[Coco] Re: Re: [Color Computer] Re: Adapter from Coo3 to SVGA

[Kevin Diggs]

Hi,

jdaggett at gate.net wrote:

> Rodney

> 

> Here is a better explanation.

> 

> When you write to $FF22 you will write to the GIME chip i nternal register at $FF22. 

> Internal to the GIME this register is a write only register. So that the old Coco1/2 bits 

> for mode control of the 6847 will be maintained. A read of that address address will 

> actually read from the PIA chip. 

> 

> Thus PB3 to PB7 of the PIA chip can actually be used as general purpose inputs 

> only. I was in error when I said that they could be used as general purpose I/O (input 

> and/or output).

> 

> james

> 


	Didn't the PIAs in the unis and deuces use sloppy decoding. An entire 
32 byte block was assigned when only 4 are needed. Didn't they just 
repeat? i.e. $ff24-$ff27 == $ff20-$ff23? Does the GIME also do this? If 
not could we just use $ff24-$ff27 for output?

					kevin