Based on the present SDK, the available space that customers can use are as below.
RAM size <45kB (In station Mode, when connected to AP, the available space of heap+data is about 40+KB)
No programm rom in chip, user codes are strored in spi flash. Take 4Mbit spi flash as example,the current available program area is <64KB.
The maximum size of flash that ESP8266 support can be up to 128Mbit.
Thanks for your interest in ESP8266! 
Statistics: Posted by Espressif_Kelly — Fri Jan 09, 2015 7:07 pm
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