Re: I/O Space is a Valuable Thing

From: Marko Mäkelä (
Date: 1999-10-25 21:51:58

On Mon, 25 Oct 1999, Mike Naberezny wrote:

> I remember a few months back someone was attempting to start a list of
> what devices use which I/O ranges.  Do you guys know what areas these
> devices (RL, REU, SL/T232) actually occupy in $DE and $DF?

Wasn't this discussed a few months ago here?  Someone was going to compose
a list of the addresses.  Maybe Richard Atkinson?  Anyway, the REU
occupies $df00-$df0a or so, and there are mirrors at $df10,... (or maybe
it was $df20; I don't have the REU at hand right now).  I modified one REU
so that it can coexist with an Action Replay cart (which uses $de00-$deff
for one 7-bit write-only register and $df00-$dfff for ROM or RAM).  The
modification was a 3-position switch that would choose the REU registers
to be read/write, write-only or completely disabled.  In write-only mode,
detecting the REU reliably is impossible, and not many programs are likely
to work in that mode.  But prlink does work. :-)

> I sent CMD a few e-mails but it must be a secret because they have
> ignored my (very polite) requests.

Maybe they are afraid of people making clones? :-)


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