Re: C64 won't let me send my data during Talk

From: Chris Osborn <fozztexx_at_fozztexx.com>
Date: Mon, 10 Jun 2013 07:21:34 -0700
Message-Id: <7720B3EB-030E-4F20-98A8-6B39BB7B03CA@fozztexx.com>
On Jun 10, 2013, at 12:59 AM, Michał Pleban wrote:

> There is an excellent document I found here:
> 
> http://jderogee.tripod.com/projects/1541-III/files/IEC_disected-IEC_1541_info.pdf
> 
> It describes various timings and other quirks of IEC, it has helped me a
> lot to understand things.

Yah, I've been reading that doc for a month or so. It's ok, but it does have a mistake and it's actually poorly written. I ended up having to hunt down some DOS code to get as much working as I have. I've even tried copying the timings of the DOS code for the talk phase, and it still doesn't work for me. 

I also was pointed to this book:

http://www.bombjack.org/commodore/books/pdf/Compute's_Vic-20_Commodore_64_Tool_Kit_Kernal.zip

It describes what the C64 is doing during each phase, but it's not a complete disassembly. It mentions something about if the first byte isn't sent "fast enough" then it will error, but it doesn't indicate if it means the entire byte has to be sent fast enough, or if it takes too long after raising CLK before it gets lowered again before sending the first bit. The way it's written also makes it sound like it does that only for the first byte and also might look at the value of the first byte.



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Received on 2013-06-10 15:01:28

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