Dual Port RAM/VRAM

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Hi guys, I'm looking for VRAM chips for breadboard the larger the better.  Do yous know of any suppler/chips?

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I think you find anything half modern will be BGA and the clock speeds involved will preclude a breadboard.

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What do you want to do ?  Maybe you don't need VRAM and can get by with something else.

 

Way back in the day when VRAM was a thing for high end video cards they all came in SOJ packages.

 

You can still get fast 15nS static ram in skinny DIP.  You can interleave access to it and have two things access it at once at pretty high speed.

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Fianawarrior wrote:
the larger the better.

the XL741 is pretty big:

https://www.evilmadscientist.com/2014/the-xl741/

 

and they also have an XL version of the 555.

But you might have some trouble in fitting those on a breadboard.

 

These things https://en.wikipedia.org/wiki/Video_RAM_(dual-ported_DRAM) seem to be obsolete for over 20 years now and they would never have fitted a breadboard.

The same wikipedia page may have a hint for a replacement:

In the late 1990s, synchronous DRAM technologies gradually became affordable,
dense, and fast enough to displace VRAM, even though it is only single-ported
and more overhead is required. Nevertheless, many of the VRAM concepts of
internal, on-chip buffering and organization have been used and improved in
modern graphics adapters.

 

A quick search for "dual port RAM" on Digikey coughs up https://www.idt.com/document/dst/713040-datasheet which is 1k * 8 in 48 pin DIP.

1kB is not much, but 48 pins is almost a breadboard full.

https://www.digikey.com/products/en/integrated-circuits-ics/memory/774?FV=ffe00306&quantity=0&ColumnSort=1000011&page=1&k=dual+port+ram&pageSize=25

 

What kind of size / capaicty / speed are you aiming for?

I've still got a drawer of 100 or so old 80486 cache static ram chips. Adding buffers to make it resemble a dual port ram seems more trouble than it's worth.

 

Idea:

Could you be interested in a Beaglebone Black?

This is a small Linux computer (800MHz or so) and it has 2 "PRU's" (Programmable Realtime Units). These are microcontrollers which run their own program (for real-time applications) completely separate from the main processor, and they also have shared memory with the main processor.

 

If you share some more info on the background problem you want to solve we may be able to come up with better suggestions.

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com