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C-One . FPGA-64 . Turbo Chameleon

FPGA-64

A realtime Commodore 64 emulator in a FPGA.

• 6502/6510 compatible CPU (including the original instruction timing, bugs and 'reserved' opcodes)
• VIC-II video chip emulation with scandoubler (or scan-converter) for VGA display.
• PS/2 keyboard interface connected to an emulated 8x8 keyboard matrix. Numeric keys emulate joystick movement.
• CIA replacement (incomplete) providing timers, I/O and diskdrive interface
• PLA-chip and bus multiplexing emulation for bankswitching and cartridge support

FPGA-64 License

Download FPGA-64

Current version (C-One binary, no source):

Because this version contains code from the Chameleon project, I can't release the VHDL sources. So this version is for C-One owners only.

/zips/fpga64_029.zip (20090623)

/zips/fpga64_028newboot.zip (20090309)

/zips/fpga64_028bin.zip (20081026)

older versions:

zip contains vhdl source code, project files, documentation and binaries for the C-One Reconfigurable computer. Although the core is configured to run on a C-One board, it is not too difficult to port it to another FPGA.

/zips/fpga64_027.zip (20081009)

/zips/fpga64_026.zip (20080724)

/zips/fpga64_025.zip (20080203)

/zips/fpga64_024.zip (20080131)

/zips/fpga64_023.zip (20080128)

/zips/fpga64_022.zip (20080121)

/zips/fpga64_021.zip (20070709)

/zips/fpga64_020.zip (20070512)

/zips/fpga64_019.zip (20070508)

/zips/fpga64_018.zip (20070317)

/zips/fpga64_cone_017.zip (20061001)

/zips/fpga64_cone_016.zip (20060925)

/zips/fpga64_cone_alpha15.zip (20060920)

/zips/fpga64_cone_alpha14.zip (20060913)

/zips/fpga64_cone_alpha13.zip (20060908)

/zips/fpga64_cone_alpha12.zip (20060904)

Known open Issues/Bugs

Using DMA input on cartridge port crashes machine.

'ICR01' from testsuite goed wrong.... same behaviour is in VICE.
There are some problems with One-Shot mode in the CIA timers. Shouldn't influence too much software.

TOD clock (Timer of day) and alarm is not working correctly in CIAs.

KCS cartridge unsupported (garbage video)
MMC-Replay unsupported (it works 'sometimes')

History

Version: 0.29bin
- Swapped joystick ports and pot-X/Y registers. 1351 mouse (and clones) can now be used on the C-One.
- Some VIC-II emulation fixes for the sprites.


Version: 0.28bin
- Fixed IRQ/NMI pins on cartridge port. Signals are now bidirectional.
- Second SID is now mapped at $D420-$D43F allowing playback of stereo music.
- Left/Up cursor keys force right-shift down (this used to be the left-shift). This solves MMC-64 keyboard issues.
- Uses VIC-II emulation from the Chameleon dev-tree. Results in better graphics compatibility.


Version: 0.27
- Fixed 'picture is shifted to the left' bug in the scan-converter.
- Fixed bug in buslogic preventing use of MMC-Replay.


Version: 0.26
- Reading from SID chip now implemented. (emulated registers removed)
- Fixed decimal mode of ARR instruction
- CPU speed changes together when the video mode is changed by pressing F12.
- Fixed speed of dotclock and phi. System now runs at 0.9850Mhz for PAL
  and 1.026Mhz for NTSC. Most floppy turbo loaders can now operate.
- VGA frame refresh rate now correct at 50Hz and 60Hz.
- Catridge port stability improved by adding data register that buffers on read.


Version: 0.25
- Shifted pixelclock phase for C-One cartridge port so it looks more like a real C64.
  (cpu clock changes when pixel-clock level is high)
- Added IRQ and NMI input from C-One cartridge port.


version: 0.24
- Fixed bug in sprite logic introduced during VIC-II rewrite. MCurrentPixel didn't get reset.
- Mapped BA to FPGA pin 149 (PCI pad1). It enables better cartridge emulation (requires a PCB patch).
- Increased length of the 'write' signal so a RetroReplay cartridge can freeze the machine.


Version: 0.23
- Partial support for the cartridge port on the C-One.
- Fixed bug in keyboard matrix, it had problems recognising the first key-press after boot.
- Merged Mark McDougall's keyboard extensions. Numeric keypad on ps/2 keyboard can be used as a joystick.
  Use the 0 key as fire button. F11 switches between emulation of joystick A or joystick B.


Version: 0.22
- Increased number of reset cycles to 4095 in example toplevel. Prevents problems during startup on other FPGA boards.
- Lots of small fixes to the CPU. There is only one opcode bug remaining (ARR in decimal mode).
- Rewritten large parts of the VIC-II code. Now it properly supports delayed-dma tricks.
- Sprite-stretching by toggling Y-expansion bit is now supported.
- 9th sprite is displayed on correct position in the Krestage 3 demo.
- Timing between $D020 and screen pixels is cycle correct.


Version: 0.21
- Implemented "ANE" undocumented opcode.
- Implemented "SHA" undocumented opcode.
- Implemented "SHX" undocumented opcode.
- Implemented "SHY" undocumented opcode.
- Implemented "LAS" undocumented opcode.
- Fixed CPU behaviour when NMI interrupts pending IRQ or BRK.
- Fixed Clear CIA IRQ, so will not block TimerA/B IRQ occuring in exact same cycle.
- Fixed CIA behaviour during toggle oneshot bit.


Version: 0.20
- Fixed IRQ and NMI timing of 6510 cpu.
- Fixed 8 bit vs 9 bit compare for sprite Y position. This fixes missing sprites in the game 'Delta'.


version: 0.19
- Implemented "LXA imm" undocumented opcode.
- Implemented CIA timers underflow toggle for I/O-pin PB6 and PB7.
- Fixed CIA chain mode (timerA controls timerB).
- Fixed reload behaviour during CIA timer underflow.
Cosmetic:
- Renamed interrupt flags in CIA.
- VIC registers are directly connected to cpu. They are not routed through buslogic anymore.
- Replaced 'mob' structure in VIC source with separate signals as some vhdl compilers don't like it.


Version: 0.18
- Added other FPGA platform files.
- Changed reset moment of an internal sprite flag. Now sprites can be displayed in right side border.
- CIA has flag_n input (cassette, rs232 and SRQ line).


Version: 0.17
- Implemented "SBX imm" (aka AXS imm) undocumented opcode.
- Optimised CIA Timer to save around 100 logic-elements in FPGA.


Version: 0.16
- Fixed cpu IO registers at $0000/$0001 and moved them from buslogic to separate vhdl file.
- Fixed a CIA TOD bug preventing starting of TOD in some cases.
- Fixed IRQ/NMI timing of the branch instructions. Interrupts are delayed one cycle if branch is taken, but there is no page crossing.
- Created build and release scripts, so it is easier and less error prone to make release versions.


version: Alpha15
- Fixed F7 key (was wrongly mapped to F4)
- Implemented 'pulseRd' signal so CIA/VIC-II special readonly registers are only triggered on read not write.
- Did a lot of CIA timer fixes. The crX_inmode flags work correctly now. (So timerB can be slaved to timerA)
- Added one cycle delay while writing to the VIC-II registers. The side-border can be opened now!
- Added one cycle delay to NMI.
- Fixed the cycle count of indexed read-modify-write opcodes.


Version: Alpha14
- Splitted 65xx ALU in two for implementation of undoc-opcodes.
- Implemented undoc-opcodes: SLO(ASO) RLA SRE RRA SAX DCP ISC ANC


Version: Alpha13
- Fixed readback of VIC-II sprite expansion registers (fixes random sprite corruption in Paradroid).
- Fixed reading of memory location 3FFF/39FF in VIC-II idle mode.
- Eliminated extra character that appeared on the left side after poke53270,15
- Fixed 2 pixel offset of sprite when it was expanded in X direction. (allows 'Impossible Mission' to be played)
- Changed IRQ timing in cpu (necessary for certain VIC-II tricks to work).


Version: Alpha12
- Increased blanking area to remove artifacts in the first lines of the screen.
- Changed I flag behaviour for 'RTI'. No interrupts are possible just after a RTI.
- Fixed VIC-II emulation so number of cycles/line is 63.
- Fixed bug in generation of (virtual) BA signal.
- Moved cycle of the sprite calculations to enable sprite multiplexing.


Version: Alpha11
- Fixed 8 pixel left shift of bitmap graphics. Lots of games had distored graphics
- Optimised some of the bus-logic, somewhat easier for the vhdl compiler.


Version: Alpha10
- Fixed video sync issue introduced in Alpha9
- Because reading from real SID isn't yet possible, a dummy register $1B is created for games that need it.
- Partial implementation of CIA TOD (time of day)


Version: Alpha9
- Enabled NMI interrupt (did fix in alpha8 but forgot to enable it)
- Fixed crash when "BRK" was encountered after a branch across page boundary.
- Implemented various undocumented "NOP" opcodes.


Version: Alpha8
- Implemented Sprite priority
- Optimised VIC-II graphic modes for less FPGA resources use.
- Fixed NMI interrupts
- Fixed "CMP abs,y" instruction
- Fixed "ORA (zp,x)" instruction
- Fixed "BIT xxx" instructions
- Fixed crash when TXS instruction was executed while interrupt pending.
- Fixed zp,x so it wraps around staying in page 0.
- Fixed "STX zp,x"


Version: Alpha7
- Note: Alpha7 has introduced alot of CPU bugs as it contained a complete new 6510 core
        All of these problems are rectified in Alpha8 and later.

- Implemented Sprite X expansion.
- Implemented Sprite Y expansion.
- Added support for multi-color sprites.
- Added sprite-background collision detection.
- New 6510 emulation for less FPGA resources use.


version: Alpha6

Added sprite-sprite collision detection + interrupt.
VIC-II emulation should be cycle exact now.


Version: Alpha5

After a long delay and some very usefull help from Tobias.
There is another alpha release of the "PAL" core for your c-one.

- Contains preliminary sprite support in VIC-II
- Improved flicker-fixer (hopefully all monitors support the 50Hz mode now...)
- FPGA64 specific MMU/bootload disabled in this version, it uses
  currently the same rom/memory layout as Jerry's ntsc core.

Use F12 to switch between PAL (50Hz) or NTSC (60Hz) mode.

First visible result

Although the startup-screen was recognisable, it was not correct. After debugging I discovered the instructions 'TAX' and 'INC abs', didn't produce the correct result. The 'TAX' error is responsable for the left/down shifted line. The incorrect 'INC abs' distorted the number of free bytes calculation.

Newer versions emulate more VIC tricks

Here FPGA-64 is running the "Krestage 2" demo, showing that delay-DMA effects are emulated correctly. (notice there is some debugging info at the top and left of the screen. This logic is not included in release versions.)