning if you get a parity error and
you know something is "flaky." Is this true?
Computer Doctor:They are blowing smoke
about something for which they clearly have no
knowledge. Don't believe anything a computer
salesman tells you. That's my motto.
Get the parity memory.
Even better than parity (for Pentium and higher
systems) is ECC, which uses the same parity memory
but to a higher level, it will not only detect
errors, but can correct them on the fly, greatly
improving overall system reliability and
integrity. Parity (or now ECC - Error Correcting
Code for Pentium and beyond) memory is all I will
use in my systems.
9. What does PNY mean in reference to SDRAM?
Reader:Can you briefly describe what
the new "PNY" designation means with regards to
SDRAM?
Computer Doctor: It means the modules in
question were made by:
PNY Technologies
299 Webro Rd
Parsippany, NJ 07054
Tel. 973-515-9700
Fax 973-560-5590
They are a fairly large manufacturer of SIMMs
and DIMMs.
10. Can you explain re-mapping unusable Upper
Memory into extended memory?
Reader: In your book, you write about
how otherwise unusable Upper Memory is made usable
by re-mapping it into extended memory. I can't see
how this produces more available memory if it
takes extended memory out of use. I think I am
missing something. Is it that it is given an
address at what would be the beginning of the next
(but nonexistent) memory chip?
Computer Doctor:
Actually you are re-mapping extended memory into
upper. You don't have more total memory, in fact
the whole procedure uses up some memory overhead
to load the drivers and such so technically you
are losing memory. What is happening though is
that you are placing memory in an area where
16-bit (DOS based) drivers can use it. Only 32-bit
drivers and software can load into the second
megabyte and beyond.
11. Can EDO and FPM be mixed on the same
system?
Reader: On page 803 (of the 8th
Edition) you state that EDO RAM can be used in a
system designed for FPM SIMMs and vice versa, with
no ill effects. Therefore, when I had an
opportunity to purchase a 16MB EDO SIMM to replace
my two 8MB FPM SIMMs ( one of which was static
damaged. I did so. It works great. What you did
not mention is whether or not the two types can be
mixed?
Computer Doctor: If your system will use
EDO with no problem then they can also be mixed
with no problem. Most systems will allow mixing
bank by bank, however some may not allow mixing
WITHIN a single bank. Remember on a 486 system
without interleaved memory, a single 72-pin SIMM
constitutes a single bank, while on a Pentium
system two SIMMs make a single bank.
12. How do I identify DIMMs that are
compatible with my motherboard?
Reader: After installing an additional
a 32 MB DIMM, I discovered that the computer
wouldn't recognize the chip. Even just using new
chip alone, it still doesn't work. Later, I
learned that my Intel Tigereye motherboard only
supports certain memory types (for example, it
does support 2CLK). However, it does not support
4CLK SDRAM memory. Nobody can tell me the
difference or how to identify between the two. Can
you?
Computer Doctor: These minor types of
incompatibilities point out why it is important to
purchase DIMMs only from reputable manufacturers
with knowledge of the standards and the products
such as Kingston, Micron (Crucial), Smart, Simple,
Viking, etc. They would have asked you which
motherboard the memory was going to be used in and
then only shipped you DIMMs, which would have been
compatible.
The problem is that the VX chipset was one of the
first chipsets on the market to support SDRAM
DIMMs at all, and as you now know, is lacking in
several areas. I don't know what you paid for your
32M DIMM, but you should be aware that you can get
a brand new Pentium motherboard with the (newer
and better) 430TX chipset for about $70 that
should support both of your DIMMs. In other words,
you may be better off replacing your motherboard
than your DIMM. The new board will also have a
more modern BIOS, a higher performance IDE
interface, and many other improvements over your
existing board.
The problem with your chipset (and board) is
that there are a total of 4 clock signals
available to SDRAM DIMMs, but your chipset only
supports two of them. The additional clock signals
are required by DIMMs which have more physical
chips onboard. This effectively means that you
can't use DIMMs with greater than 10 SDRAM chips
on them.
CK0 (pin 42), CK1 (pin 125), CK2 (pin 79) and
CK3 (pin 163) are the four clock signals. CK0 is
used in all SDRAM DIMM configurations. In general
(with a few possible exceptions) CK1 is used in
all DIMMs containing greater than five SDRAM
chips, and CK2 - CK3 are used in configurations
with greater than 10 SDRAM chips. All of the
unused clocks are terminated with a capacitor to
approximate a load of four to five SDRAM chips.
For all clocks that drive less than four SDRAMs a
padding capacitor is added such that the total
clock net approximates a load of four to five
SDRAMs.
Note that Intel has created standards for SDRAM
and SDRAM DIMM design for PCs. For more
information on these standards, see:
http://developer.intel.com/technology/memory/index.htm
13. Why won't OS/2 load after installing more
memory?
Reader: I ran into problem adding
faster memory to a system when I tried to load
OS/2 version 2.1. It refused to load. I had a 16
MB, 70 ns SIMM and added another 16 MB, 60 ns SIMM
(my dealer did not have 70 ns on hand and gave me
the faster SIMM for the same price). Windows NT
Workstation version 3.51 loaded and worked fine,
recognizing 32 MB, but OS/2 gave me some bad
memory messages. I had to return the 60 ns SIMM to
the dealer and get a 70 ns one, then OS/2 was
satisfied.
Computer Doctor: I've always said that
OS/2 was the best memory test program I had ever
seen.
That is because I think it works the memory
more than other programs. As far as your problem,
there could have been problems due to differences
in the memory refresh design (2K or 4K refresh)
between the chips you had and the ones you added
which affected this rather than the speed. Also
the SIMM you had could have been bad or marginal.
If the same type of memory had been used the speed
should not have made any difference.
14. What is SGRAM?
Reader: Lately, I've been hearing about
SGRAM being used on some video cards for the last
2 or 3 months. I don't have any clue what it is
and nobody I've talked to has known either. Can
you explain it to me?
Computer Doctor: The full name is
Synchronous Graphics RAM. It is a type of SDRAM
which is dual ported for video cards. Dual ported
is so the video chipset and DAC (digital to analog
converter) can both read the data from the chips
at the same time. The synchronous part means that
the memory runs at the true board clock speed
(33MHz if it is a PCI board), and thus can
transfer data in sync. with the system using less
wait states.
15. What kind of memory retains information
after the computer is powered off?
Reader: Do you know of any memory that
is programmable and still retains the info after
its powered off (something like EPROM, EEPROM or
CMOS).
Computer Doctor: EEPROM and or Flash ROM
does exactly that. I have a 20MB flash memory card
which I use in my laptop PC for temporary working
backup while on the road (I can backup up to 20MB
of my current working files), and also in my
digital camera. It stores data permanently without
power, and yet works just like a hard disk, except
faster! The 20MB PC-Cards (PCMCIA) are about $200
now I believe. You can get them in capacities up
to 100MB or more!
16. I'm curious about the
advantages/disadvantages of using ECC memory.
Reader: A technician at a major memory
vendor (Crucial.com) told me that I wouldn't need
ECC memory unless I was running very data-critical
applications, and I would also slow down my
computer if I installed ECC memory. Did I get the
straight scoop, or is ECC memory worthwhile?
Computer Doctor:Putting the chipset into
ECC mode does slow down memory access by a very
small (i.e. imperceptible) amount due to the time
added for the ECC generation and checking. I still
use ECC memory on all of my systems where it is an
option. The small additional cost is worth the
fewer hassles and less crashes. Everything I do on
a computer is a "data critical application". After
all, I don't play games: computing is my business.
And, as memory densities and capacities increase,
so does the possibility of soft (i.e. cosmic-ray
induced) errors. That's why I continue to purchase
and install ECC memory for my systems which
support it (i.e. my laptop doesn't). I am into
'overkill' - being better safe than sorry. That's
why I also install much larger power supplies than
the minimum required (such as a 450 watt where a
250 watt would be adequate).
17. Virtual Channel Memory (VCC-133) - is it
really faster and more energy efficient than
PC-133?
Reader: I recently bought an Asus A7V
motherboard which supports either PC-133 or VC-133
SDRAM modules. The VC-133 SDRAM is 50% faster and
30% less power hungry, but I haven't heard very
much about this Virtual Channel Memory. Is it
really better?
Computer Doctor: VC (Virtual Channel)
memory is a form of SDRAM developed by NEC (now
Elpida Memory) in 1998 that incorporated high
speed registers called channel buffers to allow a
higher transfer rate than standard SDRAM.
Unfortunately, this type of memory never really
caught on, and is only supported by a few
motherboard chipsets (none from Intel or AMD), and
only one company largely makes all the VC memory
(NEC). It has already been superceded by newer and
faster memory technologies such as RDRAM or DDR
SDRAM. Because it's rare and the fact that RDRAM
and especially DDR have much greater performance
and are supported by many more motherboards, I
wouldn't recommend VC memory at this point.
18. I'm trying to upgrade my SIMM memory but
can't get the PC to recognize the new chips, why
not?
Reader: I tried to upgrade my memory by
installing a 64MB SIMM module; my PC already has
two 32MB SIMMs. The PC did not detect the
additional RAM. I was advised to remove the SIMMs
altogether and install a 128MB DIMM. The PC still
did not detect it. What am I doing wrong?
Computer Doctor:On Pentium and later
systems using SIMMs, SIMMs need to be installed in
matched pairs. DIMMs can be used one at a time,
but most systems don't allow mixing SIMMs and
DIMMs. Some of the early motherboards with DIMM
sockets are very picky about the type of DIMMs you
install, so even if you remove all the SIMMs, you
probably don't have the correct type of DIMM for
your system.
I recommend you visit
http://www.crucial.com and use their on-line
system to locate the proper memory for your
specific system. All you need to do is input the
system make and model, or if you know the
motherboard make and model you can use that too.
Note that with most older Pentium systems, adding
more than 64MB will dramatically slow the system
down since memory past that point can't be cached.
In most cases with a system as old as yours, I'd
recommend you either leave only 64MB of RAM in the
system or upgrade the motherboard, processor and
memory all at the same time.
19. So many types of RAM, what's the best?
Reader: AMD supports SDRAM and DDR
SDRAM, while Intel currently supports SDRAM and
RDRAM, and will soon be supporting DDR SDRAM.
There is another RAM called SLDRAM which is also
protocol-based (as is RDRAM) and is an open
architecture. Its performance is as good as any
DDR SDRAM and RDRAM. When will this RAM will come
to market? Which RAM types are best?
Computer Doctor: Both RDRAM and DDR SDRAM
are better than SDRAM (up to twice as fast).
Currently RDRAM is 3 to 5 times more expensive
than DDR SDRAM. That makes DDR SDRAM clearly the
best value.
I believe DDR SDRAM will be the prevailing
standard unless the price of RDRAM falls
considerably. At least until QDR (Quad Data Rate)
SDRAM debuts. QDR will be the likely successor to
DDR in a couple years.
As for SLDRAM, if you check the SLDRAM website at
http://www.sldram.com, you'll see they stopped
issuing press releases after it was supposed to be
released in 1998. Apparently this type of memory
'died' before it was ever born, and no motherboard
chipsets support it either.
20. Can I add a DIMM chip in addtion to my
SIMM chips on my Microstar International
motherboard?
Reader: I have a Microstar
International motherboard MS-5145 ver 2.1 and its
memory configuration includes 2 SIMM banks (each
with 16 MB) and 2 DIMMS (currently empty). Can I
add a 32 MB DIMM and leave the SIMMS thus giving
me 64 MB or do I have to only use DIMMS or only
SIMMS?
Computer Doctor:According to the
documentation on the MSI site
http://www.msi.com.tw/support/manual/oldmanual.htm,
you can't use SIMMs and DIMMs together. If you do
dispose of your SIMMs and switch to DIMMs you'll
also have to reset the memory voltage jumpers J1
from 5V (SIMM voltage) to 3.3V (DIMM voltage). You
do this by moving the two jumpers from 1-3 to 3-5
and from 2-4 to 4-6.
Note that virtually all boards with both SIMM and
DIMM sockets can use only one or the other at a
time. I recommend you purchase your memory from
, they are the memory
vendor I recommend the most. Note that your
motherboard uses the Intel 430TX chipset which
only supports caching up to 64MB of RAM. This
means that if you install more than 64MB you will
slow the system down dramatically.
Rather than throw away 32MB worth of SIMMs just so
you could purchase a single 64MB DIMM (which will
be somewhat of a waste of money as you'll only
gain 32MB in the process), I would recommend
trashing this board and instead getting a new
Socket 370 or Socket A motherboard, Celeron or
Duron processor, and 128MB of SDRAM or DDR DIMMs.
You could upgrade to 700MHz and 128MB of RAM with
a new board for a total of $300 or so (including
the board, processor, and RAM). See
http://www.tccomputers.com or
http://www.aberdeeninc.com for more
information.
21. What kind of DIMM should I look for to
accomodate my Pentium Motherboard/133MHz CPU?
Reader: I have a Pentium Motherboard
with a Pentium 133MHz CPU (Not MMX) Intel i430VX
PCI Chipset. The system reads PC100 64MB DIMM as
16MB and reads PC100 128MB DIMM as 32MB. As a
result my 192MB of actual RAM is being read as a
total of just 48MB. Can you recommend the kind of
DIMMs that I should be looking for? This
motherboard has 2 DIMM slots & 4 72 pin SIMM
slots.
Computer Doctor:The 430VX chipset was the
first chipset on the market that even supported
SDRAM at all, and that support was problematic at
best. Among other things it required DIMMs with a
special clocking requirement, and couldn't use
high capacity versions, which is why it's
incorrectly reading your large DIMMs as the
smaller DIMMs it was designed to use. See
http://www.crucial.com; Crucial's web site
should have the type you need and will know what
works in that board.
Note that you cannot use SIMMs and DIMMs
simultaneously (remove any SIMMs when you install
the DIMMs), and I doubt that the 430VX chipset
will handle 128MB DIMMs at all and may not work
with even 64MB DIMMs.
Also note that the 430VX won't cache any memory
past 64MB, which means if you install any more
memory than 64MB, you will dramatically slow down
your system because the cache will be partially
disabled. Bottom line, I'd recommend you NOT
upgrade the memory in that board, since it will be
expensive and you'll get little benefit. With
hardware that obsolete you should be thinking
about either replacing the motherboard, processor
and RAM as a unit, or possibly the entire system
with something new.
|
