Re: Inverse Problem on Contiki - website updated

[mjmahon@aol.com (Michael J. Mahon)]

Glenn Jones wrote:

>> Okay .. I have a nasty patch worked out that lets Contiki display inverse
>> upper and lower case characters in 80 column mode under kegs... been
>> cranking on this tiny little patch for a few hours ..it's amazing what you
>> forget over the years...
>>
>> I ended up writing a little code to detemine if the character was
>uppercase
>> or lowercase and applying the appropriate flag as required. You must use
>the
>> alternate character set $C00F softswitch (inverse lowercase replaces
>> flashing characters) -- thanks Steve "uso" :O)
>>
>> The patched code is part of the cc65 apple2 library support .. not contiki
>> .... a proper solution needs to be worked out ...

If the problem is getting the screen to look like what the C source
says it should, then it sounds like patching the cc65 apple2 library
is exactly the right thing to do.

The problem is figuring out how a C programmer should be able to
control the various video character sets that the later Apple IIs make
available.

For example, if C uses an embedded control character in a string
to shift from normal to inverse text, independent of case, then your
library patch sounds right.  If the C programmer is expected to call
auxiliary routines to switch character sets, then that's the way to go.

Since the Commodore machines also have alternate sets, no doubt
someone has already picked a style for C to use.  If it's not too
wierd, extending the same mechanism to the Apple II sounds right.

A related example is the "high ASCII" issue.  If the C programmer
expects low ASCII for portable code, then the apple2 library should
OR on the high bit (perhaps based on a character set mode variable).

-michael

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