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PostPosted: Sat Apr 07, 2007 12:58 am 
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Since kernal34 asked the question about asynchronous SRAM, I thought I'd throw this one out too, for those familiar with DRAM.

I've never paid much attention to DRAM. Is there a DRAM IC or module of 8Mx8 or 16Mx8 which:
    does not need a DRAM-management IC (unless it's already part of the module)
    does not need software column-strobing
    has 8 or 10ns truly random access (not just 8ns after a burst is started)
    preferably 5V
    has no more than say 10pF loading per pin?
5V monolithic SRAMs seem to top out at 512KB, and 3V ones at 2MB. It'd be nice to be able to get a whole lot more for a 20MHz '816 computer all in one IC or module that presents a light bus load and requires no wait states, no adding to the interrupt load for software column strobing or otherwise upsetting the processor's critical timing in real-time applications, etc.. If it were 9 or 16 or 18 bits wide, that would be fine too-- I just wouldn't use the extra bits.


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PostPosted: Sat Apr 07, 2007 8:32 pm 
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Joined: Tue Nov 18, 2003 8:41 pm
Posts: 250
Quote:
I've never paid much attention to DRAM. Is there a DRAM IC or module of 8Mx8 or 16Mx8 which:
    does not need a DRAM-management IC (unless it's already part of the module)
    does not need software column-strobing
    has 8 or 10ns truly random access (not just 8ns after a burst is started)
    preferably 5V
    has no more than say 10pF loading per pin?


I haven't kept up with this stuff, but try googling "pseudo static ram"
or "psram"

however, I don't think they make ANY DRAM that is that fast.


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PostPosted: Sun Apr 08, 2007 3:02 am 
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It is the lack of sufficiently large and easy to use SRAM packages that forced me into using FPGA technology for the Kestrel 2, since no significant amounts of RAM can be acquired without it being SDRAM, which requires a very complicated state machine to properly initialize it at system startup.


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