Minor changes

1 files changed, 20 insertions, 0 deletions

diff --git a/src/vcpu.h b/src/vcpu.h
index 7eed76f..c85744d 100644
--- a/src/vcpu.h
+++ b/src/vcpu.h
@@ -1,6 +1,26 @@
 #pragma once
 
 typedef struct VCPU_State {
+  // Program Counter (16 bits but only 12 bits used (4096 memory addresses))
+  unsigned short PC;
+
+  // Index register (16 bits but only 12 bits used (4096 memory addresses))
+  unsigned short I;
+
+  // Stack register (16 bits)
+  unsigned short S;
+
+  // General purpose registers (8 bits each)
+  // Note last one often used as a flag register
+  unsigned char V[16];
+
+  // Delay timer (8 bits)
+  unsigned char DT;
+
+  // Sound timer (8 bits)
+  unsigned char ST;
+
+  // Intruction (opcode + decoded fields)
   short opcode;
   char X;
   char Y;