diff --git a/dbg.c b/dbg.c
new file mode 100644
index 0000000..bdc2b31
--- /dev/null
+++ b/dbg.c
@@ -0,0 +1,52 @@
+#include "dbg.h"
+#include "cpu.h"
+
+#include <readline/readline.h>
+#include <readline/history.h>
+#include <string.h>
+#include <stdlib.h>
+
+void debug(cpu_t *cpu)
+{
+	while (true)
+	{
+		char *input = readline("\033[33m> \033[0m");
+		if (!input)
+			continue;
+
+		char *tok = strtok(input, " \t\r\n\v");
+		
+		if (!strcmp(tok, "step") || !strcmp(tok, "s"))
+		{
+			step(cpu);
+		}
+		else if (!strcmp(tok, "show") || !strcmp(tok, "print"))
+		{
+			if ((tok = strtok(NULL, " ")))
+			{
+				char *ok = 0;
+				if (tok[0] == '$')
+				{
+					uint16_t addr = strtol(tok + 1, &ok, 16);
+
+					if (ok == 0)
+					{
+						printf("Memory:\n");
+						printf("\t$%x	%x\n", addr, cpu->mem[addr]);
+						printf("\t$%x	%x\n", addr + 1, cpu->mem[addr + 1]);
+					}
+				}
+				else
+				{
+					printf("Registers:\n");
+
+					#define R(r) printf("\t" #r ":	%x\n", cpu->regs[r]);
+						REGISTERS
+					#undef R
+				}
+			}
+		}
+
+		add_history(input);
+	}
+}