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Atari++ 1.70 [message #31361] Thu, 03 January 2013 15:03
Azrael is currently offline  Azrael
Messages: 215
Registered: July 2012
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Senior Member
Changes in this Atari 8-bit computer emulator for Windows and Linux include:

- Priority engine for the "fifth player" generated by missles was
redesigned and should now reproduce all possible cases, including the
priority conflicts correctly.
- Color mixing of the fifth player on top of GTIA modes C0 and 40 should
now work correctly.
- Timing of the GTIA "strange mode" where PF0 to PF3 are used for a
HIRES generated playfield was made more precise.
- Color lookup for GTIA modes C0 and 40 on top of non-HIRES ANTIC modes
was fixed.
- Player-playfield color mixing for GTIA mode 80 was fixed.
- Experimental support for on-line player and missile resizing was added.
- ANTIC display generation was re-designed yet again and was rewritten.
- ANTIC DLI and NMI timing was made a lot more precise and should now
work to the cycle.
- ANTIC VSCROLL support should now work to the cycle.
- ANTIC DMA cycle allocation should now be finally correct for all modes.
- Added emulation for ANTIC forgetting the sync signal if the last line
on the screen is HIRES.
- Added emulation of carrying the DLI and VSCROLL information across
vertical blanks from the last displayed scan-line.
- The jump on vertical blank ANTIC instruction did not generate a DLI on
each line if DLI was enabled. Fixed
- The rather ugly re-generation of ANTIC modelines for character-based
modes was removed. This simplified the design, but might impact the
emulation quality in some corner cases. A new ANTIC design would be
required to fix this. More careful timing in display build-up should
make this unnecessary anyhow.
- DMA border computation is now much more canonical and cleaned up.
- Since a lot of the internal timing should now work "on the cycle",
there is no longer a need to configure some of the ANTIC variables, thus
parts of the ANTIC preferences have been removed.
- CPU emulation includes now parts of the unstable opcode family xB
(opcodes whose lower nibble is B).
- The CPU emulation includes now the emulation of most (if not all) 6502
bugs: Forgetting conflicting NMIs, IRQs and BRKs (!).
Wait-cycle allocation was partially wrong and created conflicts between
memory-refresh cycle allocation and WSYNC requests. This was fixed.
- As a side effect, the special "double WSYNC" check was no longer
necessary and was removed. The emulation is correct anyhow.
- Some CPU preferences were removed because the emulation is considered
to be precise anyhow.
- PIA DDR register reads were not emulated correctly.
- PIA emulation includes now flank-detection on CA2 and CB2 plus
interrupt generation, and thus should be complete.
- POKEY 9 and 17 bit random generators are now emulated precisely, and
the generated "random" numbers should be now identical to those on the
real hardware.
- POKEY two-tone mode should now be emulated correctly, including the
cycle timing for the linked channels.
- Some race conditions for the serial control mode should now be
emulated correctly.
- POKEY direct serial input should now work fine with the SIO emulation,
though direct serial output does not yet work.
- Handling of the POKEY keyboard generation was wrong and should now
work correctly.
- The SIO patch resets now also the audio registers and the IRQ control
of POKEY to work around some software bugs.
- Os++ did not check properly for the RESET bit in the Antic NMI
register and could have triggered false resets under some race conditions.
- The legacy return value for the write-byte bus access was removed as
it was no longer required since a long time.

See for more info.
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