Designing a memory system

johnL · 30-09-2008, 08:02 PM

I am new to the hardware realm and am having difficulty with some work i've been assigned from a text book. Any help would be greatly appreciated.

Question:
--------------------------------------
Given a supply of 4 bit wide DRAM chips containing 2^29 locations, you are asked to design a memory system for a machine with 8 DIMM slots where each DIMM slot provides word (32bit) wide data transfers and has a capacity of 2GB. How many chips are required per DIMM?

Given a 32 bit address: <A31 A30 … A2 A1 A0>, which bits will be used to:
a) select a location on a given chip,
b) select between chips on a DIMM and
c) select between DIMM slots.

Real-world memory systems commonly allow you to choose between different sized DIMMs (e.g. you can plug in either 1GB or 2GB DIMM sticks). How does this affect the address bits used in selecting chips, DIMMs, etc.? How do you think this is done?
----------------------------------------------------

I'm not worried about the rest of the question yet, i'm still stuck on the first part (opening paragraph), "How many chips are required per DIMM?".

I'm not looking for handouts, just something to get me started or point me in the right direction. Thanks in advance!

Big B · 01-10-2008, 03:52 PM

Well, based on what I've seen, it would depend on how much space is per individual RAM chip. However, I think, and don't quote me since I am not an engineer, but since the chips are 4-bits wide and you need to get to 32-bits, 32/4=8. For the other stuff, I'm not sure.

johnL · 01-10-2008, 05:57 PM

Well that's partially right. In order to form a word i'd need 32/8 = 8 chips. But i'm going to need a certain amount of rows of 8 chips. That's when the address space and locations come into play, and where i'm lost.

30-09-2008, 08:02 PM	#1 (permalink) Top
johnL Geek Trainee Join Date: Sep 2008 Posts: 2 Status: Offline	Designing a memory system I am new to the hardware realm and am having difficulty with some work i've been assigned from a text book. Any help would be greatly appreciated. Question: -------------------------------------- Given a supply of 4 bit wide DRAM chips containing 2^29 locations, you are asked to design a memory system for a machine with 8 DIMM slots where each DIMM slot provides word (32bit) wide data transfers and has a capacity of 2GB. How many chips are required per DIMM? Given a 32 bit address: <A31 A30 … A2 A1 A0>, which bits will be used to: a) select a location on a given chip, b) select between chips on a DIMM and c) select between DIMM slots. Real-world memory systems commonly allow you to choose between different sized DIMMs (e.g. you can plug in either 1GB or 2GB DIMM sticks). How does this affect the address bits used in selecting chips, DIMMs, etc.? How do you think this is done? ---------------------------------------------------- I'm not worried about the rest of the question yet, i'm still stuck on the first part (opening paragraph), "How many chips are required per DIMM?". I'm not looking for handouts, just something to get me started or point me in the right direction. Thanks in advance!

01-10-2008, 03:52 PM	#2 (permalink) Top
Big B HWF Godfather Join Date: Dec 2001 Age: 28 Male Posts: 9,636 Times Helpful: 585 My Mood: Devilish Status: Offline My Computer	Well, based on what I've seen, it would depend on how much space is per individual RAM chip. However, I think, and don't quote me since I am not an engineer, but since the chips are 4-bits wide and you need to get to 32-bits, 32/4=8. For the other stuff, I'm not sure. __________________ Hardware Forums\|HWF Rules\|My DVD's\|PSU FAQ\|HWF Folding Team\|2CPU

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01-10-2008, 05:57 PM	#3 (permalink) Top
johnL Geek Trainee Join Date: Sep 2008 Posts: 2 Status: Offline	Well that's partially right. In order to form a word i'd need 32/8 = 8 chips. But i'm going to need a certain amount of rows of 8 chips. That's when the address space and locations come into play, and where i'm lost.

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