From 5e42e2a80c1bf691bdfa229f1d95659dcd042662 Mon Sep 17 00:00:00 2001
From: Paul Warren <pwarren@pwarren.id.au>
Date: Mon, 16 Dec 2019 19:44:22 +1100
Subject: [PATCH] Bits from Ben

---
 6502-monitor.ino | 45 +++++++++++++++++++++++++++++++++++++++++++++
 makerom.py       | 24 ++++++++++++++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 6502-monitor.ino
 create mode 100644 makerom.py

diff --git a/6502-monitor.ino b/6502-monitor.ino
new file mode 100644
index 0000000..8f147cb
--- /dev/null
+++ b/6502-monitor.ino
@@ -0,0 +1,45 @@
+const char ADDR[] = {22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52};
+const char DATA[] = {39, 41, 43, 45, 47, 49, 51, 53};
+#define CLOCK 2
+#define READ_WRITE 3
+
+void setup() {
+  for (int n = 0; n < 16; n += 1) {
+    pinMode(ADDR[n], INPUT);
+  }
+  for (int n = 0; n < 8; n += 1) {
+    pinMode(DATA[n], INPUT);
+  }
+  pinMode(CLOCK, INPUT);
+  pinMode(READ_WRITE, INPUT);
+
+  attachInterrupt(digitalPinToInterrupt(CLOCK), onClock, RISING);
+  
+  Serial.begin(57600);
+}
+
+void onClock() {
+  char output[15];
+
+  unsigned int address = 0;
+  for (int n = 0; n < 16; n += 1) {
+    int bit = digitalRead(ADDR[n]) ? 1 : 0;
+    Serial.print(bit);
+    address = (address << 1) + bit;
+  }
+  
+  Serial.print("   ");
+  
+  unsigned int data = 0;
+  for (int n = 0; n < 8; n += 1) {
+    int bit = digitalRead(DATA[n]) ? 1 : 0;
+    Serial.print(bit);
+    data = (data << 1) + bit;
+  }
+
+  sprintf(output, "   %04x  %c %02x", address, digitalRead(READ_WRITE) ? 'r' : 'W', data);
+  Serial.println(output);  
+}
+
+void loop() {
+}
diff --git a/makerom.py b/makerom.py
new file mode 100644
index 0000000..c8ad430
--- /dev/null
+++ b/makerom.py
@@ -0,0 +1,24 @@
+#
+# Please see this video for details:
+# https://www.youtube.com/watch?v=yl8vPW5hydQ
+#
+code = bytearray([
+  0xa9, 0xff,         # lda #$ff
+  0x8d, 0x02, 0x60,   # sta $6002
+
+  0xa9, 0x55,         # lda #$55
+  0x8d, 0x00, 0x60,   # sta $6000
+
+  0xa9, 0xaa,         # lda #$aa
+  0x8d, 0x00, 0x60,   # sta $6000
+
+  0x4c, 0x05, 0x80,   # jmp $8005
+  ])
+
+rom = code + bytearray([0xea] * (32768 - len(code)))
+
+rom[0x7ffc] = 0x00
+rom[0x7ffd] = 0x80
+
+with open("rom.bin", "wb") as out_file:
+  out_file.write(rom)