Re: userport: C64, Plus4, others?

From: Jim Brain <>
Date: Tue, 06 Mar 2012 20:34:14 -0600
Message-ID: <>
On 3/6/2012 10:48 AM, Gábor Lénárt wrote:
> Hi Ruud,
> On Tue, Mar 06, 2012 at 05:13:45PM +0100,  wrote:
> And as far as I can understand the things, CIA can provide a (with 
> "PC") for the uC that new data put on (on C64 write), or data is read 
> (so next can be placed for read by the C64). 
Actually, the user port is good for this.

Handshaking will be the issue, in my opinion.  You can easily put the 
data on PortB and read it, but how do you tell the uC the data is there 
to be read, and how do you know when data is available to read?  On teh 
6522, for example, the proper signals are CA1/CA2, but they are not on 
the user port.  CB1/CB2 can provide the interrupts, but they're not as 

> The reason I'd like decent transfer rate between C64 (or DTV) and the 
> uC: I'd like to use an uC with ethernet capabilities later. Though 
> there are ethernet solutions (like TFE or RR-Net) for the C64, I 
> always felt that I want something like this for DTV too, where there 
> is no solution for the problem (and you don't have an std C64 bus at 
> all - but you have some kind of user port at least, even if it's not 
> the very same). As DTV has many memory, and I already experimented 
> with some kind of "advanced OS" (multitasking etc) for the DTV, it 
> would be really nice to have TCP/IP too (I've already have a partly 
> working stuff like that for RR-Net on C64, as uIP seems to be 
> complicated for me - and it's C - and I haven't heard too much about 
> IP65 when I started that project). But currently I want to focus only 
> a solution which provides good transfer rate between C64 and a uC 
> without thinking other topics. - Gábor Message was sent through the 
> cbm-hackers mailing list 

I'm happy to help on both sides (64, and if you want to use AVR, the uC 

You do need to ensure 2 more lines besides the 8 data lines (WRITE and 
READ, essentially). Everything else is details.


Jim Brain

       Message was sent through the cbm-hackers mailing list
Received on 2012-03-07 03:00:04

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