315-5309

The 315-5309 is found on early revision of the MegaDrive I.

It handle the IO port and the version register

Pinout

OpenOffice Draw file : File:315-5309.odg

Address Buses
A0-A23	M68K Address Bus
ZA0-ZA15	Z80 Address bus
Data Buses
D0-D15	M68K Data bus
ZD0-ZD7	Z80 Data bus
IO port lines
EM1X	Port 1 lines
EM2X	Port 2 lines
EM3X	Port 3 lines
Control lines
/CAS0	Active low, read on $000000-$DFFFFF region
/DISK	0V Expansion Unit connected
FREQ	5V = 60Hz, 0V = 50Hz
/FRES
LANG	5V = English, 0V = Japanese
/LWR	Lower byte WRite
/M3	Mark III compatibility mode
Clock lines
VCLK	68K clock