Re: Clock Card?

[Linards Ticmanis <ticmanis@coli.uni-sb.de>]

Bill Garber wrote:

> Yes, I did. I tried ProDOS users.disk and it claims there is no
> time or date. I tried reading the eprom, however I am not sure
> if I should read C400 or CC00. They don't display the same
> info. It is a 2764 which is I believe 8k so I'm not sure how that
> would read since $100 is all that will fit in the slot memory.
> How do I find out where the firmware is loading into RAM?
> You would think just about any clock software would find it.
> ThunderClock software searches the slots, finds none. NSC
> looks for it and finds none of course since it isn't looking in a
> slot at all. ProDOS seems to find nothing. I don't know what to
> try next.

With most cards which have a 2732, $100 bytes are mapped into the "slot
x space" $Cx00-$CxFF directly, and the whole $800 are mapped from
$C800-$CFFF as soon as you acesss the slot space. Advantages are: More
room, and the ability to use absolute adresses in that adress space (as
its start adress doesn't vary from slot to slot.) The latter mapping
goes away again if $CFFF is accessed, as far as I remember.

I'd assume that of the 2764 maybe only half is used and the other half
isn't. Or it is mapped into the $C800 space in two separate banks
somehow, but 4K sounds like overkill for a clock card.

-- 

Linards Ticmanis

 The Master said, "The business of laying on the colors follows the
preparation of the plain ground."