Restructure documentation

Move all extra documentation files into doc/ and move reverse
engineering related notes to a separate directory, to keep things tidy.

doc/reverse-engineering/stc12-options.txt

@@ -0,0 +1,70 @@
+Model-specific configuration registers
+Placement of configuration values
+
+"~" means the bit is a negated boolean. Sometimes values overlap,
+depending on MCU model.
+
+In STC10/11/12 series, the first 4 MCS bytes have active
+values. Generally, unused bits should be set to 1.
+
+
+MCS0
+----
+
+MSB     7       6       5       4       3       2       1       0       LSB
+                ~RS2LV  OSC1    OSC0                            RSPEN
+                ~LVD
+
+RSPEN := RESET pin enable
+~RS2LV := RESET2 pin low voltage detect enable
+~LVD   := low voltage detect enable
+OSC0, OSC1 := oscillator stabilization delay
+
+OSC1    OSC0    delay
+0       0       4096
+0       1       8192
+1       0       16384
+1       1       32768
+
+
+MCS1
+----
+
+MSB     7       6       5       4       3       2       1       0       LSB
+        ~PORD   OSCG                                    CLKSRC
+
+~PORD := power-on-reset (POR) delay (0 = long, 1 = short)
+OSCG := high oscillator gain
+CLKSRC := clock source (0 = internal RC, 1 = external crystal)
+
+
+MCS2
+----
+
+MSB     7       6       5       4       3       2       1       0       LSB
+                        ~WDEN           ~WDSTP  WDPS2   WDPS1   WDPS0
+
+~WDEN := watchdog enable after power-on-reset
+~WDSTP := stop watchdog counter in idle mode
+WDPS2...WDPS0 := watchdog counter prescaler
+
+WDPS2   WDPS1   WDPS0   divisior
+0       0       0       2 
+0       0       1       4
+0       1       0       8
+0       1       1       16
+1       0       0       32
+1       0       1       64
+1       1       0       128
+1       1       1       256
+
+
+MCS3
+----
+
+MSB     7       6       5       4       3       2       1       0       LSB
+                                                        ~EREE   ~BSLD
+
+~EREE := enable eeprom erase next time MCU is programmed
+~BSLD := enable BSL pin detect; i.e. BSL is only enabled if P1.0/P1.1
+         (or others, depends on MCU model) are held low on POR.