Re: 6561-101

Hi

to repair your vic20 you can use this product:

http://vic-20.de/x1541/hardware/petram.html

it replaces ram and/or rom...

it helped me to fix a old cbm 8032...


it is clear that if the VIC is not correctly initialized you probably 
get a black screen.




On 26/10/2016 10:33, Hegedűs István wrote:
> The problem is that this is my first ever VIC20 so I have no 
> cartridges... The idea is however good.
> Thanks
> Hege
>
>
> -----Original Message----- From: Clockmeister
> Sent: Wednesday, October 26, 2016 3:00 AM
> To: cbm-hackers@musoftware.de
> Subject: Re: 6561-101
>
>
>
> On 26/10/2016 4:38 AM, Hegedűs István wrote:
>> Hi,
>>
>> It has black screen of course. I know that the Kernal ROM or VIC used 
>> to be the guilty ones. I have burnt a 27c128 with Kernal but still 
>> have to build an adapter so I cannot 100% rule out Kernal issue. The 
>> guy who sold it said that the 6502 is also sick (he has tried the CPU 
>> in an 1541), though with oscilloscope I have seen e.g. proper phi2 
>> signal coming out. I have bought some Rockwell 6502s to replace it. 
>> Anyway even if it turns out that VIC is good it is better to have a 
>> spare IC.
>> I should hook up my logic analyzer to it but so far I had no time (or 
>> I was just too lazy).
>>
>
>
> Whilst mask ROM (and RAM for that matter) failures are common on vintage
> equipment, the last two VIC-20's with a black screen that I repaired had
> a bad 6561-101.
> In my case both were easy to diagnose by simply plugging in a cartridge
> or blind loading a game. On both occasions the game you could hear the
> game playing even though there was a black screen.
>
>
>
>
>
>       Message was sent through the cbm-hackers mailing list
>
>       Message was sent through the cbm-hackers mailing list


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