September 1999, Issue 110

Get Smart Media—(Part 1):
What's It All About?

FILL'N IT UP

I don’t know about yours, but my concept of erasing something is getting rid of everything. With memory devices, however, erasing is filling each memory cell with 1’s.

This is more like charging than it is erasing memory. And when it comes to programming, you need only worry about cells that need to be 0. Merely poke a hole in the bottom of each appropriate cell and let the unwanted 1 drain out.

Since a block (16k) is the smallest portion of the SmartMedia that can be erased at one time, only addresses A14–Axx are needed. Following the command byte 60H, only two address bytes (or three for SmartMedia greater than 32 MB) need to be passed.

But erasing will not commence automatically unless the command 0D0H follows the previous command and address bytes, which prevents unintentional erases. You can read the status to determine when the erasure has completed and whether or not any erasure errors were discovered.

Writing to the SmartMedia is similar to erasing a block. Writing, however, is handled on a page basis. Like reading, you may start anywhere within the page. The pointer is A0–A7 (the first address byte) with the A8 bit being the least significant bit of the command, in this case 80H (or 81H).

Following the rest of the address, A9–Axx (which selects the page and block), there is an "are you sure" command necessary as with erasing. This command byte, 10H, begins the page programming process. And, as with erasing, you can read the status to determine when the programming has completed and whether or not any program errors were discovered.