add some thoughts about clock

notes

@@ -1,10 +1,53 @@
+per-scanline modes
+    Actual Apple II TEXT/GR and HGR video address patterns are in Understanding the Apple II
+        Not for DHGR or 80-col but they're probably just same address twice alternating banks
+    tracking clock and reporting video memory contents
+        clock
+            actual fastest clock is 14.31818MHz
+            one tick of ~1MHz clock maps to one tick of address counter
+                so is 7 HGR bits or one GR/TEXT horizontal cell
+            unsigned long would overflow after 20 minutes
+            But could modulo byteclock by 14318180 at interface update
+              time and not overflow
+                as long as it doesn't take longer than 20 minutes between calls to APPLE2Einterface::iterate
+                than 20 minutes...)
+            Want current CPU clock count after "cycle()" - map that to 14MHz clocks, can map that to actual wall clock
+            "most 6502 cycles are 978 nS long [14 14mhz clocks], but every 65th cycle is 1117 nS long [16 14mhz clocks]."
+            So wall clock time is (((clockcount / 65) * 912 + clockcount * 16) / 14318180 seconds) but only starting from 0
+                so need seconds from t_phase to t_clocks in clock counts where t_phase != 0
+                initially t_phase = 0
+                t_elapsed_14mhz = t_clocks * 14 + (t_clocks + t_phase) / 65 * 16
+                t = t + t_elapsed_14mhz / 14318180
+                t_phase = (t_phase + t_clocks) % 65
+            So clk would remain machine clock cycles, but actual wall clock time won't be known until calculated
+                Could increment wall clock at clk++ depending on phase, but then probably accumulate error because 14MHz clock rate is so high
+            Current CPU clk (in 1MHz CPU cycles) :
+                is used to determine to which audio sample (at libAO sample rate) in the audio waveform we should fill
+                    OK - should work with higher fixed rate
+                is used to mark after how many cycles the open apple key should be raised
+                    checked against clk in 
+                    HM - need to convert to wall clock?
+                    doesn't need to be that 
+        address generator
+            honor softswitches
+            convert byteclock to address
+        read empty memory address on bus no longer fails but instead
+            generate address, get byte from RAM and return it
+    recording softswitch mode changes
+        store vector of switch or mode change and byteclock
+        instead of setting before APPLE2Einterface::iterate, pass into iterate
+    honoring softswitch change in APPLE2Einterface
+        initialize scanline mode array to text
+        receive vector of tuple of byteclock and modes
+        fill scanline mode array from passed in vector
+        draw framebuffer by scanline
+
 final release:
     help screen
     gamepad calibration screen (for desktop GLFW anyway)
         need to handle asynchronous gamepad arrival (a la HTML5)
     screenshots for README.md
     link to emscripten version
-    Linux build
 
 emscripten:
     safari misses 'V' for some reason