If detected, the program refuses to run, preventing a crash.
The check only works with SpartaDOS. I don't have an overview which
DOSes potentially use the RAM under the ROM. Or which other installed
programs might use it.
No additional runtime memory space is consumed, since the change
is in the "system check" load chunk which gets replaced by the
user program during loading.
Although documented nowhere (!!!) ProDOS trashes the random counter locations $4E/$4F. Is discovered this because my TCP connections didn't have random local ports.
It's a really funny coincidence that David Finnigan discovered only 3 years ago the very same issue because of the very same reason: https://groups.google.com/forum/#!topic/comp.sys.apple2.programmer/1ciep_Oetvo
In order to have randomize() work as expected (and the Apple II random number generation in general) it is necessary to update the random counter during keypress wait just like the ROM function does.
Extendend memory is mapped over the main memory in the 0x4000..0x7FFF
area. Many DOSes disable interrupts while extended memory is banked in,
but not all (e.g. SpartaDOS-X).
This change modifies the initial interrupt handler to map in main memory
before chaining to the "worker" handlers.
Since the initial interrupt handler uses a data segment to store the
trampoline to chain to the original handler, introduce a new "LOWBSS"
segment to hold this trampoline. Otherwise the trampoline may end up
inside the 0x4000..0x7FFF area.
Add a link time warning if "LOWCODE" segment lays within the extended
memory window.
Looks like no one ever tried this? fopen was returning EINVAL because
fgets was leaving a trailing newline at the end of the filename.
(Which is what fgets is documented to do.)
Fixes this issue:
https://github.com/cc65/cc65/issues/722
ftell() returns the value returned by lseek(), and lseek() for the
Apple II wasn't returning a value.
According to https://github.com/cc65/wiki/wiki/Direct-console-IO it is undefined what happens when the end of the sceen is reached. But it is _not_ undefined what happens when the end of the line is reached. So implement the usual thing - which was easy enough to do after all.
