100 lines
2.6 KiB
C#
100 lines
2.6 KiB
C#
namespace EMU7800.Core
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{
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/// <summary>
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/// CBS RAM Plus 12KB bankswitched carts with 128 bytes of RAM.
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/// </summary>
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public sealed class CartCBS12K : Cart
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{
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//
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// Cart Format Mapping to ROM Address Space
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// Bank1: 0x0000:0x1000 Bank1:0x1000:0x1000 Select Segment: 0ff8-0ffa
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// Bank2: 0x1000:0x1000
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// Bank3: 0x2000:0x1000
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// Shadows ROM
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// 0x1000:0x80 RAM write port
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// 0x1080:0x80 RAM read port
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//
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ushort BankBaseAddr;
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readonly byte[] RAM;
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int Bank
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{
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set { BankBaseAddr = (ushort)(value * 0x1000); }
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}
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#region IDevice Members
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public override void Reset()
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{
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Bank = 2;
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}
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public override byte this[ushort addr]
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{
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get
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{
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addr &= 0x0fff;
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if (addr < 0x0200 && addr >= 0x0100)
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{
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return RAM[addr & 0xff];
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}
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UpdateBank(addr);
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return ROM[BankBaseAddr + addr];
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}
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set
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{
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addr &= 0x0fff;
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if (addr < 0x0100)
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{
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RAM[addr & 0xff] = value;
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return;
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}
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UpdateBank(addr);
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}
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}
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#endregion
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private CartCBS12K()
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{
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}
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public CartCBS12K(byte[] romBytes)
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{
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LoadRom(romBytes, 0x3000);
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Bank = 2;
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RAM = new byte[0x100];
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}
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void UpdateBank(ushort addr)
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{
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if (addr < 0x0ff8 || addr > 0x0ffa) { }
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else
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{
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Bank = addr - 0x0ff8;
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}
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}
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#region Serialization Members
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public CartCBS12K(DeserializationContext input, MachineBase m) : base(input)
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{
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input.CheckVersion(1);
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LoadRom(input.ReadExpectedBytes(0x3000), 0x3000);
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RAM = input.ReadExpectedBytes(0x100);
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BankBaseAddr = input.ReadUInt16();
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}
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public override void GetObjectData(SerializationContext output)
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{
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base.GetObjectData(output);
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output.WriteVersion(1);
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output.Write(ROM);
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output.Write(RAM);
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output.Write(BankBaseAddr);
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}
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#endregion
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}
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} |