Repository Cleanup

.editorconfig

@@ -0,0 +1,11 @@
+
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.{hpp,cpp,ini,md}]
+indent_style = tab
+indent_size = 4
+charset = utf-8

.gitignore

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+.pio
+.vscode

Include/ROM.hpp

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+#ifndef Header_ROM
+#define Header_ROM
+
+#include <Arduino.h>
+
+
+const uint8_t rom [] PROGMEM = {
+
+    0xd8 , 0x58 , 0xa0 , 0x7f , 0x8c , 0x12 , 0xd0 , 
+    0xa9 , 0xa7 , 0x8d , 0x11 , 0xd0 , 0x8d , 0x13 , 
+    0xd0 , 0xc9 , 0xdf , 0xf0 , 0x13 , 0xc9 , 0x9b , 
+    0xf0 , 0x3  , 0xc8 , 0x10 , 0xf  , 0xa9 , 0xdc , 
+    0x20 , 0xef , 0xff , 0xa9 , 0x8d , 0x20 , 0xef , 
+    0xff , 0xa0 , 0x1  , 0x88 , 0x30 , 0xf6 , 0xad , 
+    0x11 , 0xd0 , 0x10 , 0xfb , 0xad , 0x10 , 0xd0 , 
+    0x99 , 0x0  , 0x2  , 0x20 , 0xef , 0xff , 0xc9 , 
+    0x8d , 0xd0 , 0xd4 , 0xa0 , 0xff , 0xa9 , 0x0  , 
+    0xaa , 0xa  , 0x85 , 0x2b , 0xc8 , 0xb9 , 0x0  , 
+    0x2  , 0xc9 , 0x8d , 0xf0 , 0xd4 , 0xc9 , 0xae , 
+    0x90 , 0xf4 , 0xf0 , 0xf0 , 0xc9 , 0xba , 0xf0 , 
+    0xeb , 0xc9 , 0xd2 , 0xf0 , 0x3b , 0x86 , 0x28 , 
+    0x86 , 0x29 , 0x84 , 0x2a , 0xb9 , 0x0  , 0x2  , 
+    0x49 , 0xb0 , 0xc9 , 0xa  , 0x90 , 0x6  , 0x69 , 
+    0x88 , 0xc9 , 0xfa , 0x90 , 0x11 , 0xa  , 0xa  , 
+    0xa  , 0xa  , 0xa2 , 0x4  , 0xa  , 0x26 , 0x28 , 
+    0x26 , 0x29 , 0xca , 0xd0 , 0xf8 , 0xc8 , 0xd0 , 
+    0xe0 , 0xc4 , 0x2a , 0xf0 , 0x97 , 0x24 , 0x2b , 
+    0x50 , 0x10 , 0xa5 , 0x28 , 0x81 , 0x26 , 0xe6 , 
+    0x26 , 0xd0 , 0xb5 , 0xe6 , 0x27 , 0x4c , 0x44 , 
+    0xff , 0x6c , 0x24 , 0x0  , 0x30 , 0x2b , 0xa2 , 
+    0x2  , 0xb5 , 0x27 , 0x95 , 0x25 , 0x95 , 0x23 , 
+    0xca , 0xd0 , 0xf7 , 0xd0 , 0x14 , 0xa9 , 0x8d ,  
+    0x20 , 0xef , 0xff , 0xa5 , 0x25 , 0x20 , 0xdc , 
+    0xff , 0xa5 , 0x24 , 0x20 , 0xdc , 0xff , 0xa9 , 
+    0xba , 0x20 , 0xef , 0xff , 0xa9 , 0xa0 , 0x20 , 
+    0xef , 0xff , 0xa1 , 0x24 , 0x20 , 0xdc , 0xff , 
+    0x86 , 0x2b , 0xa5 , 0x24 , 0xc5 , 0x28 , 0xa5 , 
+    0x25 , 0xe5 , 0x29 , 0xb0 , 0xc1 , 0xe6 , 0x24 , 
+    0xd0 , 0x2  , 0xe6 , 0x25 , 0xa5 , 0x24 , 0x29 , 
+    0x7  , 0x10 , 0xc8 , 0x48 , 0x4a , 0x4a , 0x4a , 
+    0x4a , 0x20 , 0xe5 , 0xff , 0x68 , 0x29 , 0xf  , 
+    0x9  , 0xb0 , 0xc9 , 0xba , 0x90 , 0x2  , 0x69 , 
+    0x6  , 0x2c , 0x12 , 0xd0 , 0x30 , 0xfb , 0x8d , 
+    0x12 , 0xd0 , 0x60 , 0x0  , 0x0  , 0x0  , 0xf  , 
+    0x0  , 0xff , 0x0  , 0x0
+
+};
+
+
+#endif

Include/Settings.hpp

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+#ifndef Header_Settings
+#define Header_Settings
+
+
+// 2400 for the authentic experience, 9600 for something more enjoyable
+
+#define BAUD 2400
+#define CLOCK 53
+#define RESET 52
+#define RW 51
+
+
+#endif

README.md

@@ -1,35 +1,35 @@
-# Mega6502
-
-Mega6502 is an experiment implementing a minimal 8 bit platform using an Arduino and a 6502.
-
-# Hardware
-
-Mega6502 requires an Ardunio Mega 2560 development board and CMOS 65c02. The 65c02 should be connected to the Arduino as follows
-
-
-		  5v      GND                                 5v   Arduino 
-		  |        |       +------\/------+           |
-		  |        +----  1| Vss     /RES |40 -- 3k3 -+--- 52
-		  +--- 3k3 -----  2| RDY       ϕ2 |39  
-		  |               3| ϕ1       /SO |38  
-		  +--- 3k3 -----  4| IRQ       ϕ0 |37 -------- 53
-		  |               5| NC        NC |36  
-		  +--- 3k3 -----  6| /NMI      NC |35  
-		  |               7| SYNC     R/W |34 -------- 51
-		  +-------------  8| Vcc       D0 |33 -------- 49
-		    22 ---------  9| A0        D1 |32 -------- 48 
-		    23 --------- 10| A1        D2 |31 -------- 47
-		    24 --------- 11| A2        D3 |30 -------- 46
-		    25 --------- 12| A3        D4 |29 -------- 45
-		    26 --------- 13| A4        D5 |28 -------- 44
-		    27 --------- 14| A5        D6 |27 -------- 43
-		    28 --------- 15| A6        D7 |26 -------- 42
-		    29 --------- 16| A7       A15 |25 -------- 30
-		    37 --------- 17| A8       A14 |24 -------- 31
-		    36 --------- 18| A9       A13 |23 -------- 32
-		    35 --------- 19| A10      A12 |22 -------- 33
-		    34 --------- 20| A11      Vss |21 ---+
-		                   +--------------+      |
-		                                        GND
+# Mega6502 [![Badge License]][License]
 
+*An experimental implementation of a minimal* <br>
+*8 - bit platform using an **Arduino** + **6502** chip.*
 
+<br>
+
+## Hardware
+
+The **Mega6502** requires:
+
+ **1 x** `Ardunio Mega 2560` development board 
+
+ **1 x** `CMOS 65c02`
+
+<br>
+
+### Connections
+
+The **65c02** should be connected to the **Arduino** as follows:
+
+<br>
+
+<div align = center>
+
+<img src = 'Resources/Connections.svg' width = 420>
+
+</div>
+
+
+<!----------------------------------------------------------------------------->
+
+[Badge License]: https://img.shields.io/badge/License-MIT-yellow.svg?style=for-the-badge
+
+[License]: LICENSE

Source/Mega6502.cpp

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+
+#include "Settings.hpp"
+#include "EROM.hpp"
+#include "FROM.hpp"
+#include "ROM.hpp"
+
+#include <util/setbaud.h>
+#include <avr/pgmspace.h>
+#include <Arduino.h>
+
+
+#ifndef cbi
+#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+#endif
+
+#ifndef sbi
+#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+#endif
+
+#define ADDR ((addrh << 8) | addrl)
+
+byte ram[0x1000];
+byte pia[0x14];
+
+
+static uint8_t memRead(){
+
+	const uint8_t 
+		addrh = PINC,
+		addrl = PINA;
+
+	const uint16_t addr = ADDR;
+
+	uint8_t val;
+
+	switch(addr >> 12){
+	default:
+		// nothing in the address space, just return zero.
+		return 0x00;
+	case 0x0:
+		val = ram[addr];
+		return val;
+	case 0xd:
+
+		// fake 6821
+
+		switch(addrl){
+		case 0x10:
+			val = 0x80 | UDR0; 
+			break;
+		case 0x11:
+			val = UCSR0A & _BV(RXC0);
+			break;
+		case 0x12:
+			val = UCSR0A & _BV(UDRE0) ? 0x00 : 0xFF;
+			break;
+		default:
+			printf("pia: invalid read at %04x\n",addr);
+			val = 0;
+		break;
+		}
+
+		return val;
+	case 0xe:
+		val = pgm_read_byte(erom + (addr & 0x0fff));
+		return val;
+	case 0xf:
+		val = pgm_read_byte(from + (addr & 0x0fff));
+		return val;
+	}
+}
+
+
+static void memWrite(){
+
+    const uint8_t 
+		addrh = PINC,
+    	addrl = PINA,
+    	val = PINL;
+
+    const uint16_t addr = ADDR;
+
+    switch(addr >> 12){
+    default:
+        // nothing in the address space ignore the write;
+    	break;
+    case 0x0:
+        ram[addr] = val;
+    	break;
+    case 0xd:
+
+		switch(addrl){
+		default:
+			printf("pia: invalid write at %04x: %02x\n",addr,val);
+		break;
+		case 0x12:
+			putchar(val & 0x7f);
+		break;
+		case 0x11:
+			// ignore write to $D011, PIA is not configurable.
+			break;
+		case 0x13:
+			// ignore write to $D013, PIA is not configurable.
+			break;
+		}
+
+    	break;
+    }
+}
+
+int uart_putchar(char c,FILE * stream){
+
+    if(c == '\r')
+        uart_putchar('\n',stream);
+
+    loop_until_bit_is_set(UCSR0A,UDRE0);
+    UDR0 = c;
+
+    return 1;
+}
+
+static FILE uartout = {0} ;
+
+void uart_init(){
+
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+
+    #if USE_2X
+        UCSR0A |= _BV(U2X0);
+    #else
+        UCSR0A &= ~(_BV(U2X0));
+    #endif
+
+	// 8-bit data
+
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
+
+	// Enable RX and TX
+
+	UCSR0B = _BV(RXEN0) | _BV(TXEN0);
+
+    fdev_setup_stream(& uartout,uart_putchar,NULL,_FDEV_SETUP_WRITE);
+
+	stdout = & uartout;
+}
+
+
+void setup(){
+
+    uart_init();
+
+    printf("RESET\n");
+
+    pinMode(CLOCK, OUTPUT);
+    pinMode(RESET, OUTPUT);
+    pinMode(RW, INPUT);
+
+    digitalWrite(RESET, HIGH);
+
+    // setup PORTC to read the low byte of the address
+
+    DDRC = 0x00;
+    PORTC = 0x00;
+
+    // setup PORTA to do the same for the high byte
+
+    DDRA = 0x00;
+    PORTA = 0x00;
+
+    // send reset pulse
+
+    digitalWrite(RESET,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(CLOCK,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(CLOCK,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(CLOCK,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(CLOCK,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(CLOCK,LOW);
+    digitalWrite(CLOCK,HIGH);
+    digitalWrite(RESET,HIGH);
+}
+
+void loop(){
+
+    while(true){
+
+        cli();
+        cbi(PORTB,0);
+
+		// 4 * 62.5ns delay @ 16mhz
+
+        __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t"); 
+
+        sbi(PORTB, 0);
+        sei();
+
+        if(PINB & _BV(PB2)){
+
+            // read cycle
+
+            DDRL = 0xff;
+            PORTL = memRead();
+
+        } else {
+
+            // write cycle
+
+			DDRL = 0x00;
+            PORTL = 0;
+            memWrite();
+
+        }
+    }
+}