Check out the usage possibility of serial SPI Flash parts. For example check out this part from Macronix which can be clocked at rates up to 86MHz. You would connect this to your MCU or CPLD logic on an SPI bus and then send the appropriate commands to it to put it into read mode. Once in read mode the device supports reading the entire chip in sequential mode. Using a programmable MCU SPI interface offers a convenient way for getting the device loaded up in the first place. Since its Flash it erases at the chip or sector level and programs at the page level. The device I pointed to is one of the latest in this product arena which support a lot of nice features including multiple erase block sizes and one and two bit wide read out modes.

The data sheet describes the reading process like this: The read command and address (three bytes) are latched on the rising edge of the SCLK and the data shifts out on the falling edge of the SCLK at a maximum frequency fR. The first address can be at any location. The address is automatically increased to the next higher address after each byte is shifted out so the whole memory can be read out at a single READ instruction. The address counter rolls over to 0 when the highest address has been reached. Reading is terminated when CS# eventially rises to a high level.

This part is real and is being used in several products I am working on right now. High volume costing is a couple of bucks or so. The vendors of these types of parts make various sizes available. Common packaging is the 300-mil SO16. The company I work for has enabled a socket for this style of package in the industry. I'll try to dig up info on the socket and see if it is commercially available.

Michael Karas