RE: Random Characters

From: Ed Johnson <>
Date: Mon, 6 Feb 2012 19:23:56 -0500
Message-ID: <703255F3B2D3427E83F60B066909F3EF@dell6400>
Thanks for all the help. The new PLA arrived today.
I performed the surgery on it and the patient is
doing fine. It actually seems to have clearer video.

Now to fix the sound...

Best regards,
Ed Johnson

-----Original Message-----
From: Rob Clarke [] 
Sent: Sunday, January 29, 2012 10:10 AM
Cc: Ed Johnson
Subject: Re: Random Characters

Some early boards do not have the commodore part number on the PLA. In this
particular photo it's below the 6510 (cpu) and to the left of the
6581 (SID).

If it is the PLA at fault, you can buy a new one here: or buy a
modern replacement here :


On 29/01/2012 16:01, Ed Johnson wrote:
> I don't see that chip. Can you identify it in this photo?
> -----Original Message-----
> From:
> [] On Behalf Of Gerrit Heitsch
> Sent: Sunday, January 29, 2012 8:56 AM
> To:
> Subject: Re: Random Characters
> On 01/29/2012 02:29 PM, Ed Johnson wrote:
>> I have a C64 that displays random characters on the screen and locks 
>> up when powered on. Sometimes it powers on correctly but within 
>> seconds displays random characters and locks up. I bought it off eBay 
>> and it worked fine for about a week of heavy use but then this 
>> problem
> started.
> The usual suspects in this case are the PLA (906114-01), the 74LS258, 
> the CIA that supplies the 2 extra address bits for the VIC and maybe the
> Also, if any of the chips I mentioned are in sockets, see if removing 
> them and putting them back in helps.
>    Gerrit
>         Message was sent through the cbm-hackers mailing list
>         Message was sent through the cbm-hackers mailing list

       Message was sent through the cbm-hackers mailing list
Received on 2012-02-07 01:00:03

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