嵌入式（AVR / MSP微控制器）系统的闪存和SRAM的趋势

Question

I am wondering how the memory in deeply embedded systems such as avr/msp microcontroller (avr atmega128/TI msp430) would evolve. My hunch is that Flash memory is becoming smaller and cheaper at a much faster rate than SRAM. I am looking for cost per byte and size per byte of Flash memory used in avr/msp and internal SRAM to backup that claim. I googled quite a bit but couldn't find clear answer yet. Any pointers or data would be helpful. Thank you.

Answer 1

An older chip, but see these die shots of the AT90S8515:

http://www.flylogic.net/blog/?p=24

The article states the flash as 8KB, SRAM 512B.

By eye, the RAM area highlighted is about 25% the size of the flash area, so you might get 2KB in the same area. Hence (in that chip on that process) flash seems about 4x more dense than SRAM. And cost and area are very closely linked in silicon terms.

The reason there's more flash in a micro is not really related to cost though - you'll always get lots of flash relative to SRAM as that's where the application code lives! The two types of memory have very different characteristics and hence functions within an embedded system.