[Coco] Question re: Cart slot decode

[Darren A]

On 2/2/09, jdaggett at gate.net wrote:
>
> The SCS is from $FF40 to $FF4F when the MC2 bit is "1".  When the MC2
> bit is "0" then the SCS is from $FF50 to $FF5F.
>
> The SCS line is only asserted for 16 bytes within the memory map. The
> MC2 bit selects which of two 16 byte ranges. This smacks of a potential of
> having two floopy controllers or a floopy and hard disk controller on one
> card. Access then can be done by just setting or clearing a bit in the INIT0
> register. of the GIME. Or even an internal and external floppy drive system.
>

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No.  The standard SCS is the 32-byte range of FF40 - FF5F.  The CoCo
3's non-standard SCS removes the bottom 16 bytes from that range,
restricting it to FF50 - FF5F.

Darren