4 Mar 2007

Emulator 2 memory error

A "craaak" in the sound, or an erratic behaviour.

Explanation : Some of the sound memory is used as "scratchpad" memory, for the system.

The memory is arranged, if I remember well, in a block of 8x8 chips (unless
you dont have the piggyback additional memory board).

First : take away ALL the memory chips by remembering their location and
intervert them.
Is there a change ?

If the machine boots okay now, just sample music at maximum length (all the
memory).

Listen to it. Is there a "crakkk" sound somewhere ? How long does it take
to come ?

Now, intervert one quarter of the memories to another quarter

Sample again.

The cracckkkk sound has changed, in terme of the moment it occurs ? No ?
This means that the two quarters you have sawpped around are good chips.

Now, locate another quarter of the the (one of the two you didn't move) and
swap the two halves of them. Location of the crackk has changed ? Yes ? You
are close to it. Now, swap the half of the quarter in two halves. Etc...

At last, you will find the faulty chip. In teh WORSE case, it will take six
operations to find a faulty chip out of 64 chips and 16 operations to find
a faulty chip out of for 65536.

Now, finding a chip somewhere is gonna be something else...

Thanks to Dr.C for providing this info.

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