There are both modes available. Memory mapped one has lower resolution due to high memory requirements. Default full size one is unbuffered - data is transferred to LCD when drawing however it is not over SPI, there is 8bit parallel bus. See https://banglejs.com/reference#l_Bangle_setLCDMode
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
There are both modes available. Memory mapped one has lower resolution due to high memory requirements. Default full size one is unbuffered - data is transferred to LCD when drawing however it is not over SPI, there is 8bit parallel bus. See https://banglejs.com/reference#l_Bangle_setLCDMode