Sega Mega-CD - BIOS Transfer; System Transfer; Sub-CPU Reset Check; Communication Check

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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

(ICl)

)

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:

ICl

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

(ICl)

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

3J