[ATARI] Altirra x86 i x64 4.50 test 8 06/04/2026

Altirra x86 i x64 4.50 test 8 06/04/2026

features added:

• Cartridge: The!Cart emulation now supports mode 37 (MegaCart 4M) from newest CPLD firmware.
  
• Cassette: Tape Control dialog is now resizable and has options to load/save/unload tapes.

bugs fixes:

• Disk: Standard disk emulator now turns on motor on disk change for 1050 and Indus GT profiles to emulate density detection.
  
• VBXE: GTIA size mode 2 lockup bug is no longer emulated when VBXE is active. 

author's comment:

• Fixed a debugger crash with Happy 1050 full emulation.
• Fixed motor indicator being left on when removing a Indus GT full emulation device.
• Additional minor optimization and signed zero fixes to AltirraOS math pack and FP acceleration.
• Standard disk drive emulation now simulates motor turning on momentarily on disk change for density detection.
• Fixed VBXE incorrectly emulating P/M graphics size 2 bug, which it doesn't support.
• Tape control dialog is now resizable and has new/load/save options.
• Added support for emulating updated The!Cart firmware with MegaCart 4M support.

Altirra x86 i x64 4.50 test 7 29/03/2026

Sargon 3 (1985, Hayden Software)

features added:

• Command Line: Added /cmd and /cmd1 switches for invoking UI commands from the command line.

bugs fixes:

• Disk: Adjusted XF551 style high speed timing on generic emulation profile and split XF551/USD high speed timings.
• Recorder: SAP recorder now uses prescribed text for unknown author/title

author's comment:

• Split and readjusted XF551 and USDoubler style high speed timings in standard disk emulator.
• Fixed Indus GT ROM version autodetection names to match the Field Service Manual.
• Added /cmd and /cmd1 switches to invoke UI commands from the command line.
• Fixed broken <<= and >>= operators in custom device compiler.
• SAP type R recorder now uses <?> for unknown fields.
• Fixed misspelling of IFP as IPF in built-in debugging symbols.
• AltirraOS updated to 3.47 with math pack updates: fixed normalize routine using too many mantissa bytes, fixed underflow issue in FDIV, optimized IFP/FMUL/FDIV operations.
• Fixed log spam in the debugger with drag and drop.

Altirra x86 i x64 4.50 test 6 03/03/2026

features added:

• Devices: Added Karin Maxi Drive

bugs fixes:

• AltirraOS: Fixed screen corruption in screen editor when moving cursor with a Get Byte call. (3.46)
• Devices: Standard device emulators now support SIO timeouts where implemented by the original devices.
• Devices: Fixed erroneous control signal inputs on 850 full emulation serial port 1.
• Disk Explorer: Fixed MAC/65 decoder mis-decoding some constants.

author's comment:

• Fixed bug in MAC/65 decoding in Disk Explorer.
• Added SIO timeout for standard 1025 and 1050 emulators.
• Fixed incorrect serial port 1 control signal inputs on 850 full emulator.
• Added Karin Maxi Drive emulation.
• AltirraOS 3.46: fixed incompatible cursor behavior when reading from screen.

Altirra x86 i x64 4.50 test 5 16/02/2026

features added:

• AltirraOS: Math pack rewritten to better match standard math pack results and for TurboBasic XL compatibility.
  
• GTIA: Added emulation of known defective GTIA types.
• HLE: Fast math acceleration now much better matches standard math pack results.

bugs fixes:

• Cartridge: Added DCart to cartridge type autodetection list.
• UI: Reset Window Layout wasn't resetting undocked panes.
• UI: Layout restore is more robust at fixing panes that are off-screen or unreasonably small. 

author's comment:

• Fixed Reset Window Layout not resetting undocked panes.
• Improved recovery of off-screen panes when restoring window layout.
• Added DCart to cartridge autodetect list.
• Fixed a bug where a caption bar would sometimes draw over the performance analyzer.
• Fast math acceleration now much more closely matches the results of the standard math pack.
• Rewrote AltirraOS math pack for better compatibility with the standard math pack and compatibility with Turbo Basic XL.

I finally decided to bite the bullet and get Turbo Basic XL working on AltirraOS. The issue is that TBXL duplicates the exp/log routines in the math pack while reusing its constants, so the algorithm in the math pack has to match. Previously, the AltirraOS math pack used different algorithms, so TBXL was using the wrong polynomial constants for its algorithm and produced garbage results from several functions. A few main changes were needed to fix this:

• The polynomial approximations have been replaced with the algorithms from the upstream source that was used to write the original math pack, a book called BASIC Scientific Routines. The formulas and coefficients are largely implemented straight out of this book, with some minor changes (and errors).
• Several constants had to be moved to addresses expected by TBXL.
• Rounding has been removed from the math pack, which now truncates intermediate results like the original math pack.

Altirra x86 i x64 4.50 test 4 02/02/2026

features added:

• Custom Devices: Added continue statement.
• Custom Devices: Added C-style hex constants (0x prefix).
• Custom Devices: Added $sio.set_external_clock().

bugs fixes:

• UI: Removed inner edge on display window when there are no other docked panes visible.
• UI: Files can now be dragged from folders mapped with the H: device to paste in the emulated path to the file. 

author's comment:

• Removed the inner 3D edge on the display pane in the center well.
• Drag and drop now has the option to paste in the encoded CIO filename for a file mapped through the H: device (useful for encoded long filenames).
• Partial workaround for major drag and drop bugs in Wine (unfortunately, Wine will still hang if an error occurs).
• Custom Devices: Added continue statement and 0x-style hex literals.
• Custom Devices: Added $sio.set_external_clock().

Altirra x86 i x64 4.50 test 3 18/01/2026

Scramble (Konami, 1984)

changes:

• nw

features added:

• Cartridge: The CAR header checksum is now ignored if it is zero.

bugs fixes:

• nw

author's comment:

• Fixes shutdown crash.
• The CAR file format checksum is now ignored if the checksum is set to 0.
• Removed obsolete old checksum algorithm from compatibility system (should not affect anything, SHA256 has been in place forever)