Re: Serial IEC bus for PETs
Date: 2000-11-08 20:31:05


> That's why I opted for the VIC-20 routines in the first place. However,
> Ruud has a point here: The C64-kernal is available in source, the VIC-20
> one isn't, AFAIK.

To be honest, I haven't thought about the VIC-20 at all. The reasons to choose 
for Andre's SW was 1) the differences between the 6526 and 6522 2) I thought I 
would be better of with a source which isn't "poluted" with lots of other 
routines. 3) I thought Andre's converter used a 6522
I downloaded the SW and then I found out it used a 6532. But writing the 
previous sentence the thought struck me that the PET/CBM uses a 6520 for the 
userport. So what ever SRC we use, some conversion is needed. 

The first hurdle is the need for a timer. I'm not familiar with the Kernal of 
the CBM so I wonder if the timer of the 6522 can be used for this purpose? If 
so, we have to lent at least this part from the VIC-20.
I was thinking of placing the SW in an EPROM in the $9000 or $A000 area. Does 
the CBM work with vectors thru RAM as the C64 does? If no, it means writing a 
userinterface as well.

Concerning the SRC of the VIC-20, the Data Becker book "64 Intern" contains a 
list of routines and where to find them in the C64 as well as in the VIC-20. 

Groetjes, Ruud

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