Lead programmer and co-owner of IfThen Software LLC.

Latest Media

We're sorry, but no images, videos or audio files have been added to this gallery.

If you would like to share media with the community, sign up and you can.

Blog RSS Feed Report abuse Latest Blog: DDR SDRAM Memory Bank

0 comments by InvisibleMan1 on Sep 28th, 2011

Because I'm getting into the section on memory (and some parts of yesterday's example made me curious, particularly the RAS-to-CAS delay) I have decided to research RAM again.  I did quite a bit of research in this area about a month ago, so a lot of this is review and should go by relatively quickly.

Data is stored in RAM in an array of bits called a "bank".










A horizontal line of bits make up a "word line" and a vertical line of bits make up a "bit line".











The array is split up into rows and columns.  A row is equivalent to a word line, so that's easy enough.  A column is made up of multiple contiguous bit lines, either 4, 8, or 16 depending on the architecture of the chip.  The number of bit lines which make up a column is the word width of the chip, or just simply the "width". This is usually written with an "x" followed by the width: x4, x8, and x16.













The number of rows depends on the generation of DDR and the "density" of the chip.  The density is the number of bits the chip has total across all banks.  The number of columns depends on the density and width of the chip.  The exact row and column counts for the possible densities and widths are specified by the DDR standard for the generation in question, although my experience is that you have to perform some calculations to find them.  Here is a table I put together of the row and column counts for the first generation of DDR:









Reposted from Invisiblegdev.blogspot.com

Groups
IfThen Software

IfThen Software

Developer & Publisher Invitation only

IfThen Software is an independent game development company with a focus on multiplayer games.

IndieDB

IndieDB

Official group with 1,898 members, open to all members

Indie games are changing the world, one giant pixel at a time. With Indie DB we aim to support independent developers and their games, by providing them...

Post a Comment
click to sign in

You are not logged in, your comment will be anonymous unless you join the community today (totally free - or sign in with your social account on the right) which we encourage all contributors to do.

2000 characters limit; HTML formatting and smileys are not supported - text only

Level
Avatar
Avatar
Offline Since
Aug 9, 2013
Country
United States United States
Gender
Male
Member Watch
Track this member
Accolades
IndieDB
Statistics
Activity Points
339
Rank
6,763 of 445,779
Watchers
1 member
Time Online
1 second
Comments
40
Site Visits
368
Profile Visitors
4,247 (1 today)
Contact
Private Message
Send Now
Email
Members Only
Auric
Auric friends since Jun 20, 2011
miotatsu
miotatsu friends since Jun 21, 2011
Lunatic_Hermit
Lunatic_Hermit friends since Jun 20, 2011
KoolerKii
KoolerKii friends since Jun 21, 2011
Acaceol
Acaceol friends since Jun 20, 2011
JaytheRogue
JaytheRogue friends since Jun 20, 2011
optimuspi
optimuspi friends since Jun 22, 2011
OneEyedWillie
OneEyedWillie friends since Jun 20, 2011
Leemh
Leemh friends since Jun 20, 2011