#13: Move cursor backward on ASCII Backspace

README.md

@@ -36,8 +36,8 @@ are always welcome.
 
 ## 3.0 Features
 
-Symon can simulate multiple 6502 based architectures. At present, three
-machines are implemented: Symon (the default), MULTICOMP, and a "Simple"
+Symon can simulate multiple 6502 based architectures. At present, four
+machines are implemented: Symon (the default), MULTICOMP, BenEater, and a "Simple"
 machine useful for debugging.
 
 ### 3.1 Memory Maps
@@ -64,6 +64,13 @@ memory.
 
   - `$0000`--`$FFFF`: 64KB RAM
 
+#### 3.1.4 BenEater Memory Map
+
+  - `$0000`--`$3FFF`: 16KB RAM
+  - `$5000`--`$5003`: MOS 6551 ACIA (Serial Console)
+  - `$6000`--`$600F`: 6522 VIA
+  - `$8000`--`$FFFF`: 16KB ROM
+
 ### 3.2 Serial Console and CPU Status
 
 ![Serial Console](https://github.com/sethm/symon/raw/master/screenshots/console.png)
@@ -218,6 +225,7 @@ to specify machine type and CPU type. The options are:
   - `-machine symon`: Use the **Symon** machine type by default.
   - `-machine multicomp`: Use the **Multicomp** machine type by default.
   - `-machine simple`: Use the **Simple** machine type by default.
+  - `-machine beneater`: Use the **BenEater** machine type by default.
   - `-rom <file>`: Use the specified file as the ROM image.
 
 ### 4.2 ROM images

src/main/java/com/loomcom/symon/Main.java

@@ -28,6 +28,7 @@ package com.loomcom.symon;
 import com.loomcom.symon.machines.MulticompMachine;
 import com.loomcom.symon.machines.SimpleMachine;
 import com.loomcom.symon.machines.SymonMachine;
+import com.loomcom.symon.machines.BenEaterMachine;
 import org.apache.commons.cli.*;
 
 import java.util.Locale;
@@ -72,6 +73,9 @@ public class Main {
                     case "symon":
                         machineClass = SymonMachine.class;
                         break;
+                    case "beneater":
+                        machineClass = BenEaterMachine.class;
+                        break;
                     default:
                         System.err.println("Could not start Symon. Unknown machine type " + machine);
                         return;
@@ -102,7 +106,7 @@ public class Main {
 
             while (true) {
                 if (machineClass == null) {
-                    Object[] possibilities = {"Symon", "Multicomp", "Simple"};
+                    Object[] possibilities = {"Symon", "Multicomp", "Simple", "BenEater"};
                     String s = (String)JOptionPane.showInputDialog(
                             null,
                             "Please choose the machine type to be emulated:",
@@ -117,6 +121,8 @@ public class Main {
                         machineClass = MulticompMachine.class;
                     } else if (s != null && s.equals("Simple")) {
                         machineClass = SimpleMachine.class;
+                    } else if (s != null && s.equals("BenEater")) {
+                        machineClass = BenEaterMachine.class;
                     } else {
                         machineClass = SymonMachine.class;
                     }

src/main/java/com/loomcom/symon/jterminal/vt100/Vt100TerminalModel.java

@@ -215,7 +215,8 @@ public class Vt100TerminalModel extends AbstractTerminalModel {
 				case '\t':
 					while ((++cursorColumn % TAB_WIDTH) != 0);
 					continue;
-				case 127:
+				case 8:   // ASCII Backspace
+				case 127: // ASCII Delete
 					if (cursorColumn > 0) {
 						cells[cursorRow][--cursorColumn] = null;
 					}

src/main/java/com/loomcom/symon/machines/BenEaterMachine.java

@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2016 Seth J. Morabito <web@loomcom.com>
+ *                    Maik Merten <maikmerten@googlemail.com>
+ *                    Chelsea Wilkinson <mail@chelseawilkinson.me>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package com.loomcom.symon.machines;
+
+import com.loomcom.symon.Bus;
+import com.loomcom.symon.Cpu;
+import com.loomcom.symon.devices.*;
+import com.loomcom.symon.exceptions.MemoryRangeException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+
+public class BenEaterMachine implements Machine {
+
+    private final static Logger logger = LoggerFactory.getLogger(BenEaterMachine.class.getName());
+
+    // Constants used by the simulated system. These define the memory map.
+    private static final int BUS_BOTTOM = 0x0000;
+    private static final int BUS_TOP    = 0xffff;
+
+    // 16K of RAM from $0000 - $3FFF
+    private static final int MEMORY_BASE = 0x0000;
+    private static final int MEMORY_SIZE = 0x4000;
+
+    // VIA at $6000-$600F
+    private static final int PIA_BASE = 0x6000;
+
+    // ACIA at $5000-$5003
+    private static final int ACIA_BASE = 0x5000;
+
+    // CRTC at $4000-$4001
+    private static final int CRTC_BASE = 0x4000;
+
+    // 32KB ROM at $8000-$FFFF
+    private static final int ROM_BASE = 0x8000;
+    private static final int ROM_SIZE = 0x8000;
+
+
+        // The simulated peripherals
+    private final Bus    bus;
+    private final Cpu    cpu;
+    private final Acia   acia;
+    private final Pia    pia;
+    private final Crtc   crtc;
+    private final Memory ram;
+    private       Memory rom;
+
+
+    public BenEaterMachine(String romFile) throws Exception {
+        this.bus = new Bus(BUS_BOTTOM, BUS_TOP);
+        this.cpu = new Cpu();
+        this.ram = new Memory(MEMORY_BASE, MEMORY_BASE + MEMORY_SIZE - 1, false);
+        this.pia = new Via6522(PIA_BASE);
+        this.acia = new Acia6551(ACIA_BASE);
+        this.crtc = new Crtc(CRTC_BASE, ram);
+
+        bus.addCpu(cpu);
+        bus.addDevice(ram);
+        bus.addDevice(pia);
+        bus.addDevice(acia);
+        bus.addDevice(crtc);
+
+        if (romFile != null) {
+            File romImage = new File(romFile);
+            if (romImage.canRead()) {
+                logger.info("Loading ROM image from file {}", romImage);
+                this.rom = Memory.makeROM(ROM_BASE, ROM_BASE + ROM_SIZE - 1, romImage);
+            } else {
+                logger.info("Default ROM file {} not found, loading empty R/W memory image.", romImage);
+                this.rom = Memory.makeRAM(ROM_BASE, ROM_BASE + ROM_SIZE - 1);
+            }
+        } else {
+            logger.info("No ROM file specified, loading empty R/W memory image.");
+            this.rom = Memory.makeRAM(ROM_BASE, ROM_BASE + ROM_SIZE - 1);
+        }
+
+        bus.addDevice(rom);
+
+    }
+
+    @Override
+    public Bus getBus() {
+        return bus;
+    }
+
+    @Override
+    public Cpu getCpu() {
+        return cpu;
+    }
+
+    @Override
+    public Memory getRam() {
+        return ram;
+    }
+
+    @Override
+    public Acia getAcia() {
+        return acia;
+    }
+
+    @Override
+    public Pia getPia() {
+        return pia;
+    }
+
+    @Override
+    public Crtc getCrtc() {
+        return crtc;
+    }
+
+    @Override
+    public Memory getRom() {
+        return rom;
+    }
+
+    public void setRom(Memory rom) throws MemoryRangeException {
+        if(this.rom != null) {
+            bus.removeDevice(this.rom);
+        }
+        this.rom = rom;
+        bus.addDevice(this.rom);
+    }
+
+    @Override
+    public int getRomBase() {
+        return ROM_BASE;
+    }
+
+    @Override
+    public int getRomSize() {
+        return ROM_SIZE;
+    }
+
+    @Override
+    public int getMemorySize() {
+        return MEMORY_SIZE;
+    }
+
+    @Override
+    public String getName() {
+        return "benEater";
+    }
+
+
+}