gernb1.....Igloo

This article got my attention, note the following paragraphs..

http://www.fpgajournal.com/articles_2006/20060829_igloo.htm

"When talking about the power consumption characteristics of flash-based FPGAs, it is important to recognize that there are two significantly different programmable logic architectures that are labeled "flash FPGA." Actel's flash-based FPGAs use non-volatile flash for the actual configuration logic such as routing. Other "flash" FPGAs are actually more of a hybrid architecture: the configuration logic itself is volatile (SRAM-based), but the configuration data is stored on-chip in a flash memory. In those devices, the configuration is quickly loaded into the SRAM elements from the on-chip flash at startup.

When examining most properties of the flash-based FPGA (single chip operation, apparently non-volatile behavior, etc.), these two architectures appear almost identical. When discussing power consumption, however, there is an important difference. Actel's approach has a distinct advantage in power consumption because the hybrid devices still require the volatile SRAM-based logic to be maintained with power just to keep the configuration active. Using Actel's approach, the configuration is still active, even with power removed from the device. That means that there is no power spike each time the device configures itself and no constant drain of current to keep the configuration active."

 IMO...they're doing exactly what e.Digital does. The statement of " more of a hybrid architecture" for the SRAM based method  miss leading.  The description is correct,  however,  it's not a hybrid other than utilizing SRAM instead of SDRAM.  IN any case no matter what RAM is utilized....it's a shadowing process from the flash normally utilizing SDRAM because of the expense of SRAM. There's a big difference and it depends on the size of the multiple pages to be shadowed. If you read further of the article you will understand.

Now comes "Using Actel's approach, the configuration is still active, even with power removed from the device."

The flash is NAND....so it needs a mechanism to move the data that is normally shadowed, If it was NOR flash you would not.

How are they doing it? IMO, they are copying e.Digitals high speed cache method...and creating a main memory out of a flash. Which utilizes a tiny SRAM...sized to one read/write block of the flash. NO shadowing. A stream is pushed  straight through it. This gives the effect that the flash is a main memory unit.

gernb1- keep at it
doni