z486_MiSTer is an experimental PC core for MiSTer built around the z486 CPU, an 80486-class pipelined FPGA CPU written in SystemVerilog. The processor combines a fast frontend and hardwired implementations of common instructions with microcoded control for complex x86 operations. It also includes experimental, incomplete x87 support sufficient to run TurboQuake.
The core delivers roughly 486DX2-66-class performance. It runs the Doom timedemo at 29.1 FPS at maximum detail, compared with 21.0 FPS on ao486 using the same MiSTer setup.
The core uses MiSTer SDRAM for system memory and supports 16, 32, 64, or 128 MB configurations. Video hardware provides VGA and ET4000-compatible SVGA modes.
z486_MiSTer requires an SDRAM module. The SDRAM XS-D v2.5 module has been
verified to work. It also requires MiSTer main MiSTer_20260823 or newer;
run Scripts → update before installing the core.
Download the latest build from the releases page, then place the files as follows:
z486_*.rbfin/media/fat/_Computer- boot0.rom, boot1.rom, and disk
images (
.vhd) in/media/fat/games/Z486
Development and compatibility discussion is available in the MiSTer FPGA forum thread.
MISTERFS shares /media/fat/games/Z486/shared with DOS using the current ao486 driver. If using EMM386, reserve CE00-CFFF before loading the driver.
The OSD offers Full, 56, 30, 15, 6, 5, 4 and 3 MHz-equivalent execution rates. Existing four-speed SYSCTL commands remain compatible; use the OSD for the four new rates. The SYSCTL interface documents core/version detection for future utility updates.