Re: [cc65] Apple 2 Screen I/O Bugs

From: Oliver Schmidt <>
Date: 2009-01-12 08:25:53
Hi <whoever>,

> The last time I tried to use printf() and puts() to output reverse-video
> text to an Apple 2 screen, the emulator displayed garbage.

In general you're not suspected to mix conio and stdio functions.
However the Apple2 C-library tries everything to make them fully
compatible anyway.

The garbage you see comes from trying to display lowercase reverse
characters using the primary charset - which doesn't work for
compatiblity reasons with older software (Apple's choice, not cc65's).
You need to switch in the alternate charset. The same would be true if
you'd program i.e. in BASIC.

Just in case you don't know what I'm talking about and/or are even not
interested in these type of Apple2 specifics than just stick to the
rules and use solely conio - which takes care for you of ugly details
like the ones described above.

> Also, the
> cursor() function doesn't seem to work.

This is true - and expected, as the Apple2 doesn't have a hardware cursor.

> These were tested with the
> Apple2Enh target on cc65 version 2.12.0.  Just thought people'd like to
> know.

Most people here know about the different usecases for stdio and
conio. In general it's not that there are lots of bugs in the Apple2
C-library. So if something doesn't work as you expect you might want
to verify your expectation first bevore postulating bugs (see your
message title).

Best, Oliver
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Received on Mon Jan 12 08:25:59 2009

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