Re: Unknown 1541 add-on card

From: Gerrit Heitsch <>
Date: Wed, 26 Jun 2013 17:41:33 +0200
Message-ID: <>
On 06/25/2013 10:00 PM, wrote:
> On 2013-06-25, at 21:37, Gerrit Heitsch wrote:
>> I did take a look at the TTL support logic. It's the same as on TurboTrans 3.0, the Rossmoeller Product you mentioned. The only difference is that it contains only the RAM, ROM socket and CPU socket, not one for the VIA.
>> I'd be very surprised if it wasn't for a 1541, maybe for the newer PCB revision with the single ROM? The one known as the 1541C.
> Hmm.. How would it transfer the data then to the computer then?

You could just grab the port pins directly from the VIA for example.

But there is another possibility. This PCB could have been used for a 
copy station. The code might have copied the first disk that is inserted 
after power up into the 256KB RAM and then just dumped it onto any 
subsequently inserted disk. Or it was a prototype for the TurboTrans 3.0 
that later got the socket for the VIA and the cable to the C64 added.

Without the EPROM for it, will never know... The current state is just a 
source for a few TTLs and 8 41256 DRAMs that could come in handy for 
repairing old hardware.

> Basically I see no reason to put that much RAM into a 1541 unless it is a sort of whole disk cache. Either for access/transfer or e.g. low level copy purposes.

Well, the idea behing TT 3.0 was to cache a whole disk and allow fast 


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Received on 2013-06-26 16:00:09

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