Clarify how to load ROMs in README files

Fixes #7.

.gitignore

@@ -1,4 +1,5 @@
 *~
+*.jar
 *#
 target
 .DS_Store

README.md

@@ -69,14 +69,29 @@ memory.
 ![Serial Console](https://github.com/sethm/symon/raw/master/screenshots/console.png)
 
 The main window of the simulator acts as the primary Input/Output
-system through a virtual serial terminal. The terminal is attached to
-a simulated ACIA, including a programmable baud rate generator that
-tries to approximate the correct "feel" of the programmed baud rate.
-(The sample Enhanced BASIC ROM image is programmed for 9600 baud)
+system through a virtual serial terminal. It also provides CPU status.
+Contents of the accumulator, index registers, processor status flags,
+disassembly of the instruction register, and stack pointer are all displayed.
 
-It also provides CPU status. Contents of the accumulator, index
-registers, processor status flags, disassembly of the instruction
-register, and stack pointer are all displayed.
+The terminal is attached to a simulated MOS 6551 ACIA. It behaves very much
+as described in the datasheet, with some exceptions:
+
+  - The simulated ACIA is permanently connected to the virtual terminal,
+    the Data Carrier Detect and Data Set Ready status bits always indicate
+    a connection is ready.
+  - The parity, stop-bits and bits-per-character settings are ignored. The
+    ACIA always sends and receives 8-bit characters, and parity errors
+    do not occur.
+  - The ACIA tries to honour the configured baud rate, but as a special case
+    the default "16x External Clock" rate is interpreted to mean "as fast as
+    possible" (The sample Enhanced BASIC ROM image is programmed for 9600 baud).
+  - The ACIA ignores the configured state of the Data Terminal Ready pin;
+    it is always ready to receive and transmit.
+
+For more information on the MOS 6551 ACIA and its programming model,
+see the official datasheet:
+
+  - [MOS 6551 ACIA](http://archive.6502.org/datasheets/mos_6551_acia.pdf)
 
 ![Font Selection](https://github.com/sethm/symon/raw/master/screenshots/font_selection.png)
 
@@ -212,10 +227,9 @@ properly. Without a ROM in memory, the simulator will not be able to
 reset, since the reset vector for the 6502 is located in the ROM
 address space.
 
-By default, any file named `rom.bin` that exists in the same directory
-where Symon is launched will be loaded as a ROM image. ROM images can
-also be swapped out at run-time with the "Load ROM Image..." in the
-File menu.
+ROM images can be loaded with the `-rom` argument when running
+Symon from the command line. ROM images can also be swapped out at
+run-time with the "Load ROM..." item in the File menu.
 
 The "samples" directory contains a ROM image for the Symon
 architecture named 'ehbasic.rom', containing Lee Davison's Enhanced

samples/README

@@ -11,7 +11,6 @@ Sample Programs
   When loaded at address $0300, this program will echo back to the console
   anything typed.
 
-
 Both hello.prg and echo_poll.prg were assembled with the Ophis assembler:
 
    https://hkn.eecs.berkeley.edu/~mcmartin/ophis/
@@ -19,23 +18,25 @@ Both hello.prg and echo_poll.prg were assembled with the Ophis assembler:
 3. echo_irq.rom
 
   This is another echo program, and behaves identically to echo_poll.prg,
-  except it is interrupt-driven.
+  except it is interrupt-driven. This ROM can be loaded either through the
+  "File->Load ROM..." menu in Symon, or by specifying the path to
+  "echo_irq.rom" with the "-jar" command line option when running Symon,
+  for example: `java -jar symon-1.3.2.jar -rom samples/echo_irq.rom`
 
 4. ehbasic.rom
 
    This is Lee Davison's Enhanced 6502 BASIC.
 
-   To use this ROM image, just copy the file 'ehbasic.rom' into the directory
-   where you run Symon. Rename the file to 'rom.bin'.  When you start Symon,
-   the ROM file will be automatically loaded at address $d000.
+   The EhBASIC ROM can be loaded either through the "File -> Load ROM..."
+   menu in Symon, or by specifying the path to "ehbasic.rom" with
+   the "-jar" command line option when running Symon, for example:
+   `java -jar symon-1.3.2.jar -rom samples/ehbasic.rom`
 
    Click the "Run" button and EhBASIC should automatically start running.
 
    Type 'C' to do a cold start.
 
-   Then, type $C000 when prompted for the memory size.
-
-   NOTE: EhBASIC only wants upper-case input. This confused me at first!
+   Then, type '49152' (without the quotes) when prompted for the memory size.
 
    More information can be found in the 'ehbasic' directory, and by visiting
    the EhBASIC web page:

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

@@ -126,7 +126,7 @@ public class Cpu implements InstructionTable {
         // Clear status register bits.
         state.carryFlag = false;
         state.zeroFlag = false;
-        state.irqDisableFlag = false;
+        state.irqDisableFlag = true;
         state.decimalModeFlag = false;
         state.breakFlag = false;
         state.overflowFlag = false;

src/main/java/com/loomcom/symon/devices/Acia6551.java

@@ -28,7 +28,7 @@ import com.loomcom.symon.exceptions.MemoryRangeException;
 
 /**
  * This is a simulation of the MOS 6551 ACIA, with limited
- * functionality.  Interrupts are not supported.
+ * functionality.
  * <p/>
  * Unlike a 16550 UART, the 6551 ACIA has only one-byte transmit and
  * receive buffers. It is the programmer's responsibility to check the
@@ -53,6 +53,14 @@ public class Acia6551 extends Acia {
 
     public Acia6551(int address) throws MemoryRangeException {
         super(address, ACIA_SIZE, "ACIA");
+
+        // Figure 6 in the 6551 ACIA data sheet says the "hardware reset"
+        // state of the Control Register is all zeros.
+        setControlRegister(0b00000000);
+        // Figure 7 of the 6551 ACIA data sheet says the "hardware reset"
+        // state of the Command Register is zeros, but Transmitter Control
+        // is set to "interrupt disabled, ready to send".
+        setCommandRegister(0b00000010);
     }
 
     @Override
@@ -74,16 +82,16 @@ public class Acia6551 extends Acia {
     @Override
     public void write(int address, int data) throws MemoryAccessException {
         switch (address) {
-            case 0:
+            case DATA_REG:
                 txWrite(data);
                 break;
-            case 1:
+            case STAT_REG:
                 reset();
                 break;
-            case 2:
+            case CMND_REG:
                 setCommandRegister(data);
                 break;
-            case 3:
+            case CTRL_REG:
                 setControlRegister(data);
                 break;
             default:
@@ -110,67 +118,60 @@ public class Acia6551 extends Acia {
         controlRegister = data;
         int rate = 0;
 
-        // If the value of the data is 0, this is a request to reset,
-        // otherwise it's a control update.
-
-        if (data == 0) {
-            reset();
-        } else {
-            // Mask the lower three bits to get the baud rate.
-            int baudSelector = data & 0x0f;
-            switch (baudSelector) {
-                case 0:
-                    rate = 0;
-                    break;
-                case 1:
-                    rate = 50;
-                    break;
-                case 2:
-                    rate = 75;
-                    break;
-                case 3:
-                    rate = 110; // Real rate is actually 109.92
-                    break;
-                case 4:
-                    rate = 135; // Real rate is actually 134.58
-                    break;
-                case 5:
-                    rate = 150;
-                    break;
-                case 6:
-                    rate = 300;
-                    break;
-                case 7:
-                    rate = 600;
-                    break;
-                case 8:
-                    rate = 1200;
-                    break;
-                case 9:
-                    rate = 1800;
-                    break;
-                case 10:
-                    rate = 2400;
-                    break;
-                case 11:
-                    rate = 3600;
-                    break;
-                case 12:
-                    rate = 4800;
-                    break;
-                case 13:
-                    rate = 7200;
-                    break;
-                case 14:
-                    rate = 9600;
-                    break;
-                case 15:
-                    rate = 19200;
-                    break;
-            }
-
-            setBaudRate(rate);
+        // Mask the lower four bits to get the baud rate.
+        int baudSelector = data & 0x0f;
+        switch (baudSelector) {
+            case 0:
+                rate = 0;
+                break;
+            case 1:
+                rate = 50;
+                break;
+            case 2:
+                rate = 75;
+                break;
+            case 3:
+                rate = 110; // Real rate is actually 109.92
+                break;
+            case 4:
+                rate = 135; // Real rate is actually 134.58
+                break;
+            case 5:
+                rate = 150;
+                break;
+            case 6:
+                rate = 300;
+                break;
+            case 7:
+                rate = 600;
+                break;
+            case 8:
+                rate = 1200;
+                break;
+            case 9:
+                rate = 1800;
+                break;
+            case 10:
+                rate = 2400;
+                break;
+            case 11:
+                rate = 3600;
+                break;
+            case 12:
+                rate = 4800;
+                break;
+            case 13:
+                rate = 7200;
+                break;
+            case 14:
+                rate = 9600;
+                break;
+            case 15:
+                rate = 19200;
+                break;
         }
+
+        setBaudRate(rate);
     }
 
 
@@ -203,13 +204,16 @@ public class Acia6551 extends Acia {
 
 
     private synchronized void reset() {
-        txChar = 0;
-        txEmpty = true;
-        rxChar = 0;
-        rxFull = false;
-        receiveIrqEnabled = false;
-        transmitIrqEnabled = false;
-        interrupt = false;
-    }
+        // Figure 6 in the 6551 ACIA data sheet says the "program reset"
+        // event does not modify the control register.
 
+        // Figure 7 in the 6551 ACIA data sheet says the "program reset"
+        // event keeps the "parity check" configuration in the command
+        // register, but resets the other bits to defaults.
+        setCommandRegister((commandRegister & 0xe0) | 0x02);
+
+        // Figure 8 in the 6551 ACIA data sheet says the "program reset"
+        // event clears the "overrun" flag but otherwise has no effect.
+        overrun = false;
+    }
 }

src/test/java/com/loomcom/symon/AciaTest.java

@@ -254,4 +254,76 @@ public class AciaTest {
 
         assertEquals(0x08, acia.read(0x0001, true));
     }
+
+    @Test
+    public void statusRegisterInitializedAtHardwareReset() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+
+        assertEquals(0x10, acia.read(0x0001, false));
+    }
+
+    @Test
+    public void commandRegisterInitializedAtHardwareReset() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+
+        assertEquals(0x02, acia.read(0x0002, false));
+    }
+
+    @Test
+    public void controlRegisterInitializedAtHardwareReset() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+
+        assertEquals(0x00, acia.read(0x0003, false));
+    }
+
+    @Test
+    public void programResetClearsOverrunStatus() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+        Bus bus = new Bus(acia.ACIA_SIZE);
+        acia.setBus(bus);
+
+        // Change as many status bits as we can.
+        acia.write(0x0002, 0x00); // enable receive interrupt
+        acia.rxWrite('a');
+        acia.rxWrite('b'); // overrun, receive full, interrupt signalled
+        acia.write(0x0000, 'c'); // Transmitter Data Register not empty
+
+        // Check that all the bits we expected to be set actually are
+        assertEquals(0x8C, acia.read(0x0001, false));
+
+        // Do a "program reset". The value is ignored.
+        acia.write(0x0001, 0xFF);
+
+        // Check that only bit 2 was cleared.
+        assertEquals(0x88, acia.read(0x0001, false));
+    }
+
+    @Test
+    public void programResetKeepsParitySettings() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+
+        // Set all the command register bits
+        acia.write(0x0002, 0xFF);
+
+        // Do a "program reset". The value is ignored.
+        acia.write(0x0001, 0xFF);
+
+        // The top 3 bits should be kept as-is,
+        // the bottom 5 bits should be reset to defaults.
+        assertEquals(0xE2, acia.read(0x0002, false));
+    }
+
+    @Test
+    public void programResetLeavesControlRegisterUnchanged() throws Exception {
+        Acia6551 acia = new Acia6551(0x0000);
+
+        // Set all the control register bits
+        acia.write(0x0003, 0xFF);
+
+        // Do a "program reset". The value is ignored.
+        acia.write(0x0001, 0xFF);
+
+        // No bits should have changed.
+        assertEquals(0xFF, acia.read(0x0003, false));
+    }
 }

src/test/java/com/loomcom/symon/CpuAbsoluteModeTest.java

@@ -29,7 +29,7 @@ public class CpuAbsoluteModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*
@@ -169,7 +169,7 @@ public class CpuAbsoluteModeTest extends TestCase {
         assertEquals(0x04, bus.read(0x1fe, true));
 
         // No flags should have changed.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /* BIT - Bit Test - $2c */
@@ -362,7 +362,7 @@ public class CpuAbsoluteModeTest extends TestCase {
         cpu.step();
         assertEquals(0x3400, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /* EOR - Exclusive OR - $4d */

src/test/java/com/loomcom/symon/CpuAbsoluteXModeTest.java

@@ -29,7 +29,7 @@ public class CpuAbsoluteXModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuAbsoluteYModeTest.java

@@ -29,7 +29,7 @@ public class CpuAbsoluteYModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuAccumulatorModeTest.java

@@ -30,7 +30,7 @@ public class CpuAccumulatorModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
    /*
@@ -306,4 +306,4 @@ public class CpuAccumulatorModeTest extends TestCase {
         assertFalse(cpu.getCarryFlag());
     }
 
-}
+}

src/test/java/com/loomcom/symon/CpuImmediateModeTest.java

@@ -29,7 +29,7 @@ public class CpuImmediateModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuImpliedModeTest.java

@@ -33,7 +33,7 @@ public class CpuImpliedModeTest {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*
@@ -76,6 +76,7 @@ public class CpuImpliedModeTest {
     public void test_BRK() throws MemoryAccessException {
         cpu.setCarryFlag();
         cpu.setOverflowFlag();
+        cpu.clearIrqDisableFlag();
         assertEquals(0x20 | Cpu.P_CARRY | Cpu.P_OVERFLOW,
                      cpu.getProcessorStatus());
         assertEquals(0x00, cpu.stackPeek());
@@ -343,7 +344,7 @@ public class CpuImpliedModeTest {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x201, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /* PHA - Push Accumulator - $48 */
@@ -432,7 +433,7 @@ public class CpuImpliedModeTest {
         cpu.step();
 
         assertEquals(0x0f12, cpu.getProgramCounter());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /* SEC - Set Carry Flag - $38 */
@@ -641,4 +642,4 @@ public class CpuImpliedModeTest {
         assertFalse(cpu.getZeroFlag());
         assertTrue(cpu.getNegativeFlag());
     }
-}
+}

src/test/java/com/loomcom/symon/CpuIndexedIndirectModeTest.java

@@ -31,7 +31,7 @@ public class CpuIndexedIndirectModeTest {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     @Test
@@ -105,4 +105,4 @@ public class CpuIndexedIndirectModeTest {
         assertEquals(0x11, cpu.getAccumulator());
         assertEquals(0x31, bus.read(0xc51f, true));
     }
-}
+}

src/test/java/com/loomcom/symon/CpuIndirectIndexedModeTest.java

@@ -31,7 +31,7 @@ public class CpuIndirectIndexedModeTest {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     @Test
@@ -81,4 +81,4 @@ public class CpuIndirectIndexedModeTest {
         assertEquals(0xe3, bus.read(0xd828, true));
     }
 
-}
+}

src/test/java/com/loomcom/symon/CpuIndirectModeTest.java

@@ -29,7 +29,7 @@ public class CpuIndirectModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*
@@ -48,7 +48,7 @@ public class CpuIndirectModeTest extends TestCase {
         cpu.step();
         assertEquals(0x5400, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     public void test_JMP_with_ROR_Bug() throws MemoryAccessException {
@@ -60,7 +60,7 @@ public class CpuIndirectModeTest extends TestCase {
         cpu.step();
         assertEquals(0x2200, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     public void test_JMP_withIndirectBug() throws MemoryAccessException {
@@ -72,7 +72,7 @@ public class CpuIndirectModeTest extends TestCase {
         cpu.step();
         assertEquals(0x2200, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     public void test_JMP_withOutIndirectBug() throws MemoryAccessException {
@@ -84,7 +84,7 @@ public class CpuIndirectModeTest extends TestCase {
         cpu.step();
         assertEquals(0x5400, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     public void test_JMP_cmos() throws MemoryAccessException {
@@ -96,7 +96,7 @@ public class CpuIndirectModeTest extends TestCase {
         cpu.step();
         assertEquals(0x5400, cpu.getProgramCounter());
         // No change to status flags.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
-}
+}

src/test/java/com/loomcom/symon/CpuIndirectXModeTest.java

@@ -28,7 +28,7 @@ public class CpuIndirectXModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuRelativeModeTest.java

@@ -29,7 +29,7 @@ public class CpuRelativeModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
   /*
@@ -278,4 +278,4 @@ public class CpuRelativeModeTest extends TestCase {
         assertEquals(0x202, cpu.getProgramCounter());
     }
 
-}
+}

src/test/java/com/loomcom/symon/CpuTest.java

@@ -44,7 +44,7 @@ public class CpuTest extends TestCase {
         assertEquals(0x0200, cpu.getProgramCounter());
         assertFalse(cpu.getCarryFlag());
         assertFalse(cpu.getZeroFlag());
-        assertFalse(cpu.getIrqDisableFlag());
+        assertTrue(cpu.getIrqDisableFlag());
         assertFalse(cpu.getDecimalModeFlag());
         assertFalse(cpu.getBreakFlag());
         assertFalse(cpu.getOverflowFlag());
@@ -205,14 +205,12 @@ public class CpuTest extends TestCase {
     }
 
     public void testGetProcessorStatus() {
-        // By default, no flags are set.  Remember, bit 5
+        // By default, only "interrupt disable" is set.  Remember, bit 5
         // is always '1'.
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
         cpu.setCarryFlag();
-        assertEquals(0x21, cpu.getProcessorStatus());
+        assertEquals(0x25, cpu.getProcessorStatus());
         cpu.setZeroFlag();
-        assertEquals(0x23, cpu.getProcessorStatus());
-        cpu.setIrqDisableFlag();
         assertEquals(0x27, cpu.getProcessorStatus());
         cpu.setDecimalModeFlag();
         assertEquals(0x2f, cpu.getProcessorStatus());
@@ -237,13 +235,16 @@ public class CpuTest extends TestCase {
         assertEquals(0xa0, cpu.getProcessorStatus());
         cpu.clearNegativeFlag();
         assertEquals(0x20, cpu.getProcessorStatus());
+
+        cpu.setIrqDisableFlag();
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     public void testSetProcessorStatus() {
         // Default
         assertFalse(cpu.getZeroFlag());
         assertFalse(cpu.getZeroFlag());
-        assertFalse(cpu.getIrqDisableFlag());
+        assertTrue(cpu.getIrqDisableFlag());
         assertFalse(cpu.getDecimalModeFlag());
         assertFalse(cpu.getBreakFlag());
         assertFalse(cpu.getOverflowFlag());
@@ -669,4 +670,4 @@ public class CpuTest extends TestCase {
         cpu.step();
         assertEquals(0x3E, cpu.getAccumulator());
     }
-}
+}

src/test/java/com/loomcom/symon/CpuZeroPageModeTest.java

@@ -29,7 +29,7 @@ public class CpuZeroPageModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuZeroPageXModeTest.java

@@ -29,7 +29,7 @@ public class CpuZeroPageXModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*

src/test/java/com/loomcom/symon/CpuZeroPageYModeTest.java

@@ -29,7 +29,7 @@ public class CpuZeroPageYModeTest extends TestCase {
         assertEquals(0, cpu.getYRegister());
         assertEquals(0x200, cpu.getProgramCounter());
         assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
+        assertEquals(0x24, cpu.getProcessorStatus());
     }
 
     /*