Re: Copy Protection of PET cassettes - Flash Attack.

From: Daniel Kahlin <>
Date: Tue, 10 Aug 2010 16:33:08 +0200 (CEST)
Message-ID: <>
On Tue, 10 Aug 2010, Anders Carlsson wrote:

> Daniel Kahlin wrote:
>> Anyway a quick analysis shows that the game loads $027A-$2000. The first 
>> chunk at $027A looks like a cassette header indicating a file "FLASH 
>> ATTACK" $03FD-$2000
> Bill Degnan wrote:
>> Yes.  Now try to save this to cassette using the TIM prompt using standard 
>> procedure.  Something prevents dumping the memory to tape.
> While I haven't studied the PET memory map recently, isn't $03FD part of the 
> cassette buffer? If so, perhaps the computer rebuilds that part of memory 
> when you save in a normal way, and you lose whatever was there.

From what I can tell it isn't part of the cassette buffer.  Judging from 
the flash attack file there is space for two cassette buffers.
One from $027A-$0339 and one from $033A to $03F9.
Though, the layout in the flash attack file could be a decoy.

I'm leaning towards that there might be a different low limit for tape
saving on the PET.  IIRC this limit is $0300 on the C64 and VIC20.

Will check in vice when I get home tonight.


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Received on 2010-08-10 14:33:08

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