Add some details

README.txt

@@ -1,15 +1,37 @@
-#Apple 1 Replica
+#Apple 1 REPLICA
 
+Raw but full working implementation of Apple 1 replica, based on real W6502C MPU (modern 6502) and Arduino Due 4KB+4KB RAM.
+
+Arduino Due just listen and write/write the 6502 pins (RW/Address/Data Bus), emulate the PIA (6821) Keyboard & Display + handle the 6502 clock.
+
+The project was originally implemented on an Arduino UNO that is in any case limited in terms of RAM and also less performant. Arduino Due is a perfect fit instead.
+
+The project is build over platform.io but you should be able to compile it in the Arduino standard IDE too, without any change.
+
+## Serial client recommended settings (I'm using Serial under OSX):
+- BAUD RATE: 115200
+- Data Bits: 8
+- Parity: None
+- Stop Bits: 1
+- Flow Control: (everything OFF)
+- Emulation XTerm
+- Send Mode: Immediate
+- Return Key: CR
+- Delete Key: DEL
+- Text Pacing: Normal
+- Uppercase Typed Characters: ON
+
+## 6502 to Arduino Pin schema:
 
                         W65C02S <->  Arduino Due
 
-        3.3v      GND                                 3.3v
-         |        |       +------\/------+           |
-         |        +----  1| VPB     /RES |40 -- 3k3 -+--- RST BTN
+        3.3v      GND                          10uf ---- GND
+         |        |       +------\/------+      |
+         |        +----  1| VPB     /RES |40 ---+------- +RST BTN- ---- GND
          +--- 3k3 -----  2| RDY    PHI2O |39
          |               3| PHI1O    SOB |38
          +--- 3k3 -----  4| IRQ     PHI2 |37 -------- 52
-         |               5| MLB       BE |36---3k3----3.3v
+         |               5| MLB       BE |36---3k3--------3.3v
          +--- 3k3 -----  6| /NMI      NC |35
          |               7| SYNC     R/W |34 -------- 53
          +-------------  8| VDD       D0 |33 -------- 30
@@ -27,3 +49,35 @@
            11 --------- 20| A11      VSS |21 ---+
                           +--------------+      |
                                                GND
+
+    Note: You may want to put a 100Uf capacitor near the 3.3v & GND lines too.
+
+## Auto loaded Program & extended Memory
+The Arduino sketch (main.cpp) automatically load the original Apple 1 Basic in the extended RAM at E000 address (was loaded via Tape in the original version).
+
+Same is done with a Program included in AUTLOAD variable (look into programs.h).
+You can comment & uncomment other programs as needed to get them auto loaded in the related RAM location.
+First word in the source is the location in RAM when the program should be loaded. This is not part of any original logic, it's just a convenient way to fast load programs without manually inserting them via Woz Monitor.
+
+You can easily comment out this logic or extend it as needed.
+
+## MASM version of WAZ MONITOR (Official Apple 1 ROM)
+Inside ASM folder you can find the woz_monitor_masm.asm source listing. This is the original ROM listing found in the apple 1 manual converted to be compatible with masm.
+
+If you are under OSX - you can install MASM via homebrew and use it to compile any asm source included the one above.
+
+## Apple 1 Address space
+$0000-$0FFF ------------- 4KB RAM
+   $0024-$002B ---------- WOZ MONITOR STORE (better to not overwrite)
+   $0200-$027F ---------- INPUT BUFFER (as the one above)
+$D010-$D013 ------------- PIA (6821) [KBD & DSP]
+$E000-$EFFF ------------- 4KB extended RAM (Usually for BASIC prog)
+$FF00-$FFFF ------------- 256 Bytes ROM (crazy! with just 2 bytes unused.)
+
+
+## Resources
+- http://dave.cheney.net/2014/12/26/make-your-own-apple-1-replica (I used this as a base reference)
+- https://coronax.wordpress.com/projects/project65/ (Good to understand by steps how a 6502 works)
+- http://archive.computerhistory.org/resources/text/Apple/Apple.AppleI.1976.102646518.pdf (apple 1 official manual)
+- https://en.wikipedia.org/wiki/WDC_65C02
+- http://www.westerndesigncenter.com/wdc/w65c21-chip.cfm

src/main.cpp

@@ -8,7 +8,7 @@ const int SERIAL_SPEED = 115200; // Arduino Serial Speed
 
 const int CLOCK_PIN   = 52; // TO 6502 CLOCK
 const int RW_PIN      = 53; // TO 6502 R/W
-const int CLOCK_DELAY = 3;  // HIGH / LOW CLOCK STATE DELAY
+const int CLOCK_DELAY = 3;  // HIGH / LOW CLOCK STATE DELAY (You can slow down it as much as you want)
 
 const char SERIAL_BS = 0x08;