From MegaDrive Development Wiki
Jump to navigation
Jump to search
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
|
MCLK
|
Master Clock
|
VCLK
|
68K clock
|
ZCLK
|
Z80 clock
|
EDCLK
|
Unknown clock
|