[VCS] Gopher2600 0.41.0 04/06/2025

Atari 2600 Emulator: Gopher v0.41.0 04/06/2025

Screenshot Improvements

• RF noise disabled during screenshots
• Overlay (FPS information, notifications, etc.) not included in screenshot

Improved DWARF decoding

• Correct handling of relocatable ELF files
• Mutliple executable ELF sections now supported

Corrections to ARM FPU (Plus/Unocart emulation)

• Most significantly the setting of RoundZero as the default rounding type

Addtional ELF implementations

• VcsWrite6()
• R_ARM_THM_JUMP24 relocation type

Bug fixes

• POKE command now affects TIA/RIOT registers correctly
• TIA Audio volume sampling could result in mixing overflow and a crash, during rewinding

Other

• Shift key can be used to extend selection in Source and Tracker windows

Atari 2600 Emulator: Gopher v0.40 01/05/2025

Colour Model

• phase adjustments can now be applied to the standard Stella palette
• this more closely matches modern expectation while also providing the flexibility to adjust the phase if required
• removed 'Legacy Colour Model' option
  • preview releases of v0.40.0 allowed A/B testing of the 'legacy model' and a purely mathematical model
  • explanation of the current model in the blog https://jetsetilly.github.io/Gopher2600-Blog/posts/improving-the-ntsc-colour-model/

Improved DWARF decoding

• binaries compiled with no optimisation (or -O0) now show variable information in the debugger
  • absence of .debug_loc was incorrectly considered to mean no location information was available
• framebase uses the yield address and not the current PC address
  • very often this doesn't matter but incorrect use of the ARM pipeline caused variables to be missing unexpectedly
• function building uses specification attribute if appropriate
  • this attribute seems to be used in object-oriented style C++ programs, and is probably a feature of other OO languages

ELF

• added vcsJmpToRam3(), vcsPokeRomByte() and vcsSetNextAddress() strongarm functions
• improved performance when accessing executable memory
• ELF can now annotate coprocessor disassemblies

Bug Fixes

• race error between SDL audio and playscreen overlay (the FPS overlay)

Atari 2600 Emulator: Gopher v0.35.3 14/12/2024

Television

• Corrected how Brightness / Contrast controls work
• Improved VSYNC
  • TV tolerant of brief desynchronisations

Debugger

• Stepping back works correctly in conjunction with recent user input
  • Due to how the rewind system worked, any user input since the start of the last frame and the current position of the emulation would be lost on step back. This is now not the case

PlusROM

• PlusROM host/path information was read incorrectly
  • Caused problems with segmented banking schemes, like 3e+ [issue #35]

Television Brightness and Contrast controls work a bit differently as of the release. You may need to readjust those settings (press F10 button for preferences window)

Atari 2600 Emulator: Gopher v0.35.2 23/11/2024

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Changes since v0.35.1

• Added cartridge mapper

• FA2
  • eg. Star Castle
  • non-volatile RAM for this cartridge type stored in the nv_ram of the configuration direcotry
• BF
  • eg. The Realm of Riesig

• Supercharger

• Running a Supercharger game loaded from an audio file resulted in performance drop, even when the tape had stopped loading
• Performance is now equal as when loading from a fastload binary file

• Disassembly

• Disassembly is now completed in the background, leading to quicker loadtimes, particularly for very large cartridges

• Television / CRT Effects

• Blur shader is now applied more evenly
  • this is most noticeable with high bloom values but produces better results generally
• Disabling the ghosting effect would cause the image to flip
• More efficient clearing of GL frame buffers
  • small but significant performance improvement

• Regression testing

• Playback scripts can now be re-recorded automatically
  • REDUX command now works with all regression test types

Atari 2600 Emulator: Gopher v0.35.1 7/10/2024

Bug Fixes

• Some PlusROMs were not detected properly
• Only the first 1024 bytes were searched for the fingerprint, which is insufficient for some ROMs
• There is (always has been) a verification step to make sure the URL at the NMI location is correct so false positives should not be a problem

Atari 2600 Emulator: Gopher v0.35.0 2/10/2024

Bug Fixes

• Rewinding of ELF binaries caused visual artefacts on screen
• Changes to screen rendering prevented the VideoChess bot from starting
  • Bug introduced in v0.31.0
• Added ELF to list of valid ROM extensions
  • A file with the .elf extension would not be shown by the ROM selector
• Mouse wheel events could crash the emulator
  • This affected MacOS builds on machines where mouse-wheel style scrolling is done with a touch-pad
• Replay button in tracker window could crash the emulator

Changes

• TIA audio sampled every colour clock
  • This fixes problems with ROMs where the channel volume is update more than twice per scanline
• Added option to enable warning for "undefined symbols" when loading ELF ROMs
  • It is possible to compile an ELF binary with undefined symbols. Rather than reject the file when it is loaded, I have chosen to allow the ROM to execute and to continue until the symbol is referenced (which may never happen)
  • The addition of the warning is in addition to this behaviour and gives the developer the option of being notified of symbol errors sooner
• Added CARTRIDGE SETBANK command
  • It wasn't possible previously to set the current bank of a cartridge. I had originally chosen to avoid the problem because of the high variety of ways a mapper might implement banking (if at all)
  • The options to the SETBANK command vary depending on the specific mapper but generally, a mapper will expect a numeric value

    • Segmented mappers can take multiple numeric values. Separate values with a colon

    • In some instances, segments can be mapped to cartridge RAM. add an 'R' after the segment number to indicate the use of RAM. For example, the 3e mapper allows very flexible mapping of RAM

      CARTRIDGE SETBANK 1R:2

    • Some segmented mappers only allow a predefined 'pattern' of segments. In these cases the numeric value to the SETBANK command will be a pattern number. The two mappers affected by this are Supercharger and Wickstead Design

Other Changes

• Added ELF support for REL32 and PREL31 relocation
• Improved DWARF support for typedefs
• Better decision making over whether variables are in global scope
• Prevent possibility of infinite recursion in DWARF builder

Atari 2600 Emulator: Gopher v0.34.0 19/07/2024

• Changes / Bug Fixes

• Specifying a mapper will not add superchip unless asked
• ARM would sometimes loop endlessly on startup
  • caused by ROMs causing execution errors and not being caught
• DPC+ and CDJF always emulate the end-of-custom-program JMP even when immediat mode is enabled
• 6507 more careful with system symbols
  • system symbols no longer appear as operands for immediate instructions
• ARM yields address of most recent instruction rather than the current PC
  • this isn't a problem for 16bit instructions
    - but for 32bit instructions it resulted in confusing feedback in the source window
• Better handling of DWARF data from alternative ELF files

Atari 2600 Emulator: Gopher v0.33.0 6/07/2024

• improvements

• ELF uses less memory
  • High memory usage is a direct consequence of the rewind system
  • ELF memory is only recorded if it the memory block is volatile
  • Recorded memory is compressed (using a very simple RLE algorithm)
• ARMv7_M architecture
  • Marginal performance improvement in cycle counting
• Television can now cause emulation to break into debugger
  • eg. if VSYNC is absent or too short, etc.
  • Toggled via preferences window (television tab)
• FPS overlay in playmode shows VBLANK/VSYNC information
  • Timeline window in debugger shows VSYNC trace
• Debugger shows break condition in toolbar
  • Information shown is currently very rough
• Holding down the STEP buttons in the control window is now faster

• changes / bug fixes

• DPC+ more careful about resetting fraction fetcher counter when setting the fraction fetcher low byte
  • Whether the reset happens depends on the version of the driver being emulated
• Supercharger
  • Rewind fix in 0.32.0 for fastload implementation was incomplete
• Coprocessor Source Window
  • Fixed parsing of comment lines

• Emulator Development

• Fixed profile targets in Makefile
  • Changes made in b48d487 limited the functionality of pprof

Atari 2600 Emulator: Gopher v0.29.1

Atari 2600 Emulator: Gopher v0.29.0

Atari 2600 Emulator: Gopher v0.28.0

Gravitar (Atari, 1983)

Atari 2600 Emulator: Gopher v0.27

Atari 2600 Emulator: Gopher v0.26.2b

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Atari 2600 Emulator: Gopher v0.26.2 Latest

 MovieCart

• Timecode rendered correctly when movie is rewound to beginning/ This also removes visual artefacts visible at the bottom of the movie image
• Controls now match the reference implementation

Atari 2600 Emulator: Gopher v0.26.1

Atari 2600 Emulator: Gopher v0.26.0

Changes from v0.25.0

 MovieCart

•  Added support for new MovieCart format

 TV

•  SECAM support
•  TV rotation. Manual and automatic
•  Only Moviecart makes use of automatic rotation currently

 ELF

•  StrongARM ROMs use the correct color table for the current television

 ARM debugging

•  Corrected DWARF CALLERS
•  ARM disassembly shows function in tooltip

 Other

•  SDL version logged on startup
•  VideoChess bot can now work with levels 2-8 as well as level 1

Atari 2600 Emulator: Gopher v0.26.1

Atari 2600 Emulator: Gopher v0.26.0

Changes from v0.25.0

 MovieCart

•  Added support for new MovieCart format

 TV

•  SECAM support
•  TV rotation. Manual and automatic
•  Only Moviecart makes use of automatic rotation currently

 ELF

•  StrongARM ROMs use the correct color table for the current television

 ARM debugging

•  Corrected DWARF CALLERS
•  ARM disassembly shows function in tooltip

 Other

•  SDL version logged on startup
•  VideoChess bot can now work with levels 2-8 as well as level 1