hmm... Im trying to remember. it's been a while.
The 19 and 8 are values that can be found in the source code.
damned if I can remember what they were.
19 was mode selection perhaps in this context and 8 was the "inversion" special type, but don't hold me to that...
https://wiki.mobileread.com/wiki/Framebuffer_for_Kindle for other values.
IIRC it had something to do with the command version and waveform versions availble on each revision of device
on the k3
_EINK_UPDATE_DISPLAY_WHICH=18
_FX_UPDATE_PART=0
_FX_UPDATE_FULL=1
_FX_UPDATE_FAST=2
_FX_UPDATE_SLOW=3 - full refresh with "flash"
_FX_BUFFER_LOAD=99
_FX_DISPLAY_PART=100
_FX_DISPLAY_FULL=101
on the DX:
_FX_UPDATE_PART=0
_FX_UPDATE_FULL=1
_EINK_UPDATE_DISPLAY_PART=1
_EINK_UPDATE_DISPLAY_FULL=2
_EINK_UPDATE_DISPLAY_AREA=3
_EINK_UPDATE_DISPLAY_FX=7
see also
https://www.mobileread.com/forums/sho...d.php?t=142848
and
http://pastebin.com/tzFsFWrg for k3 like examples
Hope that helps somewhat