diff options
Diffstat (limited to 'src/mame/drivers/fidel68k.cpp')
-rw-r--r-- | src/mame/drivers/fidel68k.cpp | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/src/mame/drivers/fidel68k.cpp b/src/mame/drivers/fidel68k.cpp index a9d2c6c083b..46f28ec73e8 100644 --- a/src/mame/drivers/fidel68k.cpp +++ b/src/mame/drivers/fidel68k.cpp @@ -56,10 +56,9 @@ Hardware info: - OKI M82C51A-2 USART, 4.9152MHz XTAL - other special: magnet sensors, external module slot, serial port -IRQ source is unknown. Several possibilities: -- NE555 timer IC -- MM/SN74HC4060 binary counter IC (near the M82C51A) -- one of the XTALs, plus divider of course +IRQ source is a 4,9152MHz quartz crystal (Y3) connected to a 74HC4060 (U8, +ripple counter/divider). From Q12 output (counter=8192) we obtain the IRQ signal +applied to IPL1 of 68000 (pin 24) 4,9152 MHz / 8192 = 600 Hz. The module slot pinout is different from SCC series. The data on those appears to be compatible with EAG though and will load fine with an adapter. |