[Simh] IO ports 8 bit bidirectional like in C64

[Clem cole]

Bill

The 8 bit I/O ports on the C64 are based on the MOS Technology 6500 Family parts. The first of these was the 6520 PIA.  You can Check http://www.6502.org/documents/datasheets/mos/ for the datasheets.  By the time of the C64 I believe they were using the 6522 but I've forgotten. Google is your friend here. 

Btw the 6502 was the most used microprocessor for a very long time.  This is different from the most used in new designs (which in thoses days was the Z80). But the be sides being in all the Apple devices and other small personal computers from my favorite (KIM-1) and the C64 it was used in many game decks, arcade equipment  and became the definition of the "toaster" processor during the C standards meetings because it was hidden in so many things. 

Clem

Sent from my iPhone

> On Jun 27, 2015, at 8:59 PM, Bill Cunningham <billcun at suddenlink.net> wrote:
> 
>     I am looking at this page...
>  
> http://www.mikroe.com/chapters/view/4/chapter-3-i-o-ports/
>  
> Now would this be similar or what the C64 MOS processor would be like? The specs I got ahold of says "8 bit bidirectional IO ports" I don't know who is familiar with the commodore 64s. But it's something to think about. I was also ready the APIs IO functions in simh.doc.
>  
>     One thing in C I haven't got to is this idea of function return types being in parenthesis. What's that for? I have seen it several times.
>  
> Bill
>  
> _______________________________________________
> Simh mailing list
> Simh at trailing-edge.com
> http://mailman.trailing-edge.com/mailman/listinfo/simh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.trailing-edge.com/pipermail/simh/attachments/20150627/0ae2120a/attachment.html>