[Oberon] SDRAM performance

[Skulski, Wojciech]

All:

It will be good to know how fast is SDRAM in practice. I googled for "sdram access time". I found lots of generic discussions where I could learn all the theory and few conclusions. I also found a few practical estimates. Here are the most relevant finds for the record.

1. Good online discussion. 

http://forum.gadgetfactory.net/topic/1934-sdram-controller-with-consistent-access-time/
There is a long discussion full of many interesting details, simulations, and corner cases. A good read. At the end of the discussion Matthew Hagerty concluded: "My design lets me read or write a word (16-bits in this case) every 70ns."

So 70 ns is the number I want to remember for a random fetch or store. Block reads are a different matter which is more related to video. There are many interesting thoughts by Hamster in that discussion concerning how to organize the video with SDRAM.

2. A PhD thesis in Electrical Engineering, 175 pages. 

Shao, Jun, "Reducing main memory access latency through SDRAM address mapping techniques and access reordering mechanisms",
Dissertation, Michigan Technological University, 2006.
https://digitalcommons.mtu.edu/etds/72

Like every dissertation, this one also starts with a background information which is worth reading IMHO.

Hope it helps,
Wojtek