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3. BIOS transfer
4. System transfer
Transfer the data of the BIOS (collection of programs for each
of the functions to have sub-CPU access to the CD drive) and
the data of the system (program that has used the BIOS) from
the check cartridge to the program RAM. Distinction is being
made only based on what kind of dated is being transferred
to the program RAM; therefore, the "2 program RAM R/W check"
and
the
error
of the above 3 and 4 occur due
to
the
same
factor in terms of hardware.
Cause of Error: Same as 2
4. Sub-CPU reset check
The MEGA-CD system is equipped with the CPU (68000
&
Z80)
of the Mega Drive side and the CPU (68000 (!Cl) ) of the
MEGA-CD side.
For the sake of convenience, the former is
called the main CPU (or main side) and the later is called
sub-CPU (or sub side). Here, try resetting from the Mega
Drive side to the sub-CPU and check if a normal response
is returned.
Cause of Error: !Cl defect, the surroundings of G/A {gate
array IC2) etc.
*
COMMUNICATION CHECK
Check if the communication between the Mega Drive side and
the sub-CPU (ICl) goes well or not. The circuit of this
purpose is located in the G/A {IC2); therefore, the cause
of error may include G/A (Ic2) and sub-CPU (!Cl) etc.
Cause of Error: the surroundings of G/A(IC2), sub-CPU
(ICl) etc.
1. Communication flag R/W check
Perform R/W on the flag (inside G/A) required for communica-
tion and check if they function properly.
2. Communication port
Access the communication port (in G/A) and check its function.
3. Stopwatch check
Check the function of the watch located in G/A.
2
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