From eecea93b3b235777c3256bd1173ea154279e3355 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 1 May 2018 21:31:37 -0400
Subject: [PATCH] Simplifies the test for resetting the ZX80/81 line counter.

---
 Machines/ZX8081/ZX8081.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/Machines/ZX8081/ZX8081.cpp b/Machines/ZX8081/ZX8081.cpp
index fd15e1e46..ade679f17 100644
--- a/Machines/ZX8081/ZX8081.cpp
+++ b/Machines/ZX8081/ZX8081.cpp
@@ -124,14 +124,12 @@ template<bool is_zx81> class ConcreteMachine:
 			bool is_opcode_read = false;
 			switch(cycle.operation) {
 				case CPU::Z80::PartialMachineCycle::Output:
-					if(!(address & 2)) nmi_is_enabled_ = false;
-					if(!(address & 1)) nmi_is_enabled_ = is_zx81_;
 					if(!nmi_is_enabled_) {
-						// Line counter reset is held low while vsync is active; simulate that lazily by performing
-						// an instant reset upon the transition from active to inactive.
-						if(vsync_) line_counter_ = 0;
+						line_counter_ = 0;
 						set_vsync(false);
 					}
+					if(!(address & 2)) nmi_is_enabled_ = false;
+					if(!(address & 1)) nmi_is_enabled_ = is_zx81_;
 
 					// The below emulates the ZonX AY expansion device.
 					if(is_zx81) {