GUI CPU
Configures the emulated Motorola 680x0 processor, floating-point unit, memory management unit, JIT compiler, and CPU speed settings.
Selects the 680x0 processor to emulate:
- 68000 — Original Amiga 500/1000/2000 CPU
- 68010 — Slightly faster variant of the 68000, used in some accelerators
- 68020 — 32-bit CPU used in the Amiga 1200
- 68030 — Amiga 3000/4000 CPU; includes an MMU
- 68040 — Faster 32-bit CPU with integrated FPU and MMU
- 68060 — Fastest Amiga CPU
- Restricts the address bus to 24 bits, matching the original A500/A1200 hardware
- Required for compatibility with software that relies on the 24-bit address space
- Disable when using Zorro III (Z3) RAM expansions
- Approximates the prefetch pipeline of the 68000/010
- Required for timing-sensitive games and demos
- Automatically enabled when cycle-exact emulation is active
- Emulates unimplemented 68060 instructions in software
- Only available when the 68060 CPU model is selected without JIT
- Emulates the CPU data cache present in 68030 and later processors
- Required for some 68030+ software; only available when JIT is disabled
- Enables Just-In-Time compilation of 68k code to native host code
- Greatly speeds up CPU emulation but reduces compatibility
- Requires a 68020 or higher CPU model with 32-bit addressing
- Disables Memory Management Unit emulation
- Enables full MMU emulation
- Required for operating systems that use virtual memory (e.g., NetBSD, Linux/m68k)
- Enables the EC (Economy) variant of the MMU, which has a reduced address bus
- Disables the Floating Point Unit
- External Motorola 68881 FPU; used with 68020 or 68030 CPUs
- External Motorola 68882 FPU; faster version of the 68881
- Uses the FPU built into the 68040 or 68060 CPU
- Enables more accurate but slower FPU emulation
- Host (64-bit) — Uses the host CPU's 64-bit double precision
- Host (80-bit) — Uses the host CPU's 80-bit extended precision (x87)
- Softfloat (80-bit) — Software-emulated 80-bit precision; most accurate but slowest
- Emulates unimplemented FPU instructions in software
- Only available when an FPU is selected and JIT is disabled
- Runs the CPU as fast as the host system allows
- Best for Workbench use and applications; not suitable for most games
- Matches the original Amiga CPU speed
- Required for most games and demos
- Fine-tunes the CPU speed as a percentage offset from the base speed
- Range: -90% to +5000%; available when "Fastest Possible" is not selected
- Controls how aggressively the emulator yields CPU time when the emulated CPU is idle
- Higher values reduce host CPU usage at the cost of emulation responsiveness
- Sets the clock multiplier for cycle-exact or compatible emulation
- Options: 1x, 2x (A500), 4x (A1200), 8x, 16x
- A read-only field next to the combo shows the resulting frequency in MHz
- Runs CPU emulation on a separate thread
- Experimental; not available with compatible or cycle-exact modes
- Enables PowerPC CPU emulation for CyberStorm PPC or Blizzard PPC accelerator boards
- Requires a 68040 or higher CPU model
- Controls how much host CPU time is used when the M68K is stopped waiting for the PPC
- Range: 0–10; only active when PPC emulation is enabled
- Adjusts the speed of the emulated x86 bridgeboard CPU as a percentage
- Only active when an x86 bridgeboard is configured
- Sets the size of the JIT translation cache
- Range: 0 (disabled) to 5 steps (1 MB, 2 MB, 4 MB, 8 MB, 16 MB)
- The current size in MB is shown next to the slider
- Enables JIT compilation for FPU instructions
- Enables a JIT optimization for constant branch targets
- Flushes the entire JIT cache on every reset or resize
- Skips updating CPU status flags in compiled code; faster but less compatible
- Catches memory access faults in JIT-compiled code
- Direct — JIT accesses emulated memory directly; faster but less compatible
- Indirect — JIT uses indirect memory access; slower but more compatible