[Coco] Byte Order Question

[Robert Gault]

David Gacke wrote:


> Hi All,

> 

> I've got a byte order question and I'm sure someone on here can give me

> the correct answer.

> 

> I'm trying to figure out the byte order of 16 and 32 bit register writes

> from a 6809 and 6309 

> 

> I'll use text characters as an example.

> 

> For instance, if I have a 32 bit value of say 0x41424344  ('ABCD') and I

> were to write that to video display memory, what would I see?

> 

> Would it be:

> 

> ABCD

> 

> CDBA

> 

> DCBA

> 

> 

> Also, what about 16 bit writes of say 0x4142..

> 

> Is it 

> 

> AB or BA?

> 

> 

> I need someone to give me a sanity check while I'm coding something.  :)

> 

> Thanks a bunch!

> 

> 

> Dave

> 

> 

> 

> 

> 

One further point to add to the other responses. It depends on whether 
the text screen is the low res 32 column or high res 40/80 column 
screens on a Coco3.

On the high res screens of a Coco3, every other byte is not text but an 
attribute byte. Text screens have the following format:
even byte - character, odd byte - attribute

attribute bits
0 - 2 background palette address
3 - 5 foreground   "        "
6     underline
7     blink