Author Topic: sim72-fp - timing &C  (Read 248 times)

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Offline legacy

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sim72-fp - timing &C
« on: August 02, 2019, 09:25:01 am »
sim30's are simple, you have { ras, cas }, while sim72-fp's looks more complex and I am a bit confused because they have { { RAS0 RAS1 RAS2 RAS3 } { CAS0 CAS1 CAS2 CAS3 } } but I have seen designs where only { ras0 ras2 } are used, and connected together, while { ras1 ras3} are simply unconnected.

is there a clear and neat document about this?
 

Offline legacy

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Re: simm72-fp - timing &C
« Reply #1 on: August 04, 2019, 12:00:20 pm »
There are documents on 72SIMM around the internet but they are confusing. Yesterday I found in a street market a copy of "The indispensable PC hardware book", and from what I have understood, the assignment of RASx and CASx are made according to single-sided or double-sided. The book gives examples, and it seems that if the SIMM is singled-sided, then only RAS0 (lower 16 bits) and RAS2 (upper 16 bits) are used, while RAS1 and RAS3 are for the 2nd side of the double-sided SIMM card.

 


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