Dual Port DDR SDRAM

[yy7d6]

Hi
Any knows of a Dual Port DDR SDRAM device?
Device that has seperate Read/Write address.

Thanks.

 

[Nico Coesel]

Hi
Any knows of a Dual Port DDR SDRAM device?
Device that has seperate Read/Write address.

I've never came across it. Given the principles of DRAM I doubt it
exists. What is your bandwidth requirement?

 

[[email protected]]

Hi
Any knows of a Dual Port DDR SDRAM device?
Device that has seperate Read/Write address.

Thanks.

Highly unlikely, there used to be a chip that would turn a standard
dram into dual port, went up to 1Mbyte IIRC. At least 10 years ago so
probably long obsolete.

 

[Roger Hamlett]

Highly unlikely, there used to be a chip that would turn a standard
dram into dual port, went up to 1Mbyte IIRC. At least 10 years ago so
probably long obsolete.

This is being done quite a lot on graphic cards, where the graphic chipset
itself (or in some cases a programmable gate array), is used to provide
such access. The problem of course is that most DDR memories are 'burst'
orientated devices, so the external buffer needs to be large enough to
support a full burst. Also the complexity is very different for a
sequential burst orientated read access (as needed on a video card),
versus a generic read. A lot will depend on what speeds are needed, and
the nature of the expected I/O. Some video DRAM's, offer the ability to
have two pages (or more) open at once, to simulate dual port operations.
Cypress do an interconnect family, to allow dual port access on a variety
of memories. A search for 'FullFlex' devices, may provide what is needed.

Best Wishes

 

[Michael A. Terrell]

Hi
Any knows of a Dual Port DDR SDRAM device?
Device that has seperate Read/Write address.

Thanks.

How about doing the old fashioned way with interleaved memory? Vital
Industries did the a long time ago with slow 1K * 4 DRAM in their
Squeeze Zoom digital video effects generator for live manipulation of
broadcast quality video. By careful timing and using two pages of video
ram it allowed one page to be updated while the second page was being
displayed live.

It was the first effective DVE system on the US market, but
apparently long gone from any broadcast use because of the cost to keep
it hot and running.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida