--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/C139-notes	Sun Oct 18 18:08:15 2020 +0000
@@ -0,0 +1,22 @@
+FC Tourmaline firmware differs from Magnetite in two principal ways when it
+comes to Mot C139 target support:
+
+* C139 LCD support is implemented in a more forward-looking manner: instead of
+  emulating TI's C-Sample at the lowest R2D driver level and therefore being
+  forever limited to 84x48 pixel display size, Tourmaline implements a new
+  96x64 pixel framebuffer, matching the native LCD size of C1xx phones.  The UI
+  configuration is still black&white only though - the Mother of FreeCalypso
+  has no current plans to support color UI on smaller LCD sizes than TI's
+  original 176x220 pix.
+
+* Our aftermarket FFS configuration has been changed from 64x3 at 0x3C0000 to
+  64x7 at 0x300000.  Our earlier 64x3 config was chosen back in 2015, at that
+  time we didn't know how much room we would end up needing for the firmware
+  image vs. how much FFS content we would eventually have, and this 64x3 config
+  is now deemed to be too small, allowing only one 64 KiB sector for FFS
+  content.  Our new FC Tourmaline aftermarket FFS config supports up to 320 KiB
+  of FFS content, matches what we use on other platforms with 4 MiB flash chips,
+  leaves 3 MiB for the firmware image (our current smallbw UI fw is only 2 MiB),
+  and still avoids intersection with Motorola's (or rather Compal's) original
+  FFS, which is important for avoiding problems in converting C139 phones back
+  and forth between Motorola and FreeCalypso firmwares.