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-rw-r--r--src/mame/drivers/aim65.cpp9
1 files changed, 9 insertions, 0 deletions
diff --git a/src/mame/drivers/aim65.cpp b/src/mame/drivers/aim65.cpp
index d9c34e4688b..5a37b2f1758 100644
--- a/src/mame/drivers/aim65.cpp
+++ b/src/mame/drivers/aim65.cpp
@@ -33,6 +33,15 @@ Bugs
#include "aim65.lh"
+/** R6502 Clock.
+ *
+ * The R6502 on AIM65 operates at 1 MHz. The frequency reference is a 4 MHz
+ * crystal controlled oscillator. Dual D-type flip-flop Z10 divides the 4 MHz
+ * signal by four to drive the R6502 phase 0 (O0) input with a 1 MHz clock.
+ */
+static constexpr XTAL AIM65_CLOCK(4_MHz_XTAL / 4);
+
+
/***************************************************************************
ADDRESS MAPS
***************************************************************************/