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Correct some 8080 timing mistakes

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This commit is contained in:
Adrian Conlon committed 2026-03-27 18:16:09 +00:00
1 parent c587da19c4
commit 47baff3740
2 files changed
+25 -7
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EightBit/IntelProcessor.cs
+1 -1
View File
@@ -205,7 +205,7 @@ namespace EightBit
this.Call();
}
protected void CallConditional(bool condition)
protected virtual void CallConditional(bool condition)
{
this.FetchInto(this.MEMPTR);
if (condition)
Intel8080/Intel8080.cs
+24 -6
View File
@@ -97,7 +97,7 @@ namespace Intel8080
this._resetPending = true;
}
private void MemoryUpdate(int ticks)
private void MemoryUpdate(int ticks = 1)
{
Debug.Assert(ticks > 0, "Ticks must be greater than zero");
this.OnWritingMemory();
@@ -109,7 +109,7 @@ namespace Intel8080
protected override void MemoryWrite()
{
this.MemoryUpdate(1);
this.MemoryUpdate();
}
protected override byte MemoryRead()
@@ -132,7 +132,7 @@ namespace Intel8080
private byte ReadDataUnderInterrupt()
{
this.Tick(4);
this.Tick(5);
return this.Bus.Data;
}
@@ -320,7 +320,7 @@ namespace Intel8080
break;
case 1: // ADD HL,rp
this.HL.Assign(this.Add(this.HL, this.RP(p)));
this.Tick(7);
this.Tick(6);
break;
default:
throw new NotSupportedException("Invalid operation mode");
@@ -388,13 +388,15 @@ namespace Intel8080
1 => this.RP(p).Decrement(),
_ => throw new NotSupportedException("Invalid operation mode"),
};
this.Tick(2);
this.Tick();
break;
case 4: // 8-bit INC
this.R(y, this.Increment(this.R(y)), 2);
this.Tick();
break;
case 5: // 8-bit DEC
this.R(y, this.Decrement(this.R(y)), 2);
this.Tick();
break;
case 6: // 8-bit load immediate
this.R(y, this.FetchByte(), 2);// LD r,n
@@ -443,6 +445,7 @@ namespace Intel8080
else
{
this.R(y, this.R(z));
this.Tick();
}
break;
case 2:
@@ -499,6 +502,7 @@ namespace Intel8080
break;
case 2: // JP HL
this.Jump(this.HL);
this.Tick();
break;
case 3: // LD SP,HL
this.SP.Assign(this.HL);
@@ -536,6 +540,7 @@ namespace Intel8080
case 5: // EX DE,HL
(this.HL.Low, this.DE.Low) = (this.DE.Low, this.HL.Low);
(this.HL.High, this.DE.High) = (this.DE.High, this.HL.High);
this.Tick();
break;
case 6: // DI
this.DisableInterrupts();
@@ -650,6 +655,19 @@ namespace Intel8080
_ => throw new ArgumentOutOfRangeException(nameof(flag)),
};
protected sealed override void CallConditional(bool condition)
{
this.FetchInto(this.MEMPTR);
if (condition)
{
this.Call();
}
else
{
this.Tick();
}
}
protected sealed override void ReturnConditionalFlag(int flag)
{
var condition = this.ConvertCondition(flag);
@@ -786,7 +804,7 @@ namespace Intel8080
_ = this.Bus.Address.Decrement();
this.Bus.Data = exchange.Low;
exchange.Low = this.MEMPTR.Low;
this.MemoryUpdate(1);
this.MemoryUpdate();
this.Tick(2);
}