RAM Indexed guide?

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Ok guys, back on the ball today, I am trying to create a sort of an indexed version or quick reference guide of the RAM chapter, please have a look and tell me if there is anything here that is either missing or needs to be added as some of this stuff was not in the book, this is a combination of what's in the book and my own research on the net, therefore, what I would like to know in particular is, what's in here that will NOT come on the exam and what is missing that will come on the exam?

Please see the next post, thanks.

 

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Types of RAM Chips/Technology:

01] DRAM [Dynamic RAM]
-Needs to be refreshed so it's slow

02] SRAM [Static RAM]
-Faster, does not need to be refreshed. [Loses
data when power is turned off].


03] NVRAM [Non-volatile RAM]
-Differs from both DRAM and SRAM in that it retains
memory when power is turned off.

04] SDRAM [Synchronous Dynamic Ram]
-Memory speed is synchronized with the clock pulse
from the CPU.
-Synchronization enables SDRAM to PIPELINE read
and write requests.
-Pipelining enables SDRAM to accept commands at
the same time as it is processing other
commands.

05] SDR SDRAM [Single Data Rate]
-Original SDRAM standard, replaced by DDR SDRAM.

06] DDR SDRAM [Double Data Rate]
-Doubles the bandwidth of SDR SDRAM by
transferring data twice per cycle on both edges of
the clock signal.

07] DDR2 SDRAM [2nd generation of DDR SDRAM]
-Improves on DDR SDRAM by using differential
signalling and lower voltages to support
significant performance advantages over DDR
SDRAM.

08] RDRAM [Rambus DRAM]
-Developed by Rambus Inc.

09] EDO RAM [Extended Data Out]
-Needed to be refreshed much less often than FPM
but still slow.

10] SPD [Serial Presence Detect]
-Little chip installed on DIMM stick which provides
the system with all of the details about the DIMM
[size, speed and other more technical info].

11] ECC [Error Correction Code]
-Used in higher end systems, better than Parity.
-Most common in 168-pin DIMMS but must work
with MB designed to use it.

12] Registered DRAM
-Facilitates high-volume data flow in and out of
RAM, used in Servers and high-end workstations.

Types of sticks:

1] DIPPS [Dual Inline Pin Package]
-Very early DRAM chip which connected directly to
the MB via 2 rows of pins on either side.

2] SIPP [Single Inline Pin Package]
-First popular stick with onboard DRAM chips->30-pin

3] SIMM [Single Inline Memory Module]
2 Types:
a] 30-pin [8-bit data bus]-Made with contacts [not pins] to
prevent breakage.

b] 72-pin [32-bit data bus]

**When upgrading SIMMS, be sure to check for compatibility
before purchasing.

4] Parity chip->form of error-checking chip in an extra
1-bit chip on stick.

5] FPM RAM [Fast Page Mode]
-DRAM used for the first ten years in the PC industry
and did not use a clock.


6] DIMM [Dual Inline Memory Module]
-64-bit data bus.
-Dimm with 72 contacts will have 36 contacts on
each side.

**Comes in different sizes:
72-SODIMM
144-SODIMM
168-SDRAM
184-DDR SDRAM
240-DDR2 SDRAM

7] SODIMM [Small Outlet DIMM]
-For use in Notebooks.

**Comes in different sizes:
72->32-bit databus
144->64-bit databus
200->72-bit databus

 

Only small thing I'd point out:

SODIMM:

 

Noted, thanks! Would you believe that it took me roughly 6 hours [been at it since early this morning] to decipher, organize and put together the info in that post? What I don't get is why the need to remember the older stuff that is not being used today? I understand the need to know about it but what purpose does it serve for us to have to remebr this for the exam?

I mean, why would someone want to know how to replace a SIMM for example, who would have a pc that old nowadays?

 

You'd be surprised !!!

Seriously, how do you imagine it would look if you turned up to a PC that might contain legacy hardware, and you had literally no knowledge of even what it was ? Even a basic grasp of what was around (and theoretically still might be) is probably worth having for some tim eto come.

My 2 €

 

I wish I could find some of the older stuff, just to look at if anything, this way I will never forget what they look like making it easy for me to remember.

 

For what it's worth, SIMMS was a complete sh1t to work with iMHO - all that bending and inserting at awkward angles !!!

 

Tell me about it, the bane of my life.

 

If you, as a self-employed tech, were called to someone's house (with an appropriate callout fee) and found that the PC you were supposed to fix was so old you didn't know what you were looking at...

Not only could you not charge your customer, but (because to many people 'computers are computers') your reputation would be ruined.

Having said that, I think that you may be overdoing the 'depth' required for the A+.

Chill - the All In One goes in quite far enough for you to pass these exams.

J.

 

OK - my 2p worth.

EDO = Extended Data Out

Not a different refresh rate from FPM, but a different timing of the data lines, so that the data is valid longer in the cycle. Gave a better speed to the memory on motherboards that knew about it.

Otherwise a very good summary.

Harry.

 

@Juice142,
That's the problem Juice142, I don't know where that line is and also becuase the book does not explain everything to me so I have to go to the net for a lot of stuff.

@Harry
The EDO definition in my guide came from the book [page 135, bottom of the page, 2nd line from the bottom], please clarify this, thanks.

 

Another issue here guys, this time concerning SIMMS and DIMMS, I was thinking that the first letter in the word SIMM which means "single", suggests that these types of RAM sticks have the RAM chips only on one side of the stick hence the word, single. So this led me to think that DIMM sticks have the RAM chips on both sides of the sticks hence the first letter D [for Dual].

Further reading doesn't show this to be the case so can anyone please explain why or how the words "single" and "dual" are used to describe these sticks?

 

Single means that there is effectively only one line of *contacts*. The edge contacts on each side are the same.

Dual means that there are two lines of contacts, the contacts on the back are different to those on the front.

Single-sided and double-sided sticks (how the actual chips are positioned) are a different thing.

Harry.

 

Thanks Harry, got it now. Finally finished the RAM chapter and am very suprised I got 8 out of 10 correct and it only took me a few minutes, looks like the indepth research paid off? When I come back to this I will have to concentrate more on detemining how many sticks to use in different systems as that is giving me some trouble.

Now on to BIOS and CMOS, been waiting for this as now I can do some practical stuff!!

 

Oh, forgot to ask one more thing, is RIMM a "physical" chip or "part" of a chip or how can it best be explained?

 

Now I'm at home and can check the book....

I think he has got this bit wrong. And the picture is a cop-out!

Have a look at the following:
Wikipedia article
Brief comment in another dictionary
and a jargon buster page

Harry.

 

You have highlighted a very important point here. Doing such research always helps to make things stick. I find that when I hit something I'm not sure about my best course is to do just exactly what you did. Research, and then write up a summary.

On the number of sticks for different systems - an aide here is to know the 'width' of the main RAM sticks, and know the width of the processors. The number of sticks that have to be fitted at one time is the factor that joins those two values.

Harry.

 

As Meyers says in the book, the term RIMM is usualy applied to the whole stick, which has RDRAM chips mounted on it.

Harry.

 

So then my initial understanding is correct that the RIMM is indeed another type of memory "stick"?

 

Yes - and very different from the normal DIMM type. The main weirdness is that empty slots need to have a 'continuity' stick inserted.

RIMM is now fortunately very rare.

Harry.