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Correct multiplier.

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This commit is contained in:
Thomas Harte 2021-06-20 14:25:37 -04:00
parent 09dbff39f2
commit d8b9cdf7a2
1 changed files with 7 additions and 1 deletions
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8
Machines/Enterprise/Enterprise.cpp
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@ -46,6 +46,12 @@ namespace Enterprise {
=> one cycle = 45440000 / 709379*912 = 45440000 / 646953648 = 2840000 / 40434603 µs
=> clock rate of 40434603 / 2840000 Mhz
And, therefore, the ratio to a 4Mhz Z80 clock is:
40434603 / (2840000 * 4)
= 40434603 / 11360000
i.e. roughly 3.55 Nick cycles per Z80 cycle.
If that's true then the 6-cycle window is around 1.69 Z80 cycles long. Given that the Z80
clock in an Enterprise can be stopped in half-cycle increments only, the Z80 can only be
guaranteed to have around a 1.19 cycle minimum for its actual access. I'm therefore further
@ -373,7 +379,7 @@ class ConcreteMachine:
// MARK: - Chips.
CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
JustInTimeActor<Nick, HalfCycles, 40434603, 2840000> nick_;
JustInTimeActor<Nick, HalfCycles, 40434603, 11360000> nick_;
bool previous_nick_interrupt_line_ = false;
// Cf. timing guesses above.
};