added apple1basic

Author: mist64

Makefile.apple1basic

@@ -0,0 +1,12 @@
+OBJS=perfect6502.o apple1basic.o 
+CFLAGS=-Werror -Wall -O3
+CC=clang
+
+all: apple1basic
+
+apple1basic: $(OBJS)
+	$(CC) -o apple1basic $(OBJS)
+
+clean:
+	rm -f $(OBJS) apple1basic
+

apple1basic.bin

@@ -0,0 +1,131 @@
+#include <stdio.h>
+#ifndef _WIN32
+#include <sys/stat.h>
+
+#include "perfect6502.h"
+ 
+/************************************************************
+ *
+ * Interface to OS Library Code / Monitor
+ *
+ ************************************************************/
+
+/* imported by runtime.c */
+unsigned char A, X, Y, S, P;
+unsigned short PC;
+int N, Z, C;
+
+void
+init_monitor()
+{
+	FILE *f;
+	f = fopen("apple1basic.bin", "r");
+	fread(memory + 0xE000, 1, 4096, f);
+	fclose(f);
+
+	memory[0xfffc] = 0x00;
+	memory[0xfffd] = 0xE0;
+
+}
+
+
+void
+charout(char ch) {
+	unsigned short S = readSP();
+	unsigned char a = 1 + memory[0x0100+S+1] | memory[0x0100+((S+2) & 0xFF)] << 8;
+
+	/*
+	 * Apple I BASIC prints every character received
+	 * from the terminal. UNIX terminals do this
+	 * anyway, so we have to avoid printing every
+	 * line again
+	 */
+	if (a==0xe2a6)	/* character echo */
+		return;
+	if (a==0xe2b6)	/* CR echo */
+		return;
+
+	/*
+	 * Apple I BASIC prints a line break and 6 spaces
+	 * after every 37 characters. UNIX terminals do
+	 * line breaks themselves, so ignore these
+	 * characters
+	 */
+	if (a==0xe025 && (ch==10 || ch==' '))
+		return;
+
+	/* INPUT */
+	if (a==0xe182) {
+#if _WIN32
+		if (!isatty(0))
+			return;
+#else
+		struct stat st;
+		fstat(0, &st);
+		if (S_ISFIFO (st.st_mode))
+			return;
+#endif
+	}
+#endif
+
+	putc(ch, stdout);
+	fflush(stdout);
+}
+
+void
+handle_monitor()
+{
+	if (readRW()) {
+		unsigned short a = readAddressBus();
+		if ((a & 0xFF1F) == 0xD010) {
+			unsigned char c = getchar();
+			if (c == 10)
+				c = 13;
+			c |= 0x80;
+			writeDataBus(c);
+		}
+		if ((a & 0xFF1F) == 0xD011) {
+			if (readPC() == 0xE006)
+				/* if the code is reading a character, we have one ready */
+				writeDataBus(0x80);
+			else
+				/* if the code checks for a STOP condition, nothing is pressed */
+				writeDataBus(0);
+		}
+		if ((a & 0xFF1F) == 0xD012) {
+			/* 0x80 would mean we're not yet ready to receive a character */
+			writeDataBus(0);
+		}
+	} else {
+		unsigned short a = readAddressBus();
+		unsigned char d = readDataBus();
+		if ((a & 0xFF1F) == 0xD012) {
+			unsigned char temp8 = d & 0x7F;
+			if (temp8 == 13)
+				temp8 = 10;
+			charout(temp8);
+		}
+	}
+}
+
+int
+main()
+{
+	int clk = 0;
+
+	initAndResetChip();
+
+	/* set up memory for user program */
+	init_monitor();
+
+	/* emulate the 6502! */
+	for (;;) {
+		step();
+		clk = !clk;
+		if (!clk)
+			handle_monitor();
+
+//		chipStatus();
+		//if (!(cycle % 1000)) printf("%d\n", cycle);
+	};
+}

apple1basic.c

@@ -10,6 +10,7 @@ extern unsigned char readSP();
 extern unsigned char readP();
 extern unsigned int readRW();
 extern unsigned short readAddressBus();
+extern void writeDataBus(unsigned char);
 extern unsigned char readDataBus();
 extern unsigned char readIR();