[Coco] SCS - $FF40 behavior

[RETRO Innovations]

On 10/16/2015 12:04 AM, Chad H wrote:
> What do you mean "only after banking in the ROMs"?  From what I observed on my CoCo 2, a simple PEEK or POKE triggered the SCS line low for a few microseconds then it was released.  Is the CoCo 3 doing something different here?
Sorry, I confused two things.

Yes, $ff40 will drop SCS

But, to read from the ROM space on the Coco, you have to bank it in:

 > On a Coco3 you must force ROM mode before attempting to read the 
external ROM. So, first POKE&HFFDE,0 and then try to read the Typing 
cart; ?PEEK(&HC000).