Re: Carte Blanche and Apples other than 2e

[IUnknown <stevementzer@gmail.com>]

On Oct 4, 1:59 am, Alex Freed <alex_n...@mirrow.com> wrote:
> It came to my attention that the image selection from a keyboard doesn't
> always work right on a 2GS. I also know that it doesn't work on a 2+.
> This is not exactly a "bug" - rather the implementation is model specific.
>
> To get the keyboard input CB monitors the Apple bus as it appears on the
> slot connector. If it detects a read from $C000 and the high bit of the
> data is set it is taken as a keyboard pressed event. Now it gets a bit
> technical. The signals available on the bus are Q3 and PH0 among others.
> In most cases the data is valid on a falling edge of the Q3 signal
> during PH0 high phase of the system clock. This is fine for latching the
> keyboard access on a 2+. Unfortunately the 2e uses a different design
> and the keyboad data becomes valid later than that. It also stays valid
> longer and can be latched on a falling edge of the ph0 itself. Since the
> vast majority of the A2s are of the 2e variety I chose to use the 2e
> timing in the default design.
> If the 2+ timing is preferred it is a single Verilog line change.
> Unfortunately a fix that would work for *both* is not quite as simple.
> Not terribly hard either - just make a state machine running off the 50
> MHz system clock to latch the data somewhere at the right moment that
> works for both 2+ and 2e. Chances are it will also work for the GS.
>
> I will probably do it eventually (if nobody does it before I do) but it
> is  not a first priority.
>
> As for the VGA for GS the current design will support the standard video
> modes but not GS specific ones and not even the double-hires. Can be
> done but not the top priority either.
>
> -Alex.


Alex,

Is the IIgs support going to become a higher priority for you at some
point? I realize that the first lot of cards have sold out, but I
would have purchased one if I knew that you had short-term plans to
support the IIgs video modes.  I really have no interest in a CB for
my IIe because games work fine on a 14" composite monitor... whereas
the IIgs sitting on my desk is begging to be connected to a VGA
monitor or modern LCD :)

Just a question....