Tim Allen
b5a470d3ba
When describing the CPU's reset pin, the W65C02S data sheet says: > All Registers are initialized by software except the Decimal and Interrupt > disable mode select bits of the Processor Status Register (P) are initialized > by hardware. It then has a diagram of the power-on state of the processor status register: > 7 6 5 4 3 2 1 0 > * * 1 1 0 1 * * > N V - B D I Z C > > * = software initialized Confusingly the text indicates that only the D and I flags are initialised by hardware, while the diagram indicates that the B flag is initialised too. Meanwhile, https://www.nesdev.org/wiki/CPU_power_up_state says that the power-on state of the NES CPU is $34 (exactly matching the diagram above) but https://www.nesdev.org/wiki/Status_flags#The_B_flag says that the B flag does not physically exist within P register, it's only relevant in the copy of P that gets pushed to the stack by BRK (set), PHP (set), or an interrupt signal (cleared). As a result, the most sensible power-on state for the processor status register is with the "interrupt disable" flag set and everything else cleared.
85 lines
2.2 KiB
Java
85 lines
2.2 KiB
Java
package com.loomcom.symon;
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import com.loomcom.symon.devices.Memory;
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import org.junit.*;
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import static org.junit.Assert.*;
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public class CpuIndirectIndexedModeTest {
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protected Cpu cpu;
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protected Bus bus;
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protected Memory mem;
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@Before
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public void runBeforeEveryTest() throws Exception {
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this.cpu = new Cpu();
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this.bus = new Bus(0x0000, 0xffff);
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this.mem = new Memory(0x0000, 0xffff);
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bus.addCpu(cpu);
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bus.addDevice(mem);
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// Load the reset vector.
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bus.write(0xfffc, Bus.DEFAULT_LOAD_ADDRESS & 0x00ff);
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bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00) >>> 8);
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cpu.reset();
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// Assert initial state
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assertEquals(0, cpu.getAccumulator());
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assertEquals(0, cpu.getXRegister());
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assertEquals(0, cpu.getYRegister());
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assertEquals(0x200, cpu.getProgramCounter());
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assertEquals(0xff, cpu.getStackPointer());
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assertEquals(0x24, cpu.getProcessorStatus());
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}
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@Test
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public void test_LDA() throws Exception {
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assertEquals(cpu.toString(), 0x00, cpu.getAccumulator());
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bus.write(0x0014, 0x00);
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bus.write(0x0015, 0xd8);
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bus.write(0xd828, 0x03);
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cpu.setYRegister(0x28);
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bus.loadProgram(0xb1, 0x14); // LDA ($14),Y
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cpu.step(1);
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assertEquals(0x03, cpu.getAccumulator());
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}
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@Test
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public void test_ORA() throws Exception {
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bus.write(0x0014, 0x00);
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bus.write(0x0015, 0xd8);
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bus.write(0xd828, 0xe3);
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cpu.setYRegister(0x28);
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cpu.setAccumulator(0x32);
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bus.loadProgram(0x11, 0x14); // ORA ($14),Y
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cpu.step(1);
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assertEquals(0xf3, cpu.getAccumulator());
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assertEquals(0xe3, bus.read(0xd828, true));
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}
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@Test
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public void test_AND() throws Exception {
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bus.write(0x0014, 0x00);
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bus.write(0x0015, 0xd8);
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bus.write(0xd828, 0xe3);
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cpu.setYRegister(0x28);
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cpu.setAccumulator(0x32);
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bus.loadProgram(0x31, 0x14); // AND ($14),Y
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cpu.step(1);
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assertEquals(0x22, cpu.getAccumulator());
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assertEquals(0xe3, bus.read(0xd828, true));
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}
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}
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