The Apple IIgs core is now officially released on the the MiSTer FPGA platform. While I have maintained an original IIgs hardware setup for many years, the development of this cycle-accurate FPGA core offers a way for the masses to access this sometimes underappreciated Apple II computer’s software library. Since its initial beta phases a few months ago, the core has seen significant functional improvements and is now integrated into the standard update scripts for MiSTer users.
Check it out in my latest video!
Getting the system operational is straightforward. Running the “update all” script installs the core and the necessary ROM automatically. For software, I have been using disk and hard drive images sourced from community archives, specifically those curated by Alex Lee on his website “What is the Apple IIgs?”
Using a System 6.04 hard drive image provides a bootable desktop environment that mirrors the original user interface. The core currently supports mounting two hard drive or floppy images simultaneously along with an additional 3.5-inch and a 5.25-inch volume. One technical detail to note is that while the core can boot from zipped files, these images remain read-only. To save data or configurations, the files must be unzipped on the MiSTer storage.
The user interface of the IIgs was notable for being the first color Apple GUI environment, predating the color Macintosh. In testing various titles like Tunnels of Armageddon and Task Force, the performance remains consistent with the original 2.8 MHz hardware. For those who find the native speed restrictive, the core includes options to emulate period-accurate accelerators like the Zip GS or TransWarp GS. The audio quality, which was somewhat muffled in earlier versions of the core, is now clear and reflects the capabilities of the original Ensoniq sound chip.
Beyond gaming, I tested the core’s compatibility with demo scene software that often pushed the hardware to its max. The Free Tools Association (FTA) produced several technically demanding demos, such as Space Harrier and Modulae. Most of these run without issue, though minor graphical glitches occasionally appear in specific demos like FTA’s Xmas.
For users interested in visual accuracy, the core supports RGB output through the MiSTer analog board, which allows for connection to CRT monitors and televisions. It looked spectacular on my JVC TV that has an RGB component input.
One of the more interesting features available is the MiSTer platform’s ability to provide modem emulation through a Telnet connection. By adjusting the UART settings in the MiSTer menu, the IIgs core can communicate over a network as if it were using a physical serial port. Using terminal software like Spectrum, I was able to dial into Telnet-based bulletin board systems. The core supports two-way communication, meaning it is also possible to host a BBS directly from the device. The Telnet feature simulates a modem ring and can answer standard Hayes AT commands to answer the virtual phone.
The system also maintains backwards compatibility with the broader Apple II library. When running older software designed for the Apple II Plus or IIe, such as Oregon Trail, the system speed must be adjusted manually in the control panel to 1 MHz to ensure the software does not run too quickly.
With 8 MB of onboard RAM—more than many original machines possessed—this new core functions as a comprehensive recreation of the hardware in its most “souped up” state. The efforts of the contributing developers have resulted in a stable environment for exploring this specific era of computing history.













