Sega Mega-CD - Word RAM Part; Peripheral IC; CD Interface Part

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*

WORD

RAM

PART

(IC11,_IC12)

Check

the

functions

related

to

the

word

RAM

(ICll,

IC12).

The

word

RAM

executes

programs

and

performs

data

processing

for

graphic

rotation

etc.

Causes

of

Error

here

can

include

·the

G/A

(IC2)

and

word

RAM

parts.

Cause

of

Error:

the

surroundings

of

G/A

(IC2)

and

word

RANG

(ICll,

IC12),

pattern

disconnection

between

the

two.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

•

if

there

are

some

passing

items

in

the

followings,

the

possibility

of

pattern

disconnection

is

considered

to

be

low.

2M

mode

R/W

check

2M

mode

select

check

Graphic

mode

check

Graphic

overwrite

mode

check

Graphic

underwrite

mode

check

1M

mode

R/W

check

1M

mode

swap

check

1M

mode

overwrite

mode

check

1M

mode

underwrite

mode

check

VRAM

image

check

Word

RAM

to

VRAM

DMA

check

* PERIPHERAL

IC

Check

peripheral

res.

One

is

to

check

the

access

to

the

PCM

RAM

(IC13,

14),

and

another

is

to

check

the

function

of

the

backup

RAM

(IC10).

1.

PCM

wave

memory

R/W

check

Cause

of

Error:

the

surroundings

of

PCM

IC

(IC3)

and

PCM

RAM

(

IC13,

14)

2.

Backup

RAM

check

Cause

of

Error:

the

surroundings

of

Backup

RAM

(IClO),

battery

(BTl),

backup

power

control

IC

(IC9)

*

CD

INTERFACE

PART

Check

whether

the

interchange

with

the

CD

drive

can

be

carried

out

properly,

or

whether

the

CD

drive

itself

operates

properly.

Cause

of

Error:

the

surroundings

of

G/A

(Ic2),

CNl,

the

connect

-ing

cable

between

CNl

and

CD

drive

etc.

3

33