[Coco] How SLENB works ?

[Darren A]

On Fri, Jul 18, 2014 at 6:29 PM, Torsten Dittel <OS-9 at trs-80.cc> wrote:

> The more I think about it, freezing was maybe not a feature at all (what
> sense would it make to HALT if a soft-start should rather be excuted after
> a
> RESET?)
>
> But telling the CPU via the cartridge bus from an external device that a
> certain address has a certain value (despite the RAM contained actually
> another value) was definitely done using SLENB.
>

Sounds like one of Tony Distefano's projects found in "A Full Turn of the
Screw".

On a CoCo 1 or 2 you can decode a RAM address and assert SLENB to prevent
RAM selection and substitute a different value. It would not work on a CoCo
3 where SLENB has no effect on RAM selection.

Darren