Bari Ari wrote:
A flash adapter of this type is only economical is high volume. The BOM and assembly costs in low volumes are higher than the cost of a off the shelf motherboard unless you plan on building them yourself and your time is of no or little value.
A design to page out flash memory into a small space in memory is done the way Expanded Memory was done for the old IBM-PC via page frames.
Here's an example of how it could map into system memory:
PC MAIN MEMORY LIM EXPANDED MEMORY -------------- -------------------
+-------------+ | | . Extended . . Memory . . up to . /+-------------+ 32M . 16M on the . // | | . '286, . / / | | . 4096M on . / / | Expanded | . the '386 . / / | Memory | | | / / | | 1M +-------------+ / / | Divided | | | / / | into 16K | 960K +-------------+ / | logical | | Page Frame | / | pages | | 12*16K | / | | | Physical | / | | | Pages | / | | 768K +-------------+\ / . . | | / . . 640K +-------------+/ \ . . | Page Frame | \ . . | 24*16K | \ | | | Physical | \ | | | Pages | \ | | | | \ | | 256K +-------------+ \ | | | | \ \ | | | | \ \ | | | | \ \ | | 0 +-------------+ \ \ | | \ \ | | \ \ | | \ | | +-------------+ 0
Sorry, the ascii drawing didn't format right, so here's a link for a drawing and an article on expanded memory:
http://www.eeng.brad.ac.uk/help/.dos/.expextmem.html
Bari