From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2005-11-28 12:47:12
On Mon, Nov 28, 2005 at 11:05:07AM +0100, MagerValp wrote:
> You have to keep a shadow register if you want to read back the value.
Using a shadow register is ok if you're assuming that one guy writes one
program that is in control of the whole machine. If you try to make things
more modular and create reusable code for other peoples programs, this
solution starts to suck. Assume a cc65 loadable driver: It is rather difficult
to access such a shadow register from the driver. Or assume that you're
linking together modules from different sources: The programmers writing these
modules must use the same shadow register or you will run into trouble.
After some contemplating, I think I can live with the $d03f register not being
readable, if I do assume that access to the extended registers must always be
possible on a DTV and the INSTALL routine of the driver enforcing this by
enabling access. But it's still only the second best solution.
I don't know if there are plans for a D3TV, but if there are any, how about a
wishlist?
1. Fix the color issue (this one looks like a problem created by the
production engineers).
2. Add a command/register to read the current register assignments.
3. Make important config registers (like $d03f) readable.
4. ?
BTW, does the DTV have the "jmp ($XXFF)" bug?
Regards
Uz
--
Ullrich von Bassewitz uz@musoftware.de
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